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//
//      COPYRIGHT 2000 by Bruce L. Jacob
//      (contact info: http://www.ece.umd.edu/~blj/)
//
//      You are welcome to use, modify, copy, and/or redistribute this implementation, provided:
//        1. you share with the author (Bruce Jacob) any changes you make;
//        2. you properly credit the author (Bruce Jacob) if used within a larger work; and
//        3. you do not modify, delete, or in any way obscure the implementation's copyright 
//           notice or following comments (i.e. the first 3-4 dozen lines of this file).
//
//      RiSC-16
//
//      This is an out-of-order implementation of the RiSC-16, a teaching instruction-set used by
//      the author at the University of Maryland, and which is a blatant (but sanctioned) rip-off
//      of the Little Computer (LC-896) developed by Peter Chen at the University of Michigan.
//      The primary differences include the following:
//        1. a move from 17-bit to 16-bit instructions; and
//        2. the replacement of the NOP and HALT opcodes by ADDI and LUI ... HALT and NOP are
//           now simply special instances of other instructions: NOP is a do-nothing ADD, and
//           HALT is a subset of JALR.
//
//      RiSC stands for Ridiculously Simple Computer, which makes sense in the context in which
//      the instruction-set is normally used -- to teach simple organization and architecture to
//      undergraduates who do not yet know how computers work.  This implementation was targetted
//      towards more advanced undergraduates doing design & implementation and was intended to 
//      demonstrate some high-performance concepts on a small scale -- an 8-entry reorder buffer,
//      eight opcodes, two ALUs, two-way issue, two-way commit, etc.  However, the out-of-order 
//      core is much more complex than I anticipated, and I hope that its complexity does not 
//      obscure its underlying structure.  We'll see how well it flies in class ...
//
//      CAVEAT FREELOADER: This Verilog implementation was developed and debugged in a (somewhat
//      frantic) 2-week period before the start of the Fall 2000 semester.  Not surprisingly, it
//      still contains many bugs and some horrible, horrible logic.  The logic is also written so
//      as to be debuggable and/or explain its function, rather than to be efficient -- e.g. in
//      several places, signals are over-constrained so that they are easy to read in the debug
//      output ... also, you will see statements like
//
//          if (xyz[`INSTRUCTION_OP] == `BEQ || xyz[`INSTRUCTION_OP] == `SW)
//
//      instead of and/nand combinations of bits ... sorry; can't be helped.  Use at your own risk.
//
//      DOCUMENTATION: Documents describing the RiSC-16 in all its forms (sequential, pipelined,
//      as well as out-of-order) can be found on the author's website at the following URL:
//
//          http://www.ece.umd.edu/~blj/RiSC/
//
//      If you do not find what you are looking for, please feel free to email me with suggestions
//      for more/different/modified documents.  Same goes for bug fixes.
//
//
//      KNOWN PROBLEMS (i.e., bugs I haven't got around to fixing yet)
//
//      - If the target of a backwards branch is a backwards branch, the fetchbuf steering logic
//        will get confused.  This can be fixed by having a separate did_branchback status register
//        for each of the fetch buffers.
//
// ============================================================================
//        __
//   \\__/ o\    (C) 2013-2016  Robert Finch, Stratford
//    \  __ /    All rights reserved.
//     \/_//     robfinch<remove>@finitron.ca
//       ||
//
// This source file is free software: you can redistribute it and/or modify 
// it under the terms of the GNU Lesser General Public License as published 
// by the Free Software Foundation, either version 3 of the License, or     
// (at your option) any later version.                                      
//                                                                          
// This source file is distributed in the hope that it will be useful,      
// but WITHOUT ANY WARRANTY; without even the implied warranty of           
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the            
// GNU General Public License for more details.                             
//                                                                          
// You should have received a copy of the GNU General Public License        
// along with this program.  If not, see <http://www.gnu.org/licenses/>.    
//
//
// Thor Superscaler
//
// This work is starting with the RiSC-16 as noted in the copyright statement
// above. Hopefully it will be possible to run this processor in real hardware
// (FPGA) as opposed to just simulation. To the RiSC-16 are added:
//
//      64/32 bit datapath rather than 16 bit
//   64 general purpose registers
//   16 code address registers
//   16 predicate registers / predicated instruction execution
//    8 segment registers
//      A branch history table, and a (2,2) correlating branch predictor added
//      variable length instruction encodings (code density)
//      support for interrupts
//      The instruction set is changed completely with many new instructions.
//      An instruction and data cache were added.
//      A WISHBONE bus interface was added,
//
// 53,950 (86,500 LC's)
// with segmentation
// no bitfield, stack or FP ops
//
// ============================================================================
//
`include "Thor_defines.v"
 
module Thor(corenum, rst_i, clk_i, clk_o, km, nmi_i, irq_i, vec_i, bte_o, cti_o, bl_o, lock_o, resv_o, resv_i, cres_o,
    cyc_o, stb_o, ack_i, err_i, we_o, sel_o, adr_o, dat_i, dat_o);
parameter DBW = 32;         // databus width
parameter ABW = 32;         // address bus width
parameter RSTCSEG = 52'h0;
parameter RSTPC = 64'hFFFFFFFFFFFC0000;
parameter STARTUP_POWER = 16'hFFFF;
parameter IMCD = 6'h30;
localparam AMSB = ABW-1;
parameter QENTRIES = 8;
parameter ALU1BIG = 0;
parameter RESET1 = 4'd0;
parameter RESET2 = 4'd1;
parameter IDLE = 4'd2;
parameter ICACHE1 = 4'd3;
parameter DCACHE1 = 4'd4;
parameter IBUF1 = 4'd5;
parameter IBUF2 = 4'd6;
parameter IBUF3 = 4'd7;
parameter IBUF4 = 4'd8;
parameter IBUF5 = 4'd9;
parameter NREGS = 127;
parameter PF = 4'd0;
parameter PT = 4'd1;
parameter PEQ = 4'd2;
parameter PNE = 4'd3;
parameter PLE = 4'd4;
parameter PGT = 4'd5;
parameter PGE = 4'd6;
parameter PLT = 4'd7;
parameter PLEU = 4'd8;
parameter PGTU = 4'd9;
parameter PGEU = 4'd10;
parameter PLTU = 4'd11;
input [63:0] corenum;
input rst_i;
input clk_i;
output clk_o;
output km;
input nmi_i;
input irq_i;
input [7:0] vec_i;
output reg [1:0] bte_o;
output reg [2:0] cti_o;
output reg [4:0] bl_o;
output reg lock_o;
output reg resv_o;
input resv_i;
output reg cres_o;
output reg cyc_o;
output reg stb_o;
input ack_i;
input err_i;
output reg we_o;
output reg [DBW/8-1:0] sel_o;
output reg [ABW-1:0] adr_o;
input [DBW-1:0] dat_i;
output reg [DBW-1:0] dat_o;
 
integer n,i;
reg [1:0] mode;
reg [DBW/8-1:0] rsel;
reg [3:0] cstate;
reg [ABW:0] pc;                               // program counter (virtual)
wire [ABW-1:0] ppc;                              // physical pc address
reg [ABW-1:0] interrupt_pc;     // working register for interrupt pc
reg [DBW-1:0] vadr;                              // data virtual address
reg [3:0] panic;         // indexes the message structure
reg [128:0] message [0:15];       // indexed by panic
reg [DBW-1:0] cregs [0:15];               // code address registers
reg [ 3:0] pregs [0:15];          // predicate registers
`ifdef SEGMENTATION
reg [DBW-1:12] sregs [0:7];      // segment registers
reg [DBW-1:12] sregs_lmt [0:7];
`endif
reg [2:0] rrmapno;                               // register rename map number
wire ITLBMiss;
wire DTLBMiss;
wire uncached;
wire [DBW-1:0] cdat;
reg pwe;
wire [DBW-1:0] pea;
reg [DBW-1:0] tick;
reg [DBW-1:0] lc;                                // loop counter
reg [DBW-1:0] rfoa0,rfoa1;
reg [DBW-1:0] rfob0,rfob1;
reg [DBW-1:0] rfoc0,rfoc1;
reg [DBW-1:0] rfot0,rfot1;
reg ic_invalidate,dc_invalidate;
reg ic_invalidate_line,dc_invalidate_line;
reg [ABW-1:0] ic_lineno,dc_lineno;
reg ierr,derr;                                  // err_i during icache load
wire insnerr;                                   // err_i during icache load
wire [127:0] insn;
wire iuncached;
reg [NREGS:0] rf_v;
//reg [15:0] pf_v;
reg im,imb;
reg [5:0] imcd;
reg fxe;
reg nmi1,nmi_edge;
reg StatusHWI;
reg StatusDBG;
reg [7:0] StatusEXL;
assign km = StatusHWI | |StatusEXL;
reg [7:0] GM;            // register group mask
reg [7:0] GMB;
wire [63:0] sr = {32'd0,imb,7'b0,GMB,im,1'b0,km,fxe,4'b0,GM};
wire int_commit;
wire int_pending;
wire sys_commit;
wire dbg_commit;
`ifdef SEGMENTATION
wire [DBW-1:0] spc = (pc[ABW]==1'b1) ? pc[ABW-1:0] :
                     (pc[ABW-1:ABW-4]==4'hF) ? pc[ABW-1:0] : {sregs[3'd7],12'h000} + pc[ABW-1:0];
`else
wire [DBW-1:0] spc = pc;
`endif
wire [DBW-1:0] ppcp16 = ppc + 64'd16;
reg [DBW-1:0] string_pc;
reg stmv_flag;
reg [7:0] asid;
 
wire clk;
 
// Operand registers
wire take_branch;
wire take_branch0;
wire take_branch1;
 
reg [3:0] rf_source [0:NREGS];
//reg [3:0] pf_source [15:0];
 
// instruction queue (ROB)
reg [7:0]  iqentry_v;                    // entry valid?  -- this should be the first bit
reg        iqentry_out  [0:7];   // instruction has been issued to an ALU ... 
reg        iqentry_done [0:7];   // instruction result valid
reg [7:0]  iqentry_cmt;                  // commit result to machine state
reg        iqentry_bt   [0:7];   // branch-taken (used only for branches)
reg        iqentry_br   [0:7];  // branch instruction decode
reg        iqentry_agen [0:7];  // memory address is generated
reg        iqentry_mem  [0:7];   // touches memory: 1 if LW/SW
reg        iqentry_ndx  [0:7];  // TRUE if indexed memory op
reg        iqentry_cas  [0:7];
reg        iqentry_pushpop [0:7];
reg        iqentry_pea  [0:7];
reg        iqentry_cmpmv [0:7];
reg        iqentry_lla  [0:7];  // load linear address
reg        iqentry_tlb  [0:7];
reg        iqentry_jmp  [0:7];   // changes control flow: 1 if BEQ/JALR
reg        iqentry_jmpi [0:7];
reg        iqentry_sync [0:7];  // sync instruction
reg        iqentry_memsb[0:7];
reg        iqentry_memdb[0:7];
reg        iqentry_fp   [0:7];  // is an floating point operation
reg        iqentry_rfw  [0:7];   // writes to register file
reg [DBW-1:0] iqentry_res        [0:7];   // instruction result
reg  [3:0] iqentry_insnsz [0:7];  // the size of the instruction
reg  [3:0] iqentry_cond [0:7];    // predicating condition
reg  [3:0] iqentry_preg [0:7];  // predicate regno
reg  [3:0] iqentry_pred [0:7];    // predicate value
reg        iqentry_p_v  [0:7];   // predicate is valid
reg  [3:0] iqentry_p_s  [0:7];    // predicate source
reg  [7:0] iqentry_op    [0:7];   // instruction opcode
reg  [5:0] iqentry_fn   [0:7];  // instruction function
reg  [2:0] iqentry_renmapno [0:7];        // register rename map number
reg  [6:0] iqentry_tgt   [0:7];   // Rt field or ZERO -- this is the instruction's target (if any)
reg [DBW-1:0] iqentry_a0 [0:7];   // argument 0 (immediate)
reg [DBW-1:0] iqentry_a1 [0:7];   // argument 1
reg [6:0]  iqentry_r1   [0:7];
reg        iqentry_a1_v [0:7];   // arg1 valid
reg  [3:0] iqentry_a1_s  [0:7];   // arg1 source (iq entry # with top bit representing ALU/DRAM bus)
reg [6:0]  iqentry_r2   [0:7];
reg [DBW-1:0] iqentry_a2 [0:7];   // argument 2
reg        iqentry_a2_v [0:7];   // arg2 valid
reg  [3:0] iqentry_a2_s  [0:7];   // arg2 source (iq entry # with top bit representing ALU/DRAM bus)
reg [6:0]  iqentry_r3   [0:7];
reg [DBW-1:0] iqentry_a3 [0:7];   // argument 3
reg        iqentry_a3_v [0:7];   // arg3 valid
reg  [3:0] iqentry_a3_s  [0:7];   // arg3 source (iq entry # with top bit representing ALU/DRAM bus)
reg [6:0]  iqentry_rt   [0:7];
reg [DBW-1:0] iqentry_T [0:7];
reg        iqentry_T_v [0:7];
reg  [3:0] iqentry_T_s [0:7];
reg [DBW-1:0] iqentry_pc [0:7];   // program counter for this instruction
 
reg  [7:0] iqentry_source;
wire  iqentry_imm [0:7];
wire  iqentry_memready [0:7];
wire  iqentry_memopsvalid [0:7];
reg qstomp;
 
wire stomp_all;
reg  [7:0] iqentry_fpissue;
reg  [7:0] iqentry_memissue;
wire iqentry_memissue_head0;
wire iqentry_memissue_head1;
wire iqentry_memissue_head2;
wire iqentry_memissue_head3;
wire iqentry_memissue_head4;
wire iqentry_memissue_head5;
wire iqentry_memissue_head6;
wire iqentry_memissue_head7;
wire  [7:0] iqentry_stomp;
reg  [7:0] iqentry_issue;
wire  [1:0] iqentry_0_islot;
wire  [1:0] iqentry_1_islot;
wire  [1:0] iqentry_2_islot;
wire  [1:0] iqentry_3_islot;
wire  [1:0] iqentry_4_islot;
wire  [1:0] iqentry_5_islot;
wire  [1:0] iqentry_6_islot;
wire  [1:0] iqentry_7_islot;
reg  [1:0] iqentry_islot[0:7];
reg [1:0] iqentry_fpislot[0:7];
 
reg queued1,queued2;
reg queued3;    // for three-way config
reg allowq;
 
wire  [NREGS:1] livetarget;
wire  [NREGS:1] iqentry_0_livetarget;
wire  [NREGS:1] iqentry_1_livetarget;
wire  [NREGS:1] iqentry_2_livetarget;
wire  [NREGS:1] iqentry_3_livetarget;
wire  [NREGS:1] iqentry_4_livetarget;
wire  [NREGS:1] iqentry_5_livetarget;
wire  [NREGS:1] iqentry_6_livetarget;
wire  [NREGS:1] iqentry_7_livetarget;
wire  [NREGS:1] iqentry_0_latestID;
wire  [NREGS:1] iqentry_1_latestID;
wire  [NREGS:1] iqentry_2_latestID;
wire  [NREGS:1] iqentry_3_latestID;
wire  [NREGS:1] iqentry_4_latestID;
wire  [NREGS:1] iqentry_5_latestID;
wire  [NREGS:1] iqentry_6_latestID;
wire  [NREGS:1] iqentry_7_latestID;
wire  [NREGS:1] iqentry_0_cumulative;
wire  [NREGS:1] iqentry_1_cumulative;
wire  [NREGS:1] iqentry_2_cumulative;
wire  [NREGS:1] iqentry_3_cumulative;
wire  [NREGS:1] iqentry_4_cumulative;
wire  [NREGS:1] iqentry_5_cumulative;
wire  [NREGS:1] iqentry_6_cumulative;
wire  [NREGS:1] iqentry_7_cumulative;
 
 
reg  [2:0] tail0;
reg  [2:0] tail1;
reg  [2:0] tail2;   // used only for three-way config
reg  [2:0] head0;
reg  [2:0] head1;
reg  [2:0] head2;        // used only to determine memory-access ordering
reg  [2:0] head3;        // used only to determine memory-access ordering
reg  [2:0] head4;        // used only to determine memory-access ordering
reg  [2:0] head5;        // used only to determine memory-access ordering
reg  [2:0] head6;        // used only to determine memory-access ordering
reg  [2:0] head7;        // used only to determine memory-access ordering
reg  [2:0] headinc;
 
wire  [2:0] missid;
reg   fetchbuf;         // determines which pair to read from & write to
 
reg  [63:0] fetchbuf0_instr;
reg  [DBW-1:0] fetchbuf0_pc;
reg         fetchbuf0_v;
wire        fetchbuf0_mem;
wire        fetchbuf0_jmp;
wire            fetchbuf0_fp;
wire        fetchbuf0_rfw;
wire        fetchbuf0_pfw;
reg  [63:0] fetchbuf1_instr;
reg  [DBW-1:0] fetchbuf1_pc;
reg        fetchbuf1_v;
wire        fetchbuf1_mem;
wire        fetchbuf1_jmp;
wire            fetchbuf1_fp;
wire        fetchbuf1_rfw;
wire        fetchbuf1_pfw;
wire        fetchbuf1_bfw;
reg  [63:0] fetchbuf2_instr;
reg  [DBW-1:0] fetchbuf2_pc;
reg        fetchbuf2_v;
wire        fetchbuf2_mem;
wire        fetchbuf2_jmp;
wire            fetchbuf2_fp;
wire        fetchbuf2_rfw;
wire        fetchbuf2_pfw;
wire        fetchbuf2_bfw;
 
reg [63:0] fetchbufA_instr;
reg [DBW-1:0] fetchbufA_pc;
reg        fetchbufA_v;
reg [63:0] fetchbufB_instr;
reg [DBW-1:0] fetchbufB_pc;
reg        fetchbufB_v;
reg [63:0] fetchbufC_instr;
reg [DBW-1:0] fetchbufC_pc;
reg        fetchbufC_v;
reg [63:0] fetchbufD_instr;
reg [DBW-1:0] fetchbufD_pc;
reg        fetchbufD_v;
 
reg        did_branchback;
reg             did_branchback0;
reg                     did_branchback1;
 
reg        alu0_ld;
reg        alu0_available;
reg        alu0_dataready;
reg  [3:0] alu0_sourceid;
reg  [3:0] alu0_insnsz;
reg  [7:0] alu0_op;
reg  [5:0] alu0_fn;
reg  [3:0] alu0_cond;
reg        alu0_bt;
reg        alu0_cmt;
reg [DBW-1:0] alu0_argA;
reg [DBW-1:0] alu0_argB;
reg [DBW-1:0] alu0_argC;
reg [DBW-1:0] alu0_argT;
reg [DBW-1:0] alu0_argI;
reg  [3:0] alu0_pred;
reg [DBW-1:0] alu0_pc;
reg [DBW-1:0] alu0_bus;
reg  [3:0] alu0_id;
wire  [3:0] alu0_exc;
reg        alu0_v;
wire        alu0_branchmiss;
reg [ABW:0] alu0_misspc;
 
reg        alu1_ld;
reg        alu1_available;
reg        alu1_dataready;
reg  [3:0] alu1_sourceid;
reg  [3:0] alu1_insnsz;
reg  [7:0] alu1_op;
reg  [5:0] alu1_fn;
reg  [3:0] alu1_cond;
reg        alu1_bt;
reg        alu1_cmt;
reg [DBW-1:0] alu1_argA;
reg [DBW-1:0] alu1_argB;
reg [DBW-1:0] alu1_argC;
reg [DBW-1:0] alu1_argT;
reg [DBW-1:0] alu1_argI;
reg  [3:0] alu1_pred;
reg [DBW-1:0] alu1_pc;
reg [DBW-1:0] alu1_bus;
reg  [3:0] alu1_id;
wire  [3:0] alu1_exc;
reg        alu1_v;
wire        alu1_branchmiss;
reg [ABW:0] alu1_misspc;
 
wire jmpi_miss;
reg [ABW-1:0] jmpi_misspc;
wire mem_stringmissx;
reg mem_stringmiss;
wire        branchmiss;
wire [ABW:0] misspc;
 
`ifdef FLOATING_POINT
reg        fp0_ld;
reg        fp0_available;
reg        fp0_dataready;
reg  [3:0] fp0_sourceid;
reg  [7:0] fp0_op;
reg  [5:0] fp0_fn;
reg  [3:0] fp0_cond;
wire        fp0_cmt;
reg             fp0_done;
reg [DBW-1:0] fp0_argA;
reg [DBW-1:0] fp0_argB;
reg [DBW-1:0] fp0_argC;
reg [DBW-1:0] fp0_argI;
reg  [3:0] fp0_pred;
reg [DBW-1:0] fp0_pc;
wire [DBW-1:0] fp0_bus;
wire  [3:0] fp0_id;
wire  [7:0] fp0_exc;
wire        fp0_v;
`endif
 
wire        dram_avail;
reg      [2:0] dram0;    // state of the DRAM request (latency = 4; can have three in pipeline)
reg      [2:0] dram1;    // state of the DRAM request (latency = 4; can have three in pipeline)
reg      [2:0] dram2;    // state of the DRAM request (latency = 4; can have three in pipeline)
reg  [2:0] tlb_state;
reg [3:0] tlb_id;
reg [3:0] tlb_op;
reg [3:0] tlb_regno;
reg [8:0] tlb_tgt;
reg [DBW-1:0] tlb_data;
 
wire [DBW-1:0] tlb_dato;
reg dram0_owns_bus;
reg [DBW-1:0] dram0_data;
reg [DBW-1:0] dram0_datacmp;
reg [DBW-1:0] dram0_addr;
reg [DBW-1:0] dram0_seg;        // value of segment register associated with memory operation
reg [ABW-1:12] dram0_lmt;       // value of segment limit associated with memory operation
reg  [7:0] dram0_op;
reg  [5:0] dram0_fn;
reg  [8:0] dram0_tgt;
reg  [3:0] dram0_id;
reg  [3:0] dram0_exc;
reg [ABW-1:0] dram0_misspc;
reg dram1_owns_bus;
reg [DBW-1:0] dram1_data;
reg [DBW-1:0] dram1_datacmp;
reg [DBW-1:0] dram1_addr;
reg  [7:0] dram1_op;
reg  [5:0] dram1_fn;
reg  [6:0] dram1_tgt;
reg  [3:0] dram1_id;
reg  [3:0] dram1_exc;
reg [DBW-1:0] dram2_data;
reg [DBW-1:0] dram2_datacmp;
reg [DBW-1:0] dram2_addr;
reg  [7:0] dram2_op;
reg  [5:0] dram2_fn;
reg  [6:0] dram2_tgt;
reg  [3:0] dram2_id;
reg  [3:0] dram2_exc;
 
reg [DBW-1:0] dram_bus;
reg  [6:0] dram_tgt;
reg  [3:0] dram_id;
reg  [3:0] dram_exc;
reg        dram_v;
 
reg [DBW-1:0] index;
reg [DBW-1:0] src_addr,dst_addr;
wire mem_issue;
 
wire        outstanding_stores;
reg [DBW-1:0] I; // instruction count
 
wire        commit0_v;
wire  [3:0] commit0_id;
wire  [6:0] commit0_tgt;
wire [DBW-1:0] commit0_bus;
wire        commit1_v;
wire  [3:0] commit1_id;
wire  [6:0] commit1_tgt;
wire [DBW-1:0] commit1_bus;
wire limit_cmt;
wire committing2;
 
wire [63:0] alu0_divq;
wire [63:0] alu0_rem;
wire alu0_div_done;
 
wire [63:0] alu1_divq;
wire [63:0] alu1_rem;
wire alu1_div_done;
 
wire [127:0] alu0_prod;
wire alu0_mult_done;
wire [127:0] alu1_prod;
wire alu1_mult_done;
 
reg exception_set;
 
//-----------------------------------------------------------------------------
// Debug
//-----------------------------------------------------------------------------
 
wire [DBW-1:0] dbg_stat1x;
reg [DBW-1:0] dbg_stat;
reg [DBW-1:0] dbg_ctrl;
reg [ABW-1:0] dbg_adr0;
reg [ABW-1:0] dbg_adr1;
reg [ABW-1:0] dbg_adr2;
reg [ABW-1:0] dbg_adr3;
reg dbg_imatchA0,dbg_imatchA1,dbg_imatchA2,dbg_imatchA3,dbg_imatchA;
reg dbg_imatchB0,dbg_imatchB1,dbg_imatchB2,dbg_imatchB3,dbg_imatchB;
 
wire dbg_lmatch0 =
                        dbg_ctrl[0] && dbg_ctrl[17:16]==2'b11 && dram0_addr[AMSB:3]==dbg_adr0[AMSB:3] &&
                                ((dbg_ctrl[19:18]==2'b00 && dram0_addr[2:0]==dbg_adr0[2:0]) ||
                                 (dbg_ctrl[19:18]==2'b01 && dram0_addr[2:1]==dbg_adr0[2:1]) ||
                                 (dbg_ctrl[19:18]==2'b10 && dram0_addr[2]==dbg_adr0[2]) ||
                                 dbg_ctrl[19:18]==2'b11)
                                 ;
wire dbg_lmatch1 =
             dbg_ctrl[1] && dbg_ctrl[21:20]==2'b11 && dram0_addr[AMSB:3]==dbg_adr1[AMSB:3] &&
                 ((dbg_ctrl[23:22]==2'b00 && dram0_addr[2:0]==dbg_adr1[2:0]) ||
                  (dbg_ctrl[23:22]==2'b01 && dram0_addr[2:1]==dbg_adr1[2:1]) ||
                  (dbg_ctrl[23:22]==2'b10 && dram0_addr[2]==dbg_adr1[2]) ||
                  dbg_ctrl[23:22]==2'b11)
                  ;
wire dbg_lmatch2 =
               dbg_ctrl[2] && dbg_ctrl[25:24]==2'b11 && dram0_addr[AMSB:3]==dbg_adr2[AMSB:3] &&
                   ((dbg_ctrl[27:26]==2'b00 && dram0_addr[2:0]==dbg_adr2[2:0]) ||
                    (dbg_ctrl[27:26]==2'b01 && dram0_addr[2:1]==dbg_adr2[2:1]) ||
                    (dbg_ctrl[27:26]==2'b10 && dram0_addr[2]==dbg_adr2[2]) ||
                    dbg_ctrl[27:26]==2'b11)
                    ;
wire dbg_lmatch3 =
                 dbg_ctrl[3] && dbg_ctrl[29:28]==2'b11 && dram0_addr[AMSB:3]==dbg_adr3[AMSB:3] &&
                     ((dbg_ctrl[31:30]==2'b00 && dram0_addr[2:0]==dbg_adr3[2:0]) ||
                      (dbg_ctrl[31:30]==2'b01 && dram0_addr[2:1]==dbg_adr3[2:1]) ||
                      (dbg_ctrl[31:30]==2'b10 && dram0_addr[2]==dbg_adr3[2]) ||
                      dbg_ctrl[31:30]==2'b11)
                      ;
wire dbg_lmatch = dbg_lmatch0|dbg_lmatch1|dbg_lmatch2|dbg_lmatch3;
 
wire dbg_smatch0 =
                        dbg_ctrl[0] && dbg_ctrl[17:16]==2'b11 && dram0_addr[AMSB:3]==dbg_adr0[AMSB:3] &&
                                ((dbg_ctrl[19:18]==2'b00 && dram0_addr[2:0]==dbg_adr0[2:0]) ||
                                 (dbg_ctrl[19:18]==2'b01 && dram0_addr[2:1]==dbg_adr0[2:1]) ||
                                 (dbg_ctrl[19:18]==2'b10 && dram0_addr[2]==dbg_adr0[2]) ||
                                 dbg_ctrl[19:18]==2'b11)
                                 ;
wire dbg_smatch1 =
             dbg_ctrl[1] && dbg_ctrl[21:20]==2'b11 && dram0_addr[AMSB:3]==dbg_adr1[AMSB:3] &&
                 ((dbg_ctrl[23:22]==2'b00 && dram0_addr[2:0]==dbg_adr1[2:0]) ||
                  (dbg_ctrl[23:22]==2'b01 && dram0_addr[2:1]==dbg_adr1[2:1]) ||
                  (dbg_ctrl[23:22]==2'b10 && dram0_addr[2]==dbg_adr1[2]) ||
                  dbg_ctrl[23:22]==2'b11)
                  ;
wire dbg_smatch2 =
               dbg_ctrl[2] && dbg_ctrl[25:24]==2'b11 && dram0_addr[AMSB:3]==dbg_adr2[AMSB:3] &&
                   ((dbg_ctrl[27:26]==2'b00 && dram0_addr[2:0]==dbg_adr2[2:0]) ||
                    (dbg_ctrl[27:26]==2'b01 && dram0_addr[2:1]==dbg_adr2[2:1]) ||
                    (dbg_ctrl[27:26]==2'b10 && dram0_addr[2]==dbg_adr2[2]) ||
                    dbg_ctrl[27:26]==2'b11)
                    ;
wire dbg_smatch3 =
                 dbg_ctrl[3] && dbg_ctrl[29:28]==2'b11 && dram0_addr[AMSB:3]==dbg_adr3[AMSB:3] &&
                     ((dbg_ctrl[31:30]==2'b00 && dram0_addr[2:0]==dbg_adr3[2:0]) ||
                      (dbg_ctrl[31:30]==2'b01 && dram0_addr[2:1]==dbg_adr3[2:1]) ||
                      (dbg_ctrl[31:30]==2'b10 && dram0_addr[2]==dbg_adr3[2]) ||
                      dbg_ctrl[31:30]==2'b11)
                      ;
wire dbg_smatch = dbg_smatch0|dbg_smatch1|dbg_smatch2|dbg_smatch3;
 
wire dbg_stat0 = dbg_imatchA0 | dbg_imatchB0 | dbg_lmatch0 | dbg_smatch0;
wire dbg_stat1 = dbg_imatchA1 | dbg_imatchB1 | dbg_lmatch1 | dbg_smatch1;
wire dbg_stat2 = dbg_imatchA2 | dbg_imatchB2 | dbg_lmatch2 | dbg_smatch2;
wire dbg_stat3 = dbg_imatchA3 | dbg_imatchB3 | dbg_lmatch3 | dbg_smatch3;
assign dbg_stat1x = {dbg_stat3,dbg_stat2,dbg_stat1,dbg_stat0};
wire debug_on = |dbg_ctrl[3:0]|dbg_ctrl[7];
 
reg [11:0] spr_bir;
 
always @(StatusHWI or StatusDBG or StatusEXL)
if (StatusHWI)
    mode = 2'd1;
else if (StatusDBG)
    mode = 2'd3;
else if (StatusEXL)
    mode = 2'd2;
else
    mode = 2'd0;
 
//
// BRANCH-MISS LOGIC: livetarget
//
// livetarget implies that there is a not-to-be-stomped instruction that targets the register in question
// therefore, if it is zero it implies the rf_v value should become VALID on a branchmiss
// 
/*
Thor_livetarget #(NREGS) ultgt1
(
        iqentry_v,
        iqentry_stomp,
        iqentry_cmt,
        iqentry_tgt[0],
        iqentry_tgt[1],
        iqentry_tgt[2],
        iqentry_tgt[3],
        iqentry_tgt[4],
        iqentry_tgt[5],
        iqentry_tgt[6],
        iqentry_tgt[7],
        livetarget,
        iqentry_0_livetarget,
        iqentry_1_livetarget,
        iqentry_2_livetarget,
        iqentry_3_livetarget,
        iqentry_4_livetarget,
        iqentry_5_livetarget,
        iqentry_6_livetarget,
        iqentry_7_livetarget
);
 
//
// BRANCH-MISS LOGIC: latestID
//
// latestID is the instruction queue ID of the newest instruction (latest) that targets
// a particular register.  looks a lot like scheduling logic, but in reverse.
//
 
assign iqentry_0_latestID = ((missid == 3'd0)|| ((iqentry_0_livetarget & iqentry_1_cumulative) == {NREGS{1'b0}}))
                                ? iqentry_0_livetarget
                                : {NREGS{1'b0}};
assign iqentry_0_cumulative = (missid == 3'd0)
                                ? iqentry_0_livetarget
                                : iqentry_0_livetarget | iqentry_1_cumulative;
 
assign iqentry_1_latestID = ((missid == 3'd1)|| ((iqentry_1_livetarget & iqentry_2_cumulative) == {NREGS{1'b0}}))
                                ? iqentry_1_livetarget
                                : {NREGS{1'b0}};
assign iqentry_1_cumulative = (missid == 3'd1)
                                ? iqentry_1_livetarget
                                : iqentry_1_livetarget | iqentry_2_cumulative;
 
assign iqentry_2_latestID = ((missid == 3'd2) || ((iqentry_2_livetarget & iqentry_3_cumulative) == {NREGS{1'b0}}))
                                ? iqentry_2_livetarget
                                : {NREGS{1'b0}};
assign iqentry_2_cumulative = (missid == 3'd2)
                                ? iqentry_2_livetarget
                                : iqentry_2_livetarget | iqentry_3_cumulative;
 
assign iqentry_3_latestID = ((missid == 3'd3)|| ((iqentry_3_livetarget & iqentry_4_cumulative) == {NREGS{1'b0}}))
                                ? iqentry_3_livetarget
                                : {NREGS{1'b0}};
assign iqentry_3_cumulative = (missid == 3'd3)
                                ? iqentry_3_livetarget
                                : iqentry_3_livetarget | iqentry_4_cumulative;
 
assign iqentry_4_latestID = ((missid == 3'd4) || ((iqentry_4_livetarget & iqentry_5_cumulative) == {NREGS{1'b0}}))
                                ? iqentry_4_livetarget
                                : {NREGS{1'b0}};
assign iqentry_4_cumulative = (missid == 3'd4)
                                ? iqentry_4_livetarget
                                : iqentry_4_livetarget | iqentry_5_cumulative;
 
assign iqentry_5_latestID = ((missid == 3'd5)|| ((iqentry_5_livetarget & iqentry_6_cumulative) == {NREGS{1'b0}}))
                                ? iqentry_5_livetarget
                                : 287'd0;
assign iqentry_5_cumulative = (missid == 3'd5)
                                ? iqentry_5_livetarget
                                : iqentry_5_livetarget | iqentry_6_cumulative;
 
assign iqentry_6_latestID = ((missid == 3'd6) || ((iqentry_6_livetarget & iqentry_7_cumulative) == {NREGS{1'b0}}))
                                ? iqentry_6_livetarget
                                : {NREGS{1'b0}};
assign iqentry_6_cumulative = (missid == 3'd6)
                                ? iqentry_6_livetarget
                                : iqentry_6_livetarget | iqentry_7_cumulative;
 
assign iqentry_7_latestID = ((missid == 3'd7) || ((iqentry_7_livetarget & iqentry_0_cumulative) == {NREGS{1'b0}}))
                                ? iqentry_7_livetarget
                                : {NREGS{1'b0}};
assign iqentry_7_cumulative = (missid==3'd7)
                                ? iqentry_7_livetarget
                                : iqentry_7_livetarget | iqentry_0_cumulative;
 
assign
        iqentry_source[0] = | iqentry_0_latestID,
        iqentry_source[1] = | iqentry_1_latestID,
        iqentry_source[2] = | iqentry_2_latestID,
        iqentry_source[3] = | iqentry_3_latestID,
        iqentry_source[4] = | iqentry_4_latestID,
        iqentry_source[5] = | iqentry_5_latestID,
        iqentry_source[6] = | iqentry_6_latestID,
        iqentry_source[7] = | iqentry_7_latestID;
*/
always @*
begin
iqentry_source = 8'h00;
if (missid==head0) begin
    if (iqentry_v[head0] && !iqentry_stomp[head0])
        iqentry_source[head0] = !fnRegIsAutoValid(iqentry_tgt[head0]);
end
else if (missid==head1) begin
    if (iqentry_v[head0] && !iqentry_stomp[head0])
        iqentry_source[head0] = !fnRegIsAutoValid(iqentry_tgt[head0]);
    if (iqentry_v[head1] && !iqentry_stomp[head1])
        iqentry_source[head1] = !fnRegIsAutoValid(iqentry_tgt[head1]);
end
else if (missid==head2) begin
    if (iqentry_v[head0] && !iqentry_stomp[head0])
        iqentry_source[head0] = !fnRegIsAutoValid(iqentry_tgt[head0]);
    if (iqentry_v[head1] && !iqentry_stomp[head1])
        iqentry_source[head1] = !fnRegIsAutoValid(iqentry_tgt[head1]);
    if (iqentry_v[head2] && !iqentry_stomp[head2])
        iqentry_source[head2] = !fnRegIsAutoValid(iqentry_tgt[head2]);
end
else if (missid==head3) begin
    if (iqentry_v[head0] && !iqentry_stomp[head0])
        iqentry_source[head0] = !fnRegIsAutoValid(iqentry_tgt[head0]);
    if (iqentry_v[head1] && !iqentry_stomp[head1])
        iqentry_source[head1] = !fnRegIsAutoValid(iqentry_tgt[head1]);
    if (iqentry_v[head2] && !iqentry_stomp[head2])
        iqentry_source[head2] = !fnRegIsAutoValid(iqentry_tgt[head2]);
    if (iqentry_v[head3] && !iqentry_stomp[head3])
        iqentry_source[head3] = !fnRegIsAutoValid(iqentry_tgt[head3]);
end
else if (missid==head4) begin
    if (iqentry_v[head0] && !iqentry_stomp[head0])
        iqentry_source[head0] = !fnRegIsAutoValid(iqentry_tgt[head0]);
    if (iqentry_v[head1] && !iqentry_stomp[head1])
        iqentry_source[head1] = !fnRegIsAutoValid(iqentry_tgt[head1]);
    if (iqentry_v[head2] && !iqentry_stomp[head2])
        iqentry_source[head2] = !fnRegIsAutoValid(iqentry_tgt[head2]);
    if (iqentry_v[head3] && !iqentry_stomp[head3])
        iqentry_source[head3] = !fnRegIsAutoValid(iqentry_tgt[head3]);
    if (iqentry_v[head4] && !iqentry_stomp[head4])
        iqentry_source[head4] = !fnRegIsAutoValid(iqentry_tgt[head4]);
end
else if (missid==head5) begin
    if (iqentry_v[head0] && !iqentry_stomp[head0])
        iqentry_source[head0] = !fnRegIsAutoValid(iqentry_tgt[head0]);
    if (iqentry_v[head1] && !iqentry_stomp[head1])
        iqentry_source[head1] = !fnRegIsAutoValid(iqentry_tgt[head1]);
    if (iqentry_v[head2] && !iqentry_stomp[head2])
        iqentry_source[head2] = !fnRegIsAutoValid(iqentry_tgt[head2]);
    if (iqentry_v[head3] && !iqentry_stomp[head3])
        iqentry_source[head3] = !fnRegIsAutoValid(iqentry_tgt[head3]);
    if (iqentry_v[head4] && !iqentry_stomp[head4])
        iqentry_source[head4] = !fnRegIsAutoValid(iqentry_tgt[head4]);
    if (iqentry_v[head5] && !iqentry_stomp[head5])
        iqentry_source[head5] = !fnRegIsAutoValid(iqentry_tgt[head5]);
end
else if (missid==head6) begin
    if (iqentry_v[head0] && !iqentry_stomp[head0])
        iqentry_source[head0] = !fnRegIsAutoValid(iqentry_tgt[head0]);
    if (iqentry_v[head1] && !iqentry_stomp[head1])
        iqentry_source[head1] = !fnRegIsAutoValid(iqentry_tgt[head1]);
    if (iqentry_v[head2] && !iqentry_stomp[head2])
        iqentry_source[head2] = !fnRegIsAutoValid(iqentry_tgt[head2]);
    if (iqentry_v[head3] && !iqentry_stomp[head3])
        iqentry_source[head3] = !fnRegIsAutoValid(iqentry_tgt[head3]);
    if (iqentry_v[head4] && !iqentry_stomp[head4])
        iqentry_source[head4] = !fnRegIsAutoValid(iqentry_tgt[head4]);
    if (iqentry_v[head5] && !iqentry_stomp[head5])
        iqentry_source[head5] = !fnRegIsAutoValid(iqentry_tgt[head5]);
    if (iqentry_v[head6] && !iqentry_stomp[head6])
        iqentry_source[head6] = !fnRegIsAutoValid(iqentry_tgt[head6]);
end
else if (missid==head7) begin
    if (iqentry_v[head0] && !iqentry_stomp[head0])
        iqentry_source[head0] = !fnRegIsAutoValid(iqentry_tgt[head0]);
    if (iqentry_v[head1] && !iqentry_stomp[head1])
        iqentry_source[head1] = !fnRegIsAutoValid(iqentry_tgt[head1]);
    if (iqentry_v[head2] && !iqentry_stomp[head2])
        iqentry_source[head2] = !fnRegIsAutoValid(iqentry_tgt[head2]);
    if (iqentry_v[head3] && !iqentry_stomp[head3])
        iqentry_source[head3] = !fnRegIsAutoValid(iqentry_tgt[head3]);
    if (iqentry_v[head4] && !iqentry_stomp[head4])
        iqentry_source[head4] = !fnRegIsAutoValid(iqentry_tgt[head4]);
    if (iqentry_v[head5] && !iqentry_stomp[head5])
        iqentry_source[head5] = !fnRegIsAutoValid(iqentry_tgt[head5]);
    if (iqentry_v[head6] && !iqentry_stomp[head6])
        iqentry_source[head6] = !fnRegIsAutoValid(iqentry_tgt[head6]);
    if (iqentry_v[head7] && !iqentry_stomp[head7])
        iqentry_source[head7] = !fnRegIsAutoValid(iqentry_tgt[head7]);
end
end
 
//assign iqentry_0_islot = iqentry_islot[0];
//assign iqentry_1_islot = iqentry_islot[1];
//assign iqentry_2_islot = iqentry_islot[2];
//assign iqentry_3_islot = iqentry_islot[3];
//assign iqentry_4_islot = iqentry_islot[4];
//assign iqentry_5_islot = iqentry_islot[5];
//assign iqentry_6_islot = iqentry_islot[6];
//assign iqentry_7_islot = iqentry_islot[7];
 
// A single instruction can require 3 read ports. Only a total of four read
// ports are supported because most of the time that's enough.
// If there aren't enough read ports available then the second instruction
// isn't enqueued (it'll be enqueued in the next cycle).
reg [1:0] ports_avail;  // available read ports for instruction #3.
reg [6:0] pRa0,pRb0,pRa1,pRb1,pRt0,pRt1;
wire [DBW-1:0] prfoa0,prfob0,prfoa1,prfob1;
wire [DBW-1:0] prfot0,prfot1;
 
wire [6:0] Ra0 = fnRa(fetchbuf0_instr);
wire [6:0] Rb0 = fnRb(fetchbuf0_instr);
wire [6:0] Rc0 = fnRc(fetchbuf0_instr);
wire [6:0] Ra1 = fnRa(fetchbuf1_instr);
wire [6:0] Rb1 = fnRb(fetchbuf1_instr);
wire [6:0] Rc1 = fnRc(fetchbuf1_instr);
wire [6:0] Rt0 = fnTargetReg(fetchbuf0_instr);
wire [6:0] Rt1 = fnTargetReg(fetchbuf1_instr);
always @*
begin
    pRt0 = Rt0;
    pRt1 = Rt1;
    rfot0 = prfot0;
    rfot1 = prfot1;
    case(fetchbuf0_v ? fnNumReadPorts(fetchbuf0_instr) : 2'd0)
    2'd0:   begin
            pRa0 = 7'd0;
            pRb0 = Rc1;
            pRa1 = Ra1;
            pRb1 = Rb1;
            rfoa0 = 64'd0;
            rfob0 = 64'd0;
            rfoc0 = 64'd0;
            rfoa1 = prfoa1;
            rfob1 = prfob1;
            rfoc1 = prfob0;
            ports_avail = 2'd3;
            end
    2'd1:   begin
            pRa0 = Ra0;
            pRb0 = Rc1;
            pRa1 = Ra1;
            pRb1 = Rb1;
            rfoa0 = prfoa0;
            rfob0 = 64'd0;
            rfoc0 = 64'd0;
            rfoa1 = prfoa1;
            rfob1 = prfob1;
            rfoc1 = prfob0;
            ports_avail = 2'd3;
            end
    2'd2:   begin
            pRa0 = Ra0;
            pRb0 = Rb0;
            pRa1 = Ra1;
            pRb1 = Rb1;
            rfoa0 = prfoa0;
            rfob0 = prfob0;
            rfoc0 = 64'd0;
            rfoa1 = prfoa1;
            rfob1 = prfob1;
            rfoc1 = 64'd0;
            ports_avail = 2'd2;
            end
    2'd3:   begin
            pRa0 = Ra0;
            pRb0 = Rb0;
            pRa1 = Rc0;
            pRb1 = Ra1;
            rfoa0 = prfoa0;
            rfob0 = prfob0;
            rfoc0 = prfoa1;
            rfoa1 = prfob1;
            rfob1 = 64'd0;
            rfoc1 = 64'd0;
            ports_avail = 2'd1;
            end
    endcase
end
 
/*
wire [8:0] Rb0 = ((fnNumReadPorts(fetchbuf0_instr) < 3'd2) || !fetchbuf0_v) ? {1'b0,fetchbuf1_instr[`INSTRUCTION_RC]} :
                                fnRb(fetchbuf0_instr);
wire [8:0] Ra1 = (!fetchbuf0_v || fnNumReadPorts(fetchbuf0_instr) < 3'd3) ? fnRa(fetchbuf1_instr) :
                                        fetchbuf0_instr[`INSTRUCTION_RC];
wire [8:0] Rb1 = (fnNumReadPorts(fetchbuf1_instr) < 3'd2 && fetchbuf0_v) ? fnRa(fetchbuf1_instr):fnRb(fetchbuf1_instr);
*/
function [7:0] fnOpcode;
input [63:0] ins;
fnOpcode = (ins[3:0]==4'h0 && ins[7:4] > 4'h1 && ins[7:4] < 4'h9) ? `IMM :
                                                ins[7:0]==8'h10 ? `NOP : ins[15:8];
endfunction
 
wire [7:0] opcode0 = fnOpcode(fetchbuf0_instr);
wire [7:0] opcode1 = fnOpcode(fetchbuf1_instr);
wire [3:0] cond0 = fetchbuf0_instr[3:0];
wire [3:0] cond1 = fetchbuf1_instr[3:0];
wire [3:0] Pn0 = fetchbuf0_instr[7:4];
wire [3:0] Pt0 = fetchbuf0_instr[11:8];
wire [3:0] Pn1 = fetchbuf1_instr[7:4];
wire [3:0] Pt1 = fetchbuf1_instr[11:8];
 
wire [6:0] r27 = 7'd27 + mode;
 
function [6:0] fnRa;
input [63:0] isn;
        case(isn[15:8])
        `RTS2:  fnRa = 7'h51;
        `RTI:   fnRa = 7'h5E;
        `RTD:   fnRa = 7'h5B;
        `RTE:   fnRa = 7'h5D;
        `JSR,`JSRS,`JSRZ,`SYS,`INT,`RTS:
                fnRa = {3'h5,isn[23:20]};
        `TLB:  fnRa = {1'b0,isn[29:24]};
        `P:    fnRa = 7'h70;
        `LOOP:  fnRa = 7'h73;
        `PUSH:   fnRa = r27;
`ifdef STACKOPS
        `PEA,`POP,`LINK:   fnRa = r27;
`endif
    `MFSPR,`MOVS:
        if (isn[`INSTRUCTION_RA]==`USP)
            fnRa = 7'd27;
        else
            fnRa = {1'b1,isn[`INSTRUCTION_RA]};
        default:
               if (isn[`INSTRUCTION_RA]==6'd27)
                   fnRa = r27;
               else
                   fnRa = {1'b0,isn[`INSTRUCTION_RA]};
        endcase
endfunction
 
function [6:0] fnRb;
input [63:0] isn;
        case(isn[15:8])
//      `LOOP:  fnRb = 7'h73;
//      `RTS,`STP,`TLB,`POP:   fnRb = 7'd0;
        `JSR,`JSRS,`JSRZ,`SYS,`INT:
                fnRb = {3'h5,isn[23:20]};
        `SWS:  if (isn[27:22]==`USP)
                   fnRb = {1'b0,6'd27};
               else
                   fnRb = {1'b1,isn[27:22]};
        `PUSH:  fnRb = isn[22:16];
`ifdef STACKOPS
        `LINK:  fnRb = {1'b0,isn[27:22]};
        `PEA:   fnRb = {1'b0,isn[21:16]};
`endif
        default:
           if (isn[`INSTRUCTION_RB]==6'd27)
               fnRb = r27;
           else
               fnRb = {1'b0,isn[`INSTRUCTION_RB]};
        endcase
endfunction
 
function [6:0] fnRc;
input [63:0] isn;
if (isn[`INSTRUCTION_RC]==6'd27)
    fnRc = r27;
else
    fnRc = {1'b0,isn[`INSTRUCTION_RC]};
endfunction
 
function [3:0] fnCar;
input [63:0] isn;
        case(isn[15:8])
        `RTS2:  fnCar = 4'h1;
        `RTI:   fnCar = 4'hE;
        `RTD:   fnCar = 4'hB;
        `RTE:   fnCar = 4'hD;
        `JSR,`JSRS,`JSRZ,`SYS,`INT,`RTS:
                fnCar = {isn[23:20]};
        default:        fnCar = 4'h0;
        endcase
endfunction
 
function [5:0] fnFunc;
input [63:0] isn;
case(isn[15:8])
`BITFIELD:      fnFunc = isn[43:40];
`R:     fnFunc = isn[31:28];
`R2:    fnFunc = isn[31:28];
`DOUBLE_R:  fnFunc = isn[31:28];
`SINGLE_R:  fnFunc = isn[31:28];
8'h10:  fnFunc = isn[31:28];
8'h11:  fnFunc = isn[31:28];
8'h12:  fnFunc = isn[31:28];
8'h13:  fnFunc = isn[31:28];
8'h14:  fnFunc = isn[31:28];
8'h15:  fnFunc = isn[31:28];
8'h16:  fnFunc = isn[31:28];
8'h17:  fnFunc = isn[31:28];
8'h18:  fnFunc = isn[31:28];
8'h19:  fnFunc = isn[31:28];
8'h1A:  fnFunc = isn[31:28];
8'h1B:  fnFunc = isn[31:28];
8'h1C:  fnFunc = isn[31:28];
8'h1D:  fnFunc = isn[31:28];
8'h1E:  fnFunc = isn[31:28];
8'h1F:  fnFunc = isn[31:28];
8'h00:  fnFunc = isn[23:22];
8'h01:  fnFunc = isn[23:22];
8'h02:  fnFunc = isn[23:22];
8'h03:  fnFunc = isn[23:22];
8'h04:  fnFunc = isn[23:22];
8'h05:  fnFunc = isn[23:22];
8'h06:  fnFunc = isn[23:22];
8'h07:  fnFunc = isn[23:22];
8'h08:  fnFunc = isn[23:22];
8'h09:  fnFunc = isn[23:22];
8'h0A:  fnFunc = isn[23:22];
8'h0B:  fnFunc = isn[23:22];
8'h0C:  fnFunc = isn[23:22];
8'h0D:  fnFunc = isn[23:22];
8'h0E:  fnFunc = isn[23:22];
8'h0F:  fnFunc = isn[23:22];
`INC:   fnFunc = {isn[39:37],isn[24:22]};
`TLB:   fnFunc = isn[19:16];
`RTS:   fnFunc = isn[19:16];   // used to pass a small immediate
`CACHE: fnFunc = isn[31:26];
`PUSH,`PEA: fnFunc = km ? 6'b0 : 6'b110000; // select segment register #6
`JMPI:  fnFunc = {isn[39:37],1'b0,isn[27:26]};
`JMPIX: fnFunc = {isn[39:37],1'b0,isn[33:32]};
default:
        fnFunc = isn[39:34];
endcase
endfunction
 
// Returns true if the operation is limited to ALU #0
function fnIsAlu0Op;
input [7:0] opcode;
input [5:0] func;
case(opcode)
`R:
    case(func)
    `CNTLZ,`CNTLO,`CNTPOP:  fnIsAlu0Op = `TRUE;
    `ABS,`SGN,`ZXB,`ZXC,`ZXH,`SXB,`SXC,`SXH:  fnIsAlu0Op = `TRUE;
    default:    fnIsAlu0Op = `FALSE;
    endcase
`R2:    fnIsAlu0Op = `TRUE;
`RR:
    case(func)
    `DIV,`DIVU: fnIsAlu0Op = `TRUE;
    `MOD,`MODU: fnIsAlu0Op = `TRUE;
    `MIN,`MAX:  fnIsAlu0Op = `TRUE;
    default:    fnIsAlu0Op = `FALSE;
    endcase
`BCD:       fnIsAlu0Op = `TRUE;
`DIVI,`DIVUI:   fnIsAlu0Op = `TRUE;
`MODI,`MODUI:   fnIsAlu0Op = `TRUE;
//`DOUBLE:    fnIsAlu0Op = `TRUE;
`SHIFT:     fnIsAlu0Op = `TRUE;
`BITFIELD:  fnIsAlu0Op = `TRUE;
default:    fnIsAlu0Op = `FALSE;
endcase
endfunction
 
// Returns TRUE if the alu will be valid immediately
//
function fnAluValid;
input [7:0] opcode;
input [5:0] func;
case(opcode)
`R: fnAluValid = `TRUE;
`RR:
    case(func)
    `MUL,`MULU,`DIV,`DIVU,`MOD,`MODU: fnAluValid = `FALSE;
    default:    fnAluValid = `TRUE;
    endcase
`MULI,`MULUI,`DIVI,`DIVUI,`MODI,`MODUI:   fnAluValid = `FALSE;
default:    fnAluValid = `TRUE;
endcase
endfunction
 
Thor_regfile2w6r #(DBW) urf1
(
        .clk(clk),
        .rclk(~clk),
        .wr0(commit0_v && ~commit0_tgt[6]),
        .wr1(commit1_v && ~commit1_tgt[6]),
        .wa0(commit0_tgt[5:0]),
        .wa1(commit1_tgt[5:0]),
        .ra0(pRa0[5:0]),
        .ra1(pRb0[5:0]),
        .ra2(pRa1[5:0]),
        .ra3(pRb1[5:0]),
        .ra4(pRt0[5:0]),
        .ra5(pRt1[5:0]),
        .i0(commit0_bus),
        .i1(commit1_bus),
        .o0(prfoa0),
        .o1(prfob0),
        .o2(prfoa1),
        .o3(prfob1),
        .o4(prfot0),
        .o5(prfot1)
);
 
wire [63:0] cregs0 = fnCar(fetchbuf0_instr)==4'd0 ? 64'd0 : fnCar(fetchbuf0_instr)==4'hF ? fetchbuf0_pc : cregs[fnCar(fetchbuf0_instr)];
wire [63:0] cregs1 = fnCar(fetchbuf1_instr)==4'd0 ? 64'd0 : fnCar(fetchbuf1_instr)==4'hF ? fetchbuf1_pc : cregs[fnCar(fetchbuf1_instr)];
//
// 1 if the the operand is automatically valid, 
// 0 if we need a RF value
function fnSource1_v;
input [7:0] opcode;
        case(opcode)
        `SEI,`CLI,`MEMSB,`MEMDB,`SYNC,`NOP,`STP:
                                        fnSource1_v = 1'b1;
        `LDI,`LDIS,`IMM:        fnSource1_v = 1'b1;
        default:
           case(opcode[7:4])
       `BR:             fnSource1_v = 1'b1;
           default:    fnSource1_v = 1'b0;
           endcase
        endcase
endfunction
 
//
// 1 if the the operand is automatically valid, 
// 0 if we need a RF value
function fnSource2_v;
input [7:0] opcode;
input [5:0] func;
        case(opcode)
        `R,`P:          fnSource2_v = 1'b1;
        `LDI,`LDIS,`IMM,`NOP,`STP:              fnSource2_v = 1'b1;
        `SEI,`CLI,`MEMSB,`MEMDB,`SYNC:
                                        fnSource2_v = 1'b1;
        `RTI,`RTD,`RTE,`JMPI:   fnSource2_v = 1'b1;
        // TST
        8'h00:                  fnSource2_v = 1'b1;
        8'h01:                  fnSource2_v = 1'b1;
        8'h02:                  fnSource2_v = 1'b1;
        8'h03:                  fnSource2_v = 1'b1;
        8'h04:                  fnSource2_v = 1'b1;
        8'h05:                  fnSource2_v = 1'b1;
        8'h06:                  fnSource2_v = 1'b1;
        8'h07:                  fnSource2_v = 1'b1;
        8'h08:                  fnSource2_v = 1'b1;
        8'h09:                  fnSource2_v = 1'b1;
        8'h0A:                  fnSource2_v = 1'b1;
        8'h0B:                  fnSource2_v = 1'b1;
        8'h0C:                  fnSource2_v = 1'b1;
        8'h0D:                  fnSource2_v = 1'b1;
        8'h0E:                  fnSource2_v = 1'b1;
        8'h0F:                  fnSource2_v = 1'b1;
        `ADDI,`ADDUI,`ADDUIS:
                        fnSource2_v = 1'b1;
        `_2ADDUI,`_4ADDUI,`_8ADDUI,`_16ADDUI:
                                        fnSource2_v = 1'b1;
        `SUBI,`SUBUI:   fnSource2_v = 1'b1;
        // CMPI
        8'h20:                  fnSource2_v = 1'b1;
        8'h21:                  fnSource2_v = 1'b1;
        8'h22:                  fnSource2_v = 1'b1;
        8'h23:                  fnSource2_v = 1'b1;
        8'h24:                  fnSource2_v = 1'b1;
        8'h25:                  fnSource2_v = 1'b1;
        8'h26:                  fnSource2_v = 1'b1;
        8'h27:                  fnSource2_v = 1'b1;
        8'h28:                  fnSource2_v = 1'b1;
        8'h29:                  fnSource2_v = 1'b1;
        8'h2A:                  fnSource2_v = 1'b1;
        8'h2B:                  fnSource2_v = 1'b1;
        8'h2C:                  fnSource2_v = 1'b1;
        8'h2D:                  fnSource2_v = 1'b1;
        8'h2E:                  fnSource2_v = 1'b1;
        8'h2F:                  fnSource2_v = 1'b1;
        // BR
    8'h30:            fnSource2_v = 1'b1;
    8'h31:            fnSource2_v = 1'b1;
    8'h32:            fnSource2_v = 1'b1;
    8'h33:            fnSource2_v = 1'b1;
    8'h34:            fnSource2_v = 1'b1;
    8'h35:            fnSource2_v = 1'b1;
    8'h36:            fnSource2_v = 1'b1;
    8'h37:            fnSource2_v = 1'b1;
    8'h38:            fnSource2_v = 1'b1;
    8'h39:            fnSource2_v = 1'b1;
    8'h3A:            fnSource2_v = 1'b1;
    8'h3B:            fnSource2_v = 1'b1;
    8'h3C:            fnSource2_v = 1'b1;
    8'h3D:            fnSource2_v = 1'b1;
    8'h3E:            fnSource2_v = 1'b1;
    8'h3F:            fnSource2_v = 1'b1;
        `MULI,`MULUI,`DIVI,`DIVUI,`MODI,`MODUI:
                                        fnSource2_v = 1'b1;
        `ANDI,`BITI:    fnSource2_v = 1'b1;
        `ORI:                   fnSource2_v = 1'b1;
        `EORI:                  fnSource2_v = 1'b1;
        `SHIFT:
                   if (func>=6'h10)
                       fnSource2_v = `TRUE;
                   else
                       fnSource2_v = `FALSE;
        `CACHE,`LCL,`TLB,`LLA,
        `LVB,`LVC,`LVH,`LVW,`LVWAR,
        `LB,`LBU,`LC,`LCU,`LH,`LHU,`LW,`LWS,`STI,`INC:
                        fnSource2_v = 1'b1;
        `JSR,`JSRS,`JSRZ,`SYS,`INT,`RTS,`RTS2:
                        fnSource2_v = 1'b1;
        `MTSPR,`MFSPR,`POP,`UNLINK:
                                fnSource2_v = 1'b1;
        `BITFIELD:
               if (func==`BFINS)
                   fnSource2_v = 1'b0;
               else
                   fnSource2_v = 1'b1;
        `LOOP:      fnSource2_v = 1'b1;
        default:    fnSource2_v = 1'b0;
        endcase
endfunction
 
 
// Source #3 valid
// Since most instructions don't use a third source the default it to return 
// a valid status.
// 1 if the the operand is automatically valid, 
// 0 if we need a RF value
function fnSource3_v;
input [7:0] opcode;
input [5:0] func;
        case(opcode)
        `RR:
           case(func)
           `CHK:   fnSource3_v = 1'b0;
           default:    fnSource3_v = 1'b1;
           endcase
        `SBX,`SCX,`SHX,`SWX,`CAS,`STMV,`STCMP,`STFND:   fnSource3_v = 1'b0;
        `MUX:   fnSource3_v = 1'b0;
        default:        fnSource3_v = 1'b1;
        endcase
endfunction
 
function fnSourceT_v;
input [7:0] opcode;
input [5:0] func;
    case(opcode)
    `RR:
        case(func)
        `CHK:   fnSourceT_v = 1'b1;
        default:    fnSourceT_v = 1'b0;
        endcase
    // BR
    8'h30,8'h31,8'h32,8'h33,
    8'h34,8'h35,8'h36,8'h37,
    8'h38,8'h39,8'h3A,8'h3B,
    8'h3C,8'h3D,8'h3E,8'h3F,
    `SB,`SC,`SH,`SW,`SBX,`SCX,`SHX,`SWX,`SWS,
    `CACHE,`CHKI,
    `SEI,`CLI,`NOP,`STP,`RTI,`RTD,`RTE,
    `MEMSB,`MEMDB,`SYNC:
            fnSourceT_v = 1'b1;
    default:    fnSourceT_v = 1'b0;
    endcase
endfunction
 
// Return the number of register read ports required for an instruction.
function [2:0] fnNumReadPorts;
input [63:0] ins;
case(fnOpcode(ins))
`SEI,`CLI,`MEMSB,`MEMDB,`SYNC,`NOP,`MOVS,`STP:
                                        fnNumReadPorts = 3'd0;
`LDI,`LDIS,`IMM:                fnNumReadPorts = 3'd0;
`R,`P,`STI,`LOOP,`JMPI:   fnNumReadPorts = 3'd1;
`RTI,`RTD,`RTE:         fnNumReadPorts = 3'd1;
`ADDI,`ADDUI,`ADDUIS:
                    fnNumReadPorts = 3'd1;
`_2ADDUI,`_4ADDUI,`_8ADDUI,`_16ADDUI:
                                        fnNumReadPorts = 3'd1;
`SUBI,`SUBUI:           fnNumReadPorts = 3'd1;
`MULI,`MULUI,`DIVI,`DIVUI,`MODI,`MODUI:
                                        fnNumReadPorts = 3'd1;
`BITI,
`ANDI,`ORI,`EORI:       fnNumReadPorts = 3'd1;
`SHIFT:
                    if (ins[39:38]==2'h1)   // shift immediate
                                           fnNumReadPorts = 3'd1;
                                        else
                                           fnNumReadPorts = 3'd2;
`CACHE,`LCL,`TLB,`LLA,
`LB,`LBU,`LC,`LCU,`LH,`LHU,`LW,`LVB,`LVC,`LVH,`LVW,`LVWAR,`LWS,`INC:
                                        fnNumReadPorts = 3'd1;
`JSR,`JSRS,`JSRZ,`SYS,`INT,`RTS,`RTS2,`BR:
                                        fnNumReadPorts = 3'd1;
`SBX,`SCX,`SHX,`SWX,
`MUX,`CAS,`STMV,`STCMP:
                                        fnNumReadPorts = 3'd3;
`MTSPR,`MFSPR,`POP,`UNLINK:     fnNumReadPorts = 3'd1;
`STFND:    fnNumReadPorts = 3'd2;       // *** TLB reads on Rb we say 2 for simplicity
`RR:
    case(ins[39:34])
    `CHK:   fnNumReadPorts = 3'd3;
    default:    fnNumReadPorts = 3'd2;
    endcase
`BITFIELD:
    case(ins[43:40])
    `BFSET,`BFCLR,`BFCHG,`BFEXT,`BFEXTU,`BFINSI:
                                        fnNumReadPorts = 3'd1;
    `BFINS:         fnNumReadPorts = 3'd2;
    default:        fnNumReadPorts = 3'd0;
    endcase
default:
    case(ins[15:12])
    `TST:                       fnNumReadPorts = 3'd1;
    `CMPI:                      fnNumReadPorts = 3'd1;
    `CMP:                       fnNumReadPorts = 3'd2;
    `BR:            fnNumReadPorts = 3'd0;
    default:        fnNumReadPorts = 3'd2;
    endcase
endcase
endfunction
 
function fnIsBranch;
input [7:0] opcode;
case(opcode[7:4])
`BR:    fnIsBranch = `TRUE;
default:        fnIsBranch = `FALSE;
endcase
endfunction
 
function fnIsPush;
input [63:0] isn;
fnIsPush = isn[15:8]==`PUSH || isn[15:8]==`PEA;
endfunction
 
function fnIsPop;
input [63:0] isn;
fnIsPop = isn[15:8]==`POP;
endfunction
 
function fnIsStoreString;
input [7:0] opcode;
fnIsStoreString =
        opcode==`STS;
endfunction
 
reg [DBW-1:0] branch_pc;
wire xbr = iqentry_br[head0] | iqentry_br[head1];
wire takb = iqentry_br[head0] ? commit0_v : commit1_v;
wire [DBW-1:0] xbrpc = iqentry_br[head0] ? iqentry_pc[head0] : iqentry_pc[head1];
 
wire predict_taken0;
wire predict_taken1;
 
// This is really just a single history table with three read ports.
// One for fetchbuf0, one for fetchbuf1 and one for the branch_pc.
// Ideally, there really needs to be two write ports as well (for
// head0 and head1).
// There is only a single write port for branches committing at
// head0 or head1. If there are two branches one after the other
// in code, then the prediction will be off because the taken/
// not taken status for the second branch won't be updated. It
// doesn't happen that often that branches are piled together and
// executing during the same clock cycle.
// There's usually at least an intervening compare operation.
// Needs more work yet.
//
// ToDo: add return address stack predictor.
//
Thor_BranchHistory #(DBW) ubhtA
(
        .rst(rst_i),
        .clk(clk),
        .advanceX(xbr),
        .xisBranch(xbr),
        .pc(branch_pc),
        .xpc(xbrpc),
        .takb(takb),
        .predict_taken(predict_takenBr)
);
 
Thor_BranchHistory #(DBW) ubhtB
(
        .rst(rst_i),
        .clk(clk),
        .advanceX(xbr),
        .xisBranch(xbr),
        .pc(fetchbuf0_pc),
        .xpc(xbrpc),
        .takb(takb),
        .predict_taken(predict_taken0)
);
 
Thor_BranchHistory #(DBW) ubhtC
(
        .rst(rst_i),
        .clk(clk),
        .advanceX(xbr),
        .xisBranch(xbr),
        .pc(fetchbuf1_pc),
        .xpc(xbrpc),
        .takb(takb),
        .predict_taken(predict_taken1)
);
 
/*
Thor_BranchHistory #(DBW) ubhtC
(
        .rst(rst_i),
        .clk(clk),
        .advanceX(xbr),
        .xisBranch(xbr),
        .pc(pc),
        .xpc(xbrpc),
        .takb(takb),
        .predict_taken(predict_takenC)
);
 
Thor_BranchHistory #(DBW) ubhtD
(
        .rst(rst_i),
        .clk(clk),
        .advanceX(xbr),
        .xisBranch(xbr),
        .pc(pc+fnInsnLength(insn)),
        .xpc(xbrpc),
        .takb(takb),
        .predict_taken(predict_takenD)
);
*/
`ifdef PCHIST
wire [63:0] pc_histo;
reg pc_cap;
reg [5:0] pc_ndx;
vtdl #(.WID(64),.DEP(64)) uvtl1
(
    .clk(clk),
    .ce(pc_cap),
    .a(pc_ndx),
    .d({fetchbuf1_pc,fetcbuf0_pc}),
    .q(pc_histo)
);
`endif
 
Thor_icachemem #(.DBW(DBW),.ABW(ABW),.ECC(1'b0)) uicm1
(
        .wclk(clk),
        .wce(cstate==ICACHE1),
        .wr(ack_i|err_i),
        .wa(adr_o),
        .wd(dat_i),
        .rclk(~clk),
        .pc(ppc),
        .insn(insn)
);
 
wire hit0,hit1;
reg ic_ld;
reg [31:0] ic_ld_cntr;
Thor_itagmem #(DBW-1) uitm1
(
        .wclk(clk),
        .wce((cstate==ICACHE1 && cti_o==3'b111)|ic_ld),
        .wr(ack_i|err_i|ic_ld),
        .wa(adr_o|ic_ld_cntr),
        .err_i(err_i|ierr),
        .invalidate(ic_invalidate),
        .invalidate_line(ic_invalidate_line),
        .invalidate_lineno(ic_lineno),
        .rclk(~clk),
        .rce(1'b1),
        .pc(ppc),
        .hit0(hit0),
        .hit1(hit1),
        .err_o(insnerr)
);
 
wire ihit = hit0 & hit1;
wire do_pcinc = ihit;// && !((nmi_edge & ~StatusHWI & ~int_commit) || (irq_i & ~im & ~StatusHWI & ~int_commit));
wire ld_fetchbuf = ihit || (nmi_edge & !StatusHWI)||(irq_i & ~im & !StatusHWI);
 
wire whit;
 
Thor_dcachemem_1w1r #(DBW) udcm1
(
        .wclk(clk),
        .wce(whit || cstate==DCACHE1),
        .wr(ack_i|err_i),
        .sel(whit ? sel_o : 8'hFF),
        .wa(adr_o),
        .wd(whit ? dat_o : dat_i[DBW-1:0]),
        .rclk(~clk),
        .rce(1'b1),
        .ra(pea),
        .o(cdat)
);
 
Thor_dtagmem #(DBW-1) udtm1
(
        .wclk(clk),
        .wce(cstate==DCACHE1 && cti_o==3'b111),
        .wr(ack_i|err_i),
        .wa(adr_o),
        .err_i(err_i|derr),
        .invalidate(dc_invalidate),
        .invalidate_line(dc_invalidate_line),
    .invalidate_lineno(dc_lineno),
        .rclk(~clk),
        .rce(1'b1),
        .ra(pea),
        .whit(whit),
        .rhit(rhit),
        .err_o()
);
 
wire [DBW-1:0] shfto0,shfto1;
 
function fnIsShiftiop;
input [63:0] isn;
fnIsShiftiop =  isn[15:8]==`SHIFT && (
                isn[39:34]==`SHLI || isn[39:34]==`SHLUI ||
                                isn[39:34]==`SHRI || isn[39:34]==`SHRUI ||
                                isn[39:34]==`ROLI || isn[39:34]==`RORI
                                )
                                ;
endfunction
 
function fnIsShiftop;
input [7:0] opcode;
fnIsShiftop = opcode==`SHL || opcode==`SHLI || opcode==`SHLU || opcode==`SHLUI ||
                                opcode==`SHR || opcode==`SHRI || opcode==`SHRU || opcode==`SHRUI ||
                                opcode==`ROL || opcode==`ROLI || opcode==`ROR || opcode==`RORI
                                ;
endfunction
 
function fnIsFP;
input [7:0] opcode;
fnIsFP =        opcode==`DOUBLE_R||opcode==`FLOAT||opcode==`SINGLE_R;
//            opcode==`ITOF || opcode==`FTOI || opcode==`FNEG || opcode==`FSIGN || /*opcode==`FCMP || */ opcode==`FABS ||
//                      opcode==`FADD || opcode==`FSUB || opcode==`FMUL || opcode==`FDIV
//                      ;
endfunction
 
function fnIsFPCtrl;
input [63:0] isn;
fnIsFPCtrl = (isn[15:8]==`SINGLE_R && (isn[31:28]==`FTX||isn[31:28]==`FCX||isn[31:28]==`FDX||isn[31:28]==`FEX)) ||
             (isn[15:8]==`DOUBLE_R && (isn[31:28]==`FRM))
             ;
endfunction
 
function fnIsBitfield;
input [7:0] opcode;
fnIsBitfield = opcode==`BITFIELD;
endfunction
 
//wire [3:0] Pn = ir[7:4];
 
// Set the target register
// 00-3F = general register file
// 40-4F = predicate register
// 50-5F = code address register
// 60-67 = segment base register
// 68-6F = segment limit register
// 70 = predicate register horizontal
// 73 = loop counter
// 7C = breakout index register
// 7D = broken out register
// 7F = power shift register
function [6:0] fnTargetReg;
input [63:0] ir;
begin
    // Process special predicates (NOP, IMM)
    // Note that BRK (00) is already translated to a SYS instruction
        if (ir[3:0]==4'h0)
                fnTargetReg = 7'h000;
        else
                case(fnOpcode(ir))
                `POP: fnTargetReg = ir[22:16];
                `LDI,`ADDUIS,`STS,`LINK,`UNLINK:
                    if (ir[21:16]==6'd27)
                        fnTargetReg = r27;
                    else
                            fnTargetReg = {1'b0,ir[21:16]};
                `LDIS:
                        fnTargetReg = {1'b1,ir[21:16]};
                `RR,
                `SHIFT,
                `BCD,
        `LOGIC,`FLOAT,
        `LWX,`LBX,`LBUX,`LCX,`LCUX,`LHX,`LHUX,`STMV,`STCMP,`STFND:
                    if (ir[33:28]==6'd27)
                        fnTargetReg = r27;
                    else
                            fnTargetReg = {1'b0,ir[33:28]};
                `R,`R2,`DOUBLE_R,`SINGLE_R,
                `ADDI,`ADDUI,`SUBI,`SUBUI,
                `MULI,`MULUI,`DIVI,`DIVUI,`MODI,`MODUI,
                `_2ADDUI,`_4ADDUI,`_8ADDUI,`_16ADDUI,
                `ANDI,`ORI,`EORI,`LLA,
                `LVB,`LVC,`LVH,`LVW,`LVWAR,
                `LB,`LBU,`LC,`LCU,`LH,`LHU,`LW,`LINK,
                `BITFIELD,`MFSPR:
                    if (ir[27:22]==6'd27)
                        fnTargetReg = r27;
                    else
                            fnTargetReg = {1'b0,ir[27:22]};
                `CAS:
                        fnTargetReg = {1'b0,ir[39:34]};
                `TLB:
                        if (ir[19:16]==`TLB_RDREG)
                                fnTargetReg = {1'b0,ir[29:24]};
                        else
                                fnTargetReg = 7'h00;
                `BITI:
                      fnTargetReg = {3'h4,ir[25:22]};
                // TST
                8'h00,8'h01,8'h02,8'h03,
                8'h04,8'h05,8'h06,8'h07,
                8'h08,8'h09,8'h0A,8'h0B,
                8'h0C,8'h0D,8'h0E,8'h0F,
                // CMP
                8'h10,8'h11,8'h12,8'h13,
        8'h14,8'h15,8'h16,8'h17,
        8'h18,8'h19,8'h1A,8'h1B,
        8'h1C,8'h1D,8'h1E,8'h1F,
                // CMPI
        8'h20,8'h21,8'h22,8'h23,
        8'h24,8'h25,8'h26,8'h27,
        8'h28,8'h29,8'h2A,8'h2B,
        8'h2C,8'h2D,8'h2E,8'h2F:
                    begin
                        fnTargetReg = {3'h4,ir[11:8]};
                        end
                `SWCR:    fnTargetReg = {3'h4,4'h0};
                `JSR,`JSRZ,`JSRS,`SYS,`INT:
                        fnTargetReg = {3'h5,ir[19:16]};
                `JMPI:
                    fnTargetReg = {3'h5,ir[25:22]};
                `JMPIX:
                    fnTargetReg = {3'h5,ir[31:28]};
                `MTSPR,`MOVS,`LWS:
                    if (ir[27:22]==`USP)
                        fnTargetReg = {1'b0,6'd27};
                    else
                        fnTargetReg = {1'b1,ir[27:22]};
/*
                        if (ir[27:26]==2'h1)            // Move to code address register
                                fnTargetReg = {3'h5,ir[25:22]};
                        else if (ir[27:26]==2'h2)       // Move to seg. reg.
                                fnTargetReg = {3'h6,ir[25:22]};
                        else if (ir[27:22]==6'h04)
                                fnTargetReg = 7'h70;
                        else
                                fnTargetReg = 7'h00;
*/
        `PUSH:      fnTargetReg = r27;
        `LOOP:      fnTargetReg = 7'h73;
        `STP:       fnTargetReg = 7'h7F;
        `P:         fnTargetReg = 7'h70;
                default:        fnTargetReg = 7'h00;
                endcase
end
endfunction
/*
function fnAllowedReg;
input [8:0] regno;
fnAllowedReg = allowedRegs[regno] ? regno : 9'h000;
endfunction
*/
function fnTargetsCa;
input [63:0] ir;
begin
if (ir[3:0]==4'h0)
        fnTargetsCa = `FALSE;
else begin
        case(fnOpcode(ir))
        `JSR,`JSRZ,`JSRS,`SYS,`INT:
               fnTargetsCa = `TRUE;
        `JMPI,`JMPIX:
               fnTargetsCa = `TRUE;
        `LWS:
                if (ir[27:26]==2'h1)
                        fnTargetsCa = `TRUE;
                else
                        fnTargetsCa = `FALSE;
        `LDIS:
                if (ir[21:20]==2'h1)
                        fnTargetsCa = `TRUE;
                else
                        fnTargetsCa = `FALSE;
        `MTSPR,`MOVS:
                begin
                        if (ir[27:26]==2'h1)
                                fnTargetsCa = `TRUE;
                        else
                                fnTargetsCa = `FALSE;
                end
        default:        fnTargetsCa = `FALSE;
        endcase
end
end
endfunction
 
function fnTargetsSegreg;
input [63:0] ir;
if (ir[3:0]==4'h0)
        fnTargetsSegreg = `FALSE;
else
        case(fnOpcode(ir))
        `LWS:
                if (ir[27:26]==2'h2)
                        fnTargetsSegreg = `TRUE;
                else
                        fnTargetsSegreg = `FALSE;
        `LDIS:
                if (ir[21:20]==2'h2)
                        fnTargetsSegreg = `TRUE;
                else
                        fnTargetsSegreg = `FALSE;
        `MTSPR,`MOVS:
                if (ir[27:26]==2'h2)
                        fnTargetsSegreg = `TRUE;
                else
                        fnTargetsSegreg = `FALSE;
        default:        fnTargetsSegreg = `FALSE;
        endcase
endfunction
 
function fnHasConst;
input [7:0] opcode;
        case(opcode)
        `BFCLR,`BFSET,`BFCHG,`BFEXT,`BFEXTU,`BFINS,
        `LDI,`LDIS,`ADDUIS,
        `ADDI,`SUBI,`ADDUI,`SUBUI,`MULI,`MULUI,`DIVI,`DIVUI,`MODI,`MODUI,
        `_2ADDUI,`_4ADDUI,`_8ADDUI,`_16ADDUI,`CHKI,
        // CMPI
        8'h20,8'h21,8'h22,8'h23,
        8'h24,8'h25,8'h26,8'h27,
        8'h28,8'h29,8'h2A,8'h2B,
        8'h2C,8'h2D,8'h2E,8'h2F,
        // BR
    8'h30,8'h31,8'h32,8'h33,
    8'h34,8'h35,8'h36,8'h37,
    8'h38,8'h39,8'h3A,8'h3B,
    8'h3C,8'h3D,8'h3E,8'h3F,
        `ANDI,`ORI,`EORI,`BITI,
//      `SHLI,`SHLUI,`SHRI,`SHRUI,`ROLI,`RORI,
        `LB,`LBU,`LC,`LCU,`LH,`LHU,`LW,`LWS,`INC,
        `LVB,`LVC,`LVH,`LVW,`LVWAR,`STI,`JMPI,
        `SB,`SC,`SH,`SW,`SWCR,`CAS,`SWS,
        `RTI,`RTD,`RTE,`LLA,
        `JSR,`JSRS,`SYS,`INT,`LOOP,`PEA,`LINK,`UNLINK:
                fnHasConst = 1'b1;
        default:
                fnHasConst = 1'b0;
        endcase
endfunction
 
// Used by memory issue logic.
function fnIsFlowCtrl;
input [7:0] opcode;
begin
case(opcode)
`JMPI,`JMPIX,
`JSR,`JSRS,`JSRZ,`SYS,`INT,`LOOP,`RTS,`RTS2,`RTI,`RTD,`RTE:
        fnIsFlowCtrl = 1'b1;
default:
    if (opcode[7:4]==`BR)
        fnIsFlowCtrl = 1'b1;
    else
        fnIsFlowCtrl = 1'b0;
endcase
end
endfunction
 
// fnCanException
//
// Used by memory issue logic.
// Returns TRUE if the instruction can cause an exception.
// In debug mode any instruction could potentially cause a breakpoint exception.
// Rather than check all the addresses for potential debug exceptions it's
// simpler to just have it so that all instructions could exception. This will
// slow processing down somewhat as stores will only be done at the head of the
// instruction queue, but it's debug mode so we probably don't care.
//
function fnCanException;
input [7:0] op;
input [5:0] func;
if (debug_on)
    fnCanException = `TRUE;
else
case(op)
`FLOAT:
    case(func)
    `FDIVS,`FMULS,`FADDS,`FSUBS,
    `FDIV,`FMUL,`FADD,`FSUB:
        fnCanException = `TRUE;
    default:    fnCanException = `FALSE;
    endcase
`SINGLE_R:
    if (func==`FTX) fnCanException = `TRUE;
    else fnCanException = `FALSE;
`ADDI,`SUBI,`DIVI,`MODI,`MULI,`CHKI:
    fnCanException = `TRUE;
`RR:
    if (func==`ADD || func==`SUB || func==`MUL || func==`DIV || func==`MOD || func==`CHK)
        fnCanException = `TRUE;
    else
        fnCanException = `FALSE;
`TLB,`RTI,`RTD,`RTE,`CLI,`SEI:
    fnCanException = `TRUE;
default:
    fnCanException = fnIsMem(op);
endcase
endfunction
 
// fnInsnLength
// Used by fetch logic.
// Return the length of an instruction.
//
function [3:0] fnInsnLength;
input [127:0] isn;
case(isn[7:0])
8'b00000000:    fnInsnLength = 4'd1;    // BRK
8'b00010000:    fnInsnLength = 4'd1;    // NOP
8'b00100000:    fnInsnLength = 4'd2;
8'b00110000:    fnInsnLength = 4'd3;
8'b01000000:    fnInsnLength = 4'd4;
8'b01010000:    fnInsnLength = 4'd5;
8'b01100000:    fnInsnLength = 4'd6;
8'b01110000:    fnInsnLength = 4'd7;
8'b10000000:    fnInsnLength = 4'd8;
default:
        case(isn[15:8])
        `NOP,`SEI,`CLI,`RTI,`RTD,`RTE,`RTS2,`MEMSB,`MEMDB,`SYNC:
                fnInsnLength = 4'd2;
        `JSRZ,`RTS,`CACHE,`LOOP,`PUSH,`POP,`UNLINK:
                fnInsnLength = 4'd3;
        `SYS,`MTSPR,`MFSPR,`LDI,`LDIS,`ADDUIS,`R,`TLB,`MOVS,`STP:
                fnInsnLength = 4'd4;
        `BITFIELD,`JSR,`MUX,`BCD,`INC:
                fnInsnLength = 4'd6;
        `CAS:
                fnInsnLength = 4'd6;
        default:
           begin
            case(isn[15:12])
            `TST:     fnInsnLength = 4'd3;
            `BR:      fnInsnLength = 4'd3;
            `CMP,`CMPI:    fnInsnLength = 4'd4;
            default:       fnInsnLength = 4'd5;
            endcase
            end
        endcase
endcase
endfunction
 
function [3:0] fnInsnLength1;
input [127:0] isn;
case(fnInsnLength(isn))
4'd1:   fnInsnLength1 = fnInsnLength(isn[127: 8]);
4'd2:   fnInsnLength1 = fnInsnLength(isn[127:16]);
4'd3:   fnInsnLength1 = fnInsnLength(isn[127:24]);
4'd4:   fnInsnLength1 = fnInsnLength(isn[127:32]);
4'd5:   fnInsnLength1 = fnInsnLength(isn[127:40]);
4'd6:   fnInsnLength1 = fnInsnLength(isn[127:48]);
4'd7:   fnInsnLength1 = fnInsnLength(isn[127:56]);
4'd8:   fnInsnLength1 = fnInsnLength(isn[127:64]);
default:        fnInsnLength1 = 4'd0;
endcase
endfunction
 
function [3:0] fnInsnLength2;
input [127:0] isn;
case(fnInsnLength(isn)+fnInsnLength1(isn))
4'd2:   fnInsnLength2 = fnInsnLength(isn[127:16]);
4'd3:   fnInsnLength2 = fnInsnLength(isn[127:24]);
4'd4:   fnInsnLength2 = fnInsnLength(isn[127:32]);
4'd5:   fnInsnLength2 = fnInsnLength(isn[127:40]);
4'd6:   fnInsnLength2 = fnInsnLength(isn[127:48]);
4'd7:   fnInsnLength2 = fnInsnLength(isn[127:56]);
4'd8:   fnInsnLength2 = fnInsnLength(isn[127:64]);
4'd9:   fnInsnLength2 = fnInsnLength(isn[127:72]);
4'd10:  fnInsnLength2 = fnInsnLength(isn[127:80]);
4'd11:  fnInsnLength2 = fnInsnLength(isn[127:88]);
4'd12:  fnInsnLength2 = fnInsnLength(isn[127:96]);
4'd13:  fnInsnLength2 = fnInsnLength(isn[127:104]);
4'd14:  fnInsnLength2 = fnInsnLength(isn[127:112]);
4'd15:  fnInsnLength2 = fnInsnLength(isn[127:120]);
default:        fnInsnLength2 = 4'd0;
endcase
endfunction
 
wire [5:0] total_insn_length = fnInsnLength(insn) + fnInsnLength1(insn) + fnInsnLength2(insn);
wire [5:0] insn_length12 = fnInsnLength(insn) + fnInsnLength1(insn);
wire insn3_will_fit = total_insn_length < 6'd16;
 
always @(fetchbuf or fetchbufA_instr or fetchbufA_v or fetchbufA_pc
 or fetchbufB_instr or fetchbufB_v or fetchbufB_pc
 or fetchbufC_instr or fetchbufC_v or fetchbufC_pc
 or fetchbufD_instr or fetchbufD_v or fetchbufD_pc
)
begin
        fetchbuf0_instr <= (fetchbuf == 1'b0) ? fetchbufA_instr : fetchbufC_instr;
        fetchbuf0_v     <= (fetchbuf == 1'b0) ? fetchbufA_v     : fetchbufC_v    ;
 
        if (int_pending && string_pc!=64'd0)
                fetchbuf0_pc <= string_pc;
        else
        fetchbuf0_pc    <= (fetchbuf == 1'b0) ? fetchbufA_pc    : fetchbufC_pc   ;
 
        fetchbuf1_instr <= (fetchbuf == 1'b0) ? fetchbufB_instr : fetchbufD_instr;
        fetchbuf1_v     <= (fetchbuf == 1'b0) ? fetchbufB_v     : fetchbufD_v    ;
 
        if (int_pending && string_pc != 64'd0)
                fetchbuf1_pc <= string_pc;
        else
        fetchbuf1_pc    <= (fetchbuf == 1'b0) ? fetchbufB_pc    : fetchbufD_pc   ;
end
 
wire [7:0] opcodeA = fnOpcode(fetchbufA_instr);
wire [7:0] opcodeB = fnOpcode(fetchbufB_instr);
wire [7:0] opcodeC = fnOpcode(fetchbufC_instr);
wire [7:0] opcodeD = fnOpcode(fetchbufD_instr);
 
function fnIsMem;
input [7:0] opcode;
fnIsMem =       opcode==`LB || opcode==`LBU || opcode==`LC || opcode==`LCU || opcode==`LH || opcode==`LHU || opcode==`LW ||
                        opcode==`LBX || opcode==`LWX || opcode==`LBUX || opcode==`LHX || opcode==`LHUX || opcode==`LCX || opcode==`LCUX ||
                        opcode==`SB || opcode==`SC || opcode==`SH || opcode==`SW ||
                        opcode==`SBX || opcode==`SCX || opcode==`SHX || opcode==`SWX ||
                        opcode==`STS || opcode==`LCL ||
                        opcode==`LVB || opcode==`LVC || opcode==`LVH || opcode==`LVW || opcode==`LVWAR || opcode==`SWCR ||
                        opcode==`TLB || opcode==`CAS || opcode==`STMV || opcode==`STCMP || opcode==`STFND ||
                        opcode==`LWS || opcode==`SWS || opcode==`STI ||
                        opcode==`INC ||
                        opcode==`JMPI || opcode==`JMPIX ||
                        opcode==`PUSH || opcode==`POP || opcode==`PEA || opcode==`LINK || opcode==`UNLINK
                        ;
endfunction
 
// Determines which instruction write to the register file
function fnIsRFW;
input [7:0] opcode;
input [63:0] ir;
begin
fnIsRFW =       // General registers
                        opcode==`LB || opcode==`LBU || opcode==`LC || opcode==`LCU || opcode==`LH || opcode==`LHU || opcode==`LW ||
                        opcode==`LBX || opcode==`LBUX || opcode==`LCX || opcode==`LCUX || opcode==`LHX || opcode==`LHUX || opcode==`LWX ||
                        opcode==`LVB || opcode==`LVH || opcode==`LVC || opcode==`LVW || opcode==`LVWAR || opcode==`SWCR ||
                        opcode==`STP || opcode==`LLA || opcode==`LLAX ||
                        opcode==`CAS || opcode==`LWS || opcode==`STMV || opcode==`STCMP || opcode==`STFND ||
                        opcode==`STS || opcode==`PUSH || opcode==`POP || opcode==`LINK || opcode==`UNLINK ||
                        opcode==`JMPI || opcode==`JMPIX ||
                        opcode==`ADDI || opcode==`SUBI || opcode==`ADDUI || opcode==`SUBUI ||
                        opcode==`MULI || opcode==`MULUI || opcode==`DIVI || opcode==`DIVUI || opcode==`MODI || opcode==`MODUI ||
                        opcode==`_2ADDUI || opcode==`_4ADDUI || opcode==`_8ADDUI || opcode==`_16ADDUI ||
                        opcode==`ANDI || opcode==`ORI || opcode==`EORI ||
                        opcode==`SHIFT || opcode==`LOGIC ||
                        opcode==`R || opcode==`R2 || opcode==`RR || opcode==`P || opcode==`LOOP ||
                        opcode==`BITI || opcode==`CMP || opcode==`CMPI || opcode==`TST ||
                        opcode==`LDI || opcode==`LDIS || opcode==`ADDUIS || opcode==`MFSPR ||
`ifdef FLOATING_POINT
                        opcode==`DOUBLE_R || opcode==`FLOAT_RR || opcode==`SINGLE_R ||
`endif
                        // Branch registers / Segment registers
                        ((opcode==`MTSPR || opcode==`MOVS) /*&& (fnTargetsCa(ir) || fnTargetsSegreg(ir))*/) ||
                        opcode==`JSR || opcode==`JSRS || opcode==`JSRZ || opcode==`SYS || opcode==`INT ||
                        // predicate registers
                        (opcode[7:4] < 4'h3) ||
                        (opcode==`TLB && ir[19:16]==`TLB_RDREG) ||
                        opcode==`BCD
                        ;
end
endfunction
 
function fnIsStore;
input [7:0] opcode;
fnIsStore =     opcode==`SB || opcode==`SC || opcode==`SH || opcode==`SW ||
                                opcode==`SBX || opcode==`SCX || opcode==`SHX || opcode==`SWX ||
                                opcode==`STS || opcode==`SWCR ||
                                opcode==`SWS || opcode==`STI ||
                                opcode==`PUSH || opcode==`PEA || opcode==`LINK;
endfunction
 
function fnIsLoad;
input [7:0] opcode;
fnIsLoad =      opcode==`LB || opcode==`LBU || opcode==`LC || opcode==`LCU || opcode==`LH || opcode==`LHU || opcode==`LW ||
                        opcode==`LBX || opcode==`LBUX || opcode==`LCX || opcode==`LCUX || opcode==`LHX || opcode==`LHUX || opcode==`LWX ||
                        opcode==`LVB || opcode==`LVC || opcode==`LVH || opcode==`LVW || opcode==`LVWAR || opcode==`LCL ||
                        opcode==`LWS || opcode==`UNLINK || opcode==`JMPI || opcode==`JMPIX ||
                        opcode==`POP;
endfunction
 
function fnIsLoadV;
input [7:0] opcode;
fnIsLoadV = opcode==`LVB || opcode==`LVC || opcode==`LVH || opcode==`LVW || opcode==`LVWAR || opcode==`LCL;
endfunction
 
function fnIsIndexed;
input [7:0] opcode;
fnIsIndexed = opcode==`LBX || opcode==`LBUX || opcode==`LCX || opcode==`LCUX || opcode==`LHX || opcode==`LHUX || opcode==`LWX ||
                                opcode==`SBX || opcode==`SCX || opcode==`SHX || opcode==`SWX || opcode==`JMPIX;
endfunction
 
// 
function fnIsPFW;
input [7:0] opcode;
fnIsPFW =       opcode[7:4]<4'h3 || opcode==`BITI || opcode==`P;//opcode==`CMP || opcode==`CMPI || opcode==`TST;
endfunction
 
// Decoding for illegal opcodes
function fnIsIllegal;
input [7:0] op;
input [5:0] fn;
casex(op)
8'h40:
    if (fn > 6'h17)
        fnIsIllegal = `TRUE;
    else if (fn==6'hC || fn==6'hD || fn==6'hE || fn==6'hF || fn==6'h12 || fn==6'h15 || fn==6'h16)
        fnIsIllegal = `TRUE;
    else fnIsIllegal = `FALSE;
8'h41:
    if (fn > 6'd3)  fnIsIllegal = `TRUE;
    else fnIsIllegal = `FALSE;
8'h42:
    if (fn > 6'd7)  fnIsIllegal = `TRUE;
    else fnIsIllegal = `FALSE;
8'h50:
    if (fn > 6'd7)  fnIsIllegal = `TRUE;
    else fnIsIllegal = `FALSE;
8'h58:
    if (fn > 6'h15 || (fn > 6'h5 && fn < 6'h10))
        fnIsIllegal = `TRUE;
    else
        fnIsIllegal = `FALSE;
8'h77:
    if (fn==8'h99 || fn==8'h9A || fn==8'h9B || fn==8'h9E || fn==8'h9F)
        fnIsIllegal = `TRUE;
    else
        fnIsIllegal = `FALSE;
8'h78:
    if ((fn >= 8'h07 && fn <= 8'h0B) || (fn >= 8'h17 && fn <= 8'h1B))
        fnIsIllegal = `FALSE;
    else
        fnIsIllegal = `TRUE;
8'h79:
    if (fn==8'h99 || fn==8'h9A || fn==8'h9B)
        fnIsIllegal = `TRUE;
    else
        fnIsIllegal = `FALSE;
8'hAA:
    if (fn > 4'd6)
        fnIsIllegal = `TRUE;
    else
        fnIsIllegal = `FALSE;
8'hF5:
    if (fn > 4'd2)
        fnIsIllegal = `TRUE;
    else
        fnIsIllegal = `FALSE;
8'h43,8'h44,8'h45:  fnIsIllegal = `TRUE;
8'h52,8'h56,8'h57,8'h59,8'h5A,8'h5C,8'h5E:
    fnIsIllegal = `TRUE;
8'h60,8'h61,8'h62,8'h63,8'h64,8'h65,8'h66,8'h67,8'h68,8'h69:
    fnIsIllegal = `TRUE;
8'h73,8'h74,8'h75,8'h76,8'h7A,8'h7B,8'h7C,8'h7D,8'h7E,8'h7F:
    fnIsIllegal = `TRUE;
8'h87,8'h88,8'h89,8'h8A:
    fnIsIllegal = `TRUE;
8'h94,8'h95,8'h9C:
    fnIsIllegal = `TRUE;
8'hB9,8'hBA,8'hBB,8'hBC,8'hBD,8'hBE,8'hBF:
    fnIsIllegal = `TRUE;
8'hC4,8'hC5,8'b11001xxx:
    fnIsIllegal = `TRUE;
8'hDx:  fnIsIllegal = `TRUE;
8'hEx:  fnIsIllegal = `TRUE;
8'hFD,8'hFE:    fnIsIllegal = `TRUE;
default:    fnIsIllegal = `FALSE;
endcase
endfunction
 
function [7:0] fnSelect;
input [7:0] opcode;
input [5:0] fn;
input [DBW-1:0] adr;
begin
if (DBW==32)
        case(opcode)
        `STS,`STMV,`STCMP,`STFND,`INC:
           case(fn[2:0])
           3'd0:
           case(adr[1:0])
           3'd0:    fnSelect = 8'h11;
           3'd1:    fnSelect = 8'h22;
           3'd2:    fnSelect = 8'h44;
           3'd3:    fnSelect = 8'h88;
           endcase
       3'd1:
                   case(adr[1])
           1'd0:    fnSelect = 8'h33;
           1'd1:    fnSelect = 8'hCC;
           endcase
       3'd2:
                fnSelect = 8'hFF;
       default: fnSelect = 8'h00;
       endcase
    `JMPI,`JMPIX:
        case(fn[1:0])
        2'd1:
            case(adr[1])
            1'b0:   fnSelect = 8'h33;
            1'b1:   fnSelect = 8'hCC;
            endcase
        2'd2:   fnSelect = 8'hFF;
        2'd3:   fnSelect = 8'hFF;
        default:    fnSelect = 8'h00;
        endcase
        `LB,`LBU,`LBX,`LBUX,`SB,`SBX,`LVB:
                case(adr[1:0])
                3'd0:   fnSelect = 8'h11;
                3'd1:   fnSelect = 8'h22;
                3'd2:   fnSelect = 8'h44;
                3'd3:   fnSelect = 8'h88;
                endcase
        `LC,`LCU,`SC,`LVC,`LCX,`LCUX,`SCX:
                case(adr[1])
                1'd0:   fnSelect = 8'h33;
                1'd1:   fnSelect = 8'hCC;
                endcase
        `LH,`LHU,`SH,`LVH,`LHX,`LHUX,`SHX:
                fnSelect = 8'hFF;
        `LW,`LWX,`SW,`SWCR,`LVW,`LVWAR,`SWX,`CAS,`LWS,`SWS,`STI,`LCL,
        `PUSH,`PEA,`POP,`LINK,`UNLINK:
                fnSelect = 8'hFF;
        default:        fnSelect = 8'h00;
        endcase
else
        case(opcode)
        `STS,`STMV,`STCMP,`STFND,`INC:
       case(fn[2:0])
       3'd0:
           case(adr[2:0])
           3'd0:    fnSelect = 8'h01;
           3'd1:    fnSelect = 8'h02;
           3'd2:    fnSelect = 8'h04;
           3'd3:    fnSelect = 8'h08;
           3'd4:    fnSelect = 8'h10;
           3'd5:    fnSelect = 8'h20;
           3'd6:    fnSelect = 8'h40;
           3'd7:    fnSelect = 8'h80;
           endcase
       3'd1:
           case(adr[2:1])
           2'd0:    fnSelect = 8'h03;
           2'd1:    fnSelect = 8'h0C;
           2'd2:    fnSelect = 8'h30;
           2'd3:    fnSelect = 8'hC0;
           endcase
       3'd2:
           case(adr[2])
           1'b0:    fnSelect = 8'h0F;
           1'b1:    fnSelect = 8'hF0;
           endcase
       3'd3:
           fnSelect = 8'hFF;
       default: fnSelect = 8'h00;
       endcase
    `JMPI,`JMPIX:
       case(fn[1:0])
       2'd1:
           case(adr[2:1])
           2'd0:   fnSelect = 8'h03;
           2'd1:   fnSelect = 8'h0C;
           2'd2:   fnSelect = 8'h30;
           2'd3:   fnSelect = 8'hC0;
           endcase
       2'd2:
            case(adr[2])
            1'b0:   fnSelect = 8'h0F;
            1'b1:   fnSelect = 8'hF0;
            endcase
       2'd3:   fnSelect = 8'hFF;
       default:    fnSelect = 8'h00;
       endcase
    `LB,`LBU,`LBX,`SB,`LVB,`LBUX,`SBX:
                case(adr[2:0])
                3'd0:   fnSelect = 8'h01;
                3'd1:   fnSelect = 8'h02;
                3'd2:   fnSelect = 8'h04;
                3'd3:   fnSelect = 8'h08;
                3'd4:   fnSelect = 8'h10;
                3'd5:   fnSelect = 8'h20;
                3'd6:   fnSelect = 8'h40;
                3'd7:   fnSelect = 8'h80;
                endcase
        `LC,`LCU,`SC,`LVC,`LCX,`LCUX,`SCX:
                case(adr[2:1])
                2'd0:   fnSelect = 8'h03;
                2'd1:   fnSelect = 8'h0C;
                2'd2:   fnSelect = 8'h30;
                2'd3:   fnSelect = 8'hC0;
                endcase
        `LH,`LHU,`SH,`LVH,`LHX,`LHUX,`SHX:
                case(adr[2])
                1'b0:   fnSelect = 8'h0F;
                1'b1:   fnSelect = 8'hF0;
                endcase
        `LW,`LWX,`SW,`SWCR,`LVW,`LVWAR,`SWX,`CAS,`LWS,`SWS,`STI,`LCL,
        `PUSH,`PEA,`POP,`LINK,`UNLINK:
                fnSelect = 8'hFF;
        default:        fnSelect = 8'h00;
        endcase
end
endfunction
 
function [DBW-1:0] fnDatai;
input [7:0] opcode;
input [5:0] func;
input [DBW-1:0] dat;
input [7:0] sel;
begin
if (DBW==32)
        case(opcode)
        `STMV,`STCMP,`STFND,`INC:
           case(func[2:0])
           3'd0,3'd4:
                case(sel[3:0])
        4'h1:    fnDatai = dat[7:0];
        4'h2:    fnDatai = dat[15:8];
        4'h4:    fnDatai = dat[23:16];
        4'h8:    fnDatai = dat[31:24];
        default:    fnDatai = {DBW{1'b1}};
        endcase
       3'd1,3'd5:
                case(sel[3:0])
        4'h3:    fnDatai = dat[15:0];
        4'hC:    fnDatai = dat[31:16];
        default:    fnDatai = {DBW{1'b1}};
        endcase
       default:
                fnDatai = dat[31:0];
           endcase
        `JMPI,`JMPIX:
           case(func[1:0])
           2'd1:
               case(sel[3:0])
               4'h3:   fnDatai = dat[15:0];
               4'hC:   fnDatai = dat[31:16];
               default:    fnDatai = {DBW{1'b1}};
               endcase
           2'd2:   fnDatai = dat[31:0];
           default:    fnDatai = dat[31:0];
           endcase
        `LB,`LBX,`LVB:
                case(sel[3:0])
                8'h1:   fnDatai = {{24{dat[7]}},dat[7:0]};
                8'h2:   fnDatai = {{24{dat[15]}},dat[15:8]};
                8'h4:   fnDatai = {{24{dat[23]}},dat[23:16]};
                8'h8:   fnDatai = {{24{dat[31]}},dat[31:24]};
                default:        fnDatai = {DBW{1'b1}};
                endcase
        `LBU,`LBUX:
                case(sel[3:0])
                4'h1:   fnDatai = dat[7:0];
                4'h2:   fnDatai = dat[15:8];
                4'h4:   fnDatai = dat[23:16];
                4'h8:   fnDatai = dat[31:24];
                default:        fnDatai = {DBW{1'b1}};
                endcase
        `LC,`LVC,`LCX:
                case(sel[3:0])
                4'h3:   fnDatai = {{16{dat[15]}},dat[15:0]};
                4'hC:   fnDatai = {{16{dat[31]}},dat[31:16]};
                default:        fnDatai = {DBW{1'b1}};
                endcase
        `LCU,`LCUX:
                case(sel[3:0])
                4'h3:   fnDatai = dat[15:0];
                4'hC:   fnDatai = dat[31:16];
                default:        fnDatai = {DBW{1'b1}};
                endcase
        `LH,`LHU,`LW,`LWX,`LVH,`LVW,`LVWAR,`LHX,`LHUX,`CAS,`LCL,`LWS,`POP,`UNLINK:
                fnDatai = dat[31:0];
        default:        fnDatai = {DBW{1'b1}};
        endcase
else
        case(opcode)
        `STMV,`STCMP,`STFND,`INC:
           case(func[2:0])
           3'd0,3'd4:
                case(sel)
        8'h01:    fnDatai = dat[DBW*1/8-1:0];
        8'h02:    fnDatai = dat[DBW*2/8-1:DBW*1/8];
        8'h04:    fnDatai = dat[DBW*3/8-1:DBW*2/8];
        8'h08:    fnDatai = dat[DBW*4/8-1:DBW*3/8];
        8'h10:    fnDatai = dat[DBW*5/8-1:DBW*4/8];
        8'h20:    fnDatai = dat[DBW*6/8-1:DBW*5/8];
        8'h40:    fnDatai = dat[DBW*7/8-1:DBW*6/8];
        8'h80:    fnDatai = dat[DBW-1:DBW*7/8];
        default:    fnDatai = {DBW{1'b1}};
        endcase
       3'd1,3'd5:
                case(sel)
        8'h03:    fnDatai = dat[DBW/4-1:0];
        8'h0C:    fnDatai = dat[DBW/2-1:DBW/4];
        8'h30:    fnDatai = dat[DBW*3/4-1:DBW/2];
        8'hC0:    fnDatai = dat[DBW-1:DBW*3/4];
        default:    fnDatai = {DBW{1'b1}};
        endcase
       3'd2,3'd6:
                case(sel)
        8'h0F:    fnDatai = dat[DBW/2-1:0];
        8'hF0:    fnDatai = dat[DBW-1:DBW/2];
        default:    fnDatai = {DBW{1'b1}};
        endcase
       3'd3,3'd7:   fnDatai = dat;
           endcase
        `JMPI,`JMPIX:
           case(func[1:0])
           2'd1:
               case(sel[7:0])
               8'h03:  fnDatai = dat[15:0];
               8'h0C:  fnDatai = dat[31:16];
               8'h30:  fnDatai = dat[47:32];
               8'hC0:  fnDatai = dat[63:48];
               default:    fnDatai = dat[15:0];
               endcase
           2'd2:
               case(sel[7:0])
           8'h0F:  fnDatai = dat[31:0];
           8'hF0:  fnDatai = dat[63:32];
           default: fnDatai = dat[31:0];
           endcase
       2'd3:    fnDatai = dat;
       default: fnDatai = dat;
           endcase
        `LB,`LBX,`LVB:
                case(sel)
                8'h01:  fnDatai = {{DBW*7/8{dat[DBW*1/8-1]}},dat[DBW*1/8-1:0]};
                8'h02:  fnDatai = {{DBW*7/8{dat[DBW*2/8-1]}},dat[DBW*2/8-1:DBW*1/8]};
                8'h04:  fnDatai = {{DBW*7/8{dat[DBW*3/8-1]}},dat[DBW*3/8-1:DBW*2/8]};
                8'h08:  fnDatai = {{DBW*7/8{dat[DBW*4/8-1]}},dat[DBW*4/8-1:DBW*3/8]};
                8'h10:  fnDatai = {{DBW*7/8{dat[DBW*5/8-1]}},dat[DBW*5/8-1:DBW*4/8]};
                8'h20:  fnDatai = {{DBW*7/8{dat[DBW*6/8-1]}},dat[DBW*6/8-1:DBW*5/8]};
                8'h40:  fnDatai = {{DBW*7/8{dat[DBW*7/8-1]}},dat[DBW*7/8-1:DBW*6/8]};
                8'h80:  fnDatai = {{DBW*7/8{dat[DBW-1]}},dat[DBW-1:DBW*7/8]};
                default:        fnDatai = {DBW{1'b1}};
                endcase
        `LBU,`LBUX:
                case(sel)
                8'h01:  fnDatai = dat[DBW*1/8-1:0];
                8'h02:  fnDatai = dat[DBW*2/8-1:DBW*1/8];
                8'h04:  fnDatai = dat[DBW*3/8-1:DBW*2/8];
                8'h08:  fnDatai = dat[DBW*4/8-1:DBW*3/8];
                8'h10:  fnDatai = dat[DBW*5/8-1:DBW*4/8];
                8'h20:  fnDatai = dat[DBW*6/8-1:DBW*5/8];
                8'h40:  fnDatai = dat[DBW*7/8-1:DBW*6/8];
                8'h80:  fnDatai = dat[DBW-1:DBW*7/8];
                default:        fnDatai = {DBW{1'b1}};
                endcase
        `LC,`LVC,`LCX:
                case(sel)
                8'h03:  fnDatai = {{DBW*3/4{dat[DBW/4-1]}},dat[DBW/4-1:0]};
                8'h0C:  fnDatai = {{DBW*3/4{dat[DBW/2-1]}},dat[DBW/2-1:DBW/4]};
                8'h30:  fnDatai = {{DBW*3/4{dat[DBW*3/4-1]}},dat[DBW*3/4-1:DBW/2]};
                8'hC0:  fnDatai = {{DBW*3/4{dat[DBW-1]}},dat[DBW-1:DBW*3/4]};
                default:        fnDatai = {DBW{1'b1}};
                endcase
        `LCU,`LCUX:
                case(sel)
                8'h03:  fnDatai = dat[DBW/4-1:0];
                8'h0C:  fnDatai = dat[DBW/2-1:DBW/4];
                8'h30:  fnDatai = dat[DBW*3/4-1:DBW/2];
                8'hC0:  fnDatai = dat[DBW-1:DBW*3/4];
                default:        fnDatai = {DBW{1'b1}};
                endcase
        `LH,`LVH,`LHX:
                case(sel)
                8'h0F:  fnDatai = {{DBW/2{dat[DBW/2-1]}},dat[DBW/2-1:0]};
                8'hF0:  fnDatai = {{DBW/2{dat[DBW-1]}},dat[DBW-1:DBW/2]};
                default:        fnDatai = {DBW{1'b1}};
                endcase
        `LHU,`LHUX:
                case(sel)
                8'h0F:  fnDatai = dat[DBW/2-1:0];
                8'hF0:  fnDatai = dat[DBW-1:DBW/2];
                default:        fnDatai = {DBW{1'b1}};
                endcase
        `LW,`LWX,`LVW,`LVWAR,`CAS,`LCL,`LWS,`POP,`UNLINK:
                case(sel)
                8'hFF:  fnDatai = dat;
                default:        fnDatai = {DBW{1'b1}};
                endcase
        default:        fnDatai = {DBW{1'b1}};
        endcase
end
endfunction
 
function [DBW-1:0] fnDatao;
input [7:0] opcode;
input [5:0] func;
input [DBW-1:0] dat;
if (DBW==32)
        case(opcode)
        `STMV,`INC:
           case(func[2:0])
           3'd0,3'd4:  fnDatao = {4{dat[7:0]}};
           3'd1,3'd5:  fnDatao = {2{dat[15:8]}};
           default:    fnDatao = dat;
           endcase
        `SW,`SWCR,`SWX,`CAS,`SWS,`STI,
        `PUSH,`PEA,`LINK:       fnDatao = dat;
        `SH,`SHX:       fnDatao = dat;
        `SC,`SCX:       fnDatao = {2{dat[15:0]}};
        `SB,`SBX:       fnDatao = {4{dat[7:0]}};
        default:        fnDatao = dat;
        endcase
else
        case(opcode)
        `STMV,`INC:
           case(func[2:0])
           3'd0,3'd4:  fnDatao = {8{dat[DBW/8-1:0]}};
           3'd1,3'd5:  fnDatao = {4{dat[DBW/4-1:0]}};
           3'd2,3'd6:  fnDatao = {2{dat[DBW/2-1:0]}};
           3'd3,3'd7:  fnDatao = dat;
           endcase
        `SW,`SWCR,`SWX,`CAS,`SWS,`STI,
        `PUSH,`PEA,`LINK:       fnDatao = dat;
        `SH,`SHX:       fnDatao = {2{dat[DBW/2-1:0]}};
        `SC,`SCX:       fnDatao = {4{dat[DBW/4-1:0]}};
        `SB,`SBX:       fnDatao = {8{dat[DBW/8-1:0]}};
        default:        fnDatao = dat;
        endcase
endfunction
 
assign fetchbuf0_mem    = fnIsMem(opcode0);
assign fetchbuf0_jmp   = fnIsFlowCtrl(opcode0);
assign fetchbuf0_fp             = fnIsFP(opcode0);
assign fetchbuf0_rfw    = fnIsRFW(opcode0,fetchbuf0_instr);
assign fetchbuf0_pfw    = fnIsPFW(opcode0);
assign fetchbuf1_mem    = fnIsMem(opcode1);
assign fetchbuf1_jmp   = fnIsFlowCtrl(opcode1);
assign fetchbuf1_fp             = fnIsFP(opcode1);
assign fetchbuf1_rfw    = fnIsRFW(opcode1,fetchbuf1_instr);
assign fetchbuf1_pfw    = fnIsPFW(opcode1);
 
//
// set branchback and backpc values ... ignore branches in fetchbuf slots not ready for enqueue yet
//
assign take_branch0 = ({fetchbuf0_v, fnIsBranch(opcode0), predict_taken0}  == {`VAL, `TRUE, `TRUE}) ||
                      ({fetchbuf0_v, opcode0==`LOOP}  == {`VAL, `TRUE})
                        ;
assign take_branch1 = ({fetchbuf1_v, fnIsBranch(opcode1), predict_taken1}  == {`VAL, `TRUE, `TRUE}) ||
                      ({fetchbuf1_v, opcode1==`LOOP}  == {`VAL, `TRUE})
                        ;
assign take_branch = take_branch0 || take_branch1
        ;
 
always @*
if (fnIsBranch(opcode0) && fetchbuf0_v && predict_taken0) begin
    branch_pc <= fetchbuf0_pc + {{ABW-12{fetchbuf0_instr[11]}},fetchbuf0_instr[11:8],fetchbuf0_instr[23:16]} + 64'd3;
end
else if (opcode0==`LOOP && fetchbuf0_v) begin
    branch_pc <= fetchbuf0_pc + {{ABW-8{fetchbuf0_instr[23]}},fetchbuf0_instr[23:16]} + 64'd3;
end
else if (fnIsBranch(opcode1) && fetchbuf1_v && predict_taken1) begin
    branch_pc <= fetchbuf1_pc + {{ABW-12{fetchbuf1_instr[11]}},fetchbuf1_instr[11:8],fetchbuf1_instr[23:16]} + 64'd3;
end
else if (opcode1==`LOOP && fetchbuf1_v) begin
    branch_pc <= fetchbuf1_pc + {{ABW-8{fetchbuf1_instr[23]}},fetchbuf1_instr[23:16]} + 64'd3;
end
else begin
    branch_pc <= RSTPC;  // set to something to prevent a latch
end
 
assign int_pending = (nmi_edge & ~StatusHWI & ~int_commit) || (irq_i & ~im & ~StatusHWI & ~int_commit);
 
assign mem_stringmissx = ((dram0_op==`STS || dram0_op==`STFND) && int_pending && lc != 0 && !mem_stringmiss) ||
                        ((dram0_op==`STMV || dram0_op==`STCMP) && int_pending && lc != 0 && !mem_stringmiss && stmv_flag);
 
assign jmpi_miss = dram_v && (dram0_op==`JMPI || dram0_op==`JMPIX);
 
// "Stream" interrupt instructions into the instruction stream until an INT
// instruction commits. This avoids the problem of an INT instruction being
// stomped on by a previous branch instruction.
// Populate the instruction buffers with INT instructions for a hardware interrupt
// Also populate the instruction buffers with a call to the instruction error vector
// if an error occurred during instruction load time.
// Translate the BRK opcode to a syscall.
 
// There is a one cycle delay in setting the StatusHWI that allowed an extra INT
// instruction to sneek into the queue. This is NOPped out by the int_commit
// signal.
 
// On a cache miss the instruction buffers are loaded with NOPs this prevents
// the PC from being trashed by invalid branch instructions.
reg [63:0] insn1a,insn2a;
reg [63:0] insn0,insn1,insn2;
always @*
//if (int_commit)
//      insn0 <= {8{8'h10}};    // load with NOPs
//else
if (nmi_edge & ~StatusHWI & ~int_commit)
        insn0 <= {8'hFE,8'hCE,8'hA6,8'h01,8'hFE,8'hCE,8'hA6,8'h01};
else if (ITLBMiss)
        insn0 <= {8'hF9,8'hCE,8'hA6,8'h01,8'hF9,8'hCE,8'hA6,8'h01};
else if (insnerr)
        insn0 <= {8'hFC,8'hCE,8'hA6,8'h01,8'hFC,8'hCE,8'hA6,8'h01};
else if (irq_i & ~im & ~StatusHWI & ~int_commit)
        insn0 <= {vec_i,8'hCE,8'hA6,8'h01,vec_i,8'hCE,8'hA6,8'h01};
else if (ihit) begin
        if (insn[7:0]==8'h00)
                insn0 <= {8'h00,8'hCD,8'hA5,8'h01,8'h00,8'hCD,8'hA5,8'h01};
        else
        insn0 <= insn[63:0];
end
else
        insn0 <= {8{8'h10}};    // load with NOPs
 
 
always @*
//if (int_commit)
//      insn1 <= {8{8'h10}};    // load with NOPs
//else
if (nmi_edge & ~StatusHWI & ~int_commit)
        insn1 <= {8'hFE,8'hCE,8'hA6,8'h01,8'hFE,8'hCE,8'hA6,8'h01};
else if (ITLBMiss)
        insn1 <= {8'hF9,8'hCE,8'hA6,8'h01,8'hF9,8'hCE,8'hA6,8'h01};
else if (insnerr)
        insn1 <= {8'hFC,8'hCE,8'hA6,8'h01,8'hFC,8'hCE,8'hA6,8'h01};
else if (irq_i & ~im & ~StatusHWI & ~int_commit)
        insn1 <= {vec_i,8'hCE,8'hA6,8'h01,vec_i,8'hCE,8'hA6,8'h01};
else if (ihit) begin
        if (insn1a[7:0]==8'h00)
                insn1 <= {8'h00,8'hCD,8'hA5,8'h01,8'h00,8'hCD,8'hA5,8'h01};
        else
                insn1 <= insn1a;
end
else
        insn1 <= {8{8'h10}};    // load with NOPs
 
 
// Find the second instruction in the instruction line.
always @(insn)
        case(fnInsnLength(insn))
        4'd1:   insn1a <= insn[71: 8];
        4'd2:   insn1a <= insn[79:16];
        4'd3:   insn1a <= insn[87:24];
        4'd4:   insn1a <= insn[95:32];
        4'd5:   insn1a <= insn[103:40];
        4'd6:   insn1a <= insn[111:48];
        4'd7:   insn1a <= insn[119:56];
        4'd8:   insn1a <= insn[127:64];
        default:        insn1a <= {8{8'h10}};   // NOPs
        endcase
 
// Return the immediate field of an instruction
function [63:0] fnImm;
input [127:0] insn;
case(insn[15:8])
`P:     fnImm = insn[33:16];
`CAS:   fnImm = {{56{insn[47]}},insn[47:40]};
`BCD:   fnImm = insn[47:40];
`TLB:   fnImm = insn[23:16];
`LOOP:  fnImm = {{56{insn[23]}},insn[23:16]};
`STP:   fnImm = insn[31:16];
`JSR:   fnImm = {{40{insn[47]}},insn[47:24]};
`JSRS:  fnImm = {{48{insn[39]}},insn[39:24]};
`BITFIELD:      fnImm = insn[47:32];
`SYS,`INT:      fnImm = {insn[31:24],4'h0};
//`CMPI,
8'h20,8'h21,8'h22,8'h23,
8'h24,8'h25,8'h26,8'h27,
8'h28,8'h29,8'h2A,8'h2B,
8'h2C,8'h2D,8'h2E,8'h2F,
`LDI,`LDIS,`ADDUIS:
        fnImm = {{54{insn[31]}},insn[31:22]};
`RTS:   fnImm = insn[19:16];
`RTD,`RTE,`RTI,`RTS2,`JSRZ,`STMV,`STCMP,`STFND,`CACHE,`STS:     fnImm = 64'h0;
`STI:   fnImm = {{58{insn[33]}},insn[33:28]};
`PUSH:  fnImm = 64'hFFFFFFFFFFFFFFF8;   //-8
//`LINK:  fnImm = {insn[39:28],3'b000};
`JMPI,`LLA,
`LB,`LBU,`LC,`LCU,`LH,`LHU,`LW,`LVB,`LVC,`LVH,`LVW,`LVWAR,
`SB,`SC,`SH,`SW,`SWCR,`LWS,`SWS,`INC,`LCL,`PEA:
        fnImm = {{55{insn[36]}},insn[36:28]};
default:
        fnImm = {{52{insn[39]}},insn[39:28]};
endcase
 
endfunction
 
function [7:0] fnImm8;
input [127:0] insn;
case(insn[15:8])
`CAS:   fnImm8 = insn[47:40];
`BCD:   fnImm8 = insn[47:40];
`TLB:   fnImm8 = insn[23:16];
`LOOP:  fnImm8 = insn[23:16];
`STP:   fnImm8 = insn[23:16];
`JSR,`JSRS:     fnImm8 = insn[31:24];
`BITFIELD:      fnImm8 = insn[39:32];
`SYS,`INT:      fnImm8 = {insn[27:24],4'h0};
//`CMPI,
8'h20,8'h21,8'h22,8'h23,
8'h24,8'h25,8'h26,8'h27,
8'h28,8'h29,8'h2A,8'h2B,
8'h2C,8'h2D,8'h2E,8'h2F,
`LDI,`LDIS,`ADDUIS:     fnImm8 = insn[29:22];
`RTS:   fnImm8 = insn[19:16];
`RTD,`RTE,`RTI,`RTS2,`JSRZ,`STMV,`STCMP,`STFND,`CACHE,`STS:     fnImm8 = 8'h00;
`STI:   fnImm8 = insn[35:28];
`PUSH:  fnImm8 = 8'hF8;
`ifdef STACKOPS
`LINK:  fnImm8 = {insn[32:28],3'b000};
`endif
`JMPI,`LLA,
`LB,`LBU,`LC,`LCU,`LH,`LHU,`LW,`LVB,`LVC,`LVH,`LVW,`LVWAR,
`SB,`SC,`SH,`SW,`SWCR,`LWS,`SWS,`INC,`LCL,`PEA:
        fnImm8 = insn[35:28];
default:        fnImm8 = insn[35:28];
endcase
endfunction
 
// Return MSB of immediate value for instruction
function fnImmMSB;
input [127:0] insn;
case(insn[15:8])
`CAS:   fnImmMSB = insn[47];
`TLB,`BCD,`STP:
        fnImmMSB = 1'b0;                // TLB regno is unsigned
`LOOP:
        fnImmMSB = insn[23];
`JSR:
        fnImmMSB = insn[47];
`JSRS:
    fnImmMSB = insn[39];
//`CMPI,
8'h20,8'h21,8'h22,8'h23,
8'h24,8'h25,8'h26,8'h27,
8'h28,8'h29,8'h2A,8'h2B,
8'h2C,8'h2D,8'h2E,8'h2F,
`LDI,`LDIS,`ADDUIS:
        fnImmMSB = insn[31];
`SYS,`INT,`CACHE,`LINK:
        fnImmMSB = 1'b0;                // SYS,INT are unsigned
`RTS,`RTD,`RTE,`RTI,`JSRZ,`STMV,`STCMP,`STFND,`RTS2,`STS:
        fnImmMSB = 1'b0;                // RTS is unsigned
`PUSH:  fnImmMSB = 1'b1;
`LBX,`LBUX,`LCX,`LCUX,`LHX,`LHUX,`LWX,
`SBX,`SCX,`SHX,`SWX:
        fnImmMSB = insn[47];
`JMPI,`LLA,
`LB,`LBU,`LC,`LCU,`LH,`LHU,`LW,`LVB,`LVC,`LVH,`LVW,
`SB,`SC,`SH,`SW,`SWCR,`STI,`LWS,`SWS,`INC,`LCL,`PEA:
        fnImmMSB = insn[36];
default:
        fnImmMSB = insn[39];
endcase
 
endfunction
 
function [63:0] fnImmImm;
input [63:0] insn;
case(insn[7:4])
4'd2:   fnImmImm = {{48{insn[15]}},insn[15:8],8'h00};
4'd3:   fnImmImm = {{40{insn[23]}},insn[23:8],8'h00};
4'd4:   fnImmImm = {{32{insn[31]}},insn[31:8],8'h00};
4'd5:   fnImmImm = {{24{insn[39]}},insn[39:8],8'h00};
4'd6:   fnImmImm = {{16{insn[47]}},insn[47:8],8'h00};
4'd7:   fnImmImm = {{ 8{insn[55]}},insn[55:8],8'h00};
4'd8:   fnImmImm = {insn[63:8],8'h00};
default:        fnImmImm = 64'd0;
endcase
endfunction
 
 
// Used during enque
// Operand A is a little more work than B or C as it may read from special
// purpose registers.
function [63:0] fnOpa;
input [7:0] opcode;
input [6:0] Ra;
input [63:0] ins;
input [63:0] rfo;
input [63:0] epc;
begin
`ifdef BITFIELDOPS
    if (opcode==`BITFIELD && ins[43:40]==`BFINSI)
        fnOpa = ins[21:16];
    else
`endif
        if (Ra[6])
                fnOpa = fnSpr(Ra[5:0],epc);
        else
                fnOpa = rfo;
end
endfunction
 
function [DBW-1:0] fnOpb;
input [7:0] opcode;
input [6:0] Rb;
input [63:0] ins;
input [63:0] rfo;
input [63:0] epc;
begin
    fnOpb = fnIsShiftiop(ins) ? {{DBW-6{1'b0}},ins[`INSTRUCTION_RB]} :
            fnIsFPCtrl(ins) ? {{DBW-6{1'b0}},ins[`INSTRUCTION_RB]} :
            opcode==`INC ? {{56{ins[47]}},ins[47:40]} :
            opcode==`STI ? ins[27:22] :
            Rb[6] ? fnSpr(Rb[5:0],epc) :
            rfo;
end
endfunction
 
// Used during enque
function [63:0] fnOpt;
input [6:0] tgt;
input [63:0] rfo;
input [63:0] epc;
begin
    if (tgt[6])
        fnOpt = fnSpr(tgt[5:0],epc);
    else
        fnOpt = rfo;
end
endfunction
 
// Returns TRUE if instruction is only allowed in kernel mode.
function fnIsKMOnly;
input [7:0] op;
`ifdef PRIVCHKS
    fnIsKMOnly = op==`RTI || op==`RTE || op==`RTD || op==`TLB || op==`CLI || op==`SEI ||
                 op==`STP
                ;
`else
    fnIsKMOnly = `FALSE;
`endif
endfunction
 
function fnIsKMOnlyReg;
input [6:0] regx;
`ifdef PRIVCHKS
    fnIsKMOnlyReg = regx==7'd28 || regx==7'd29 || regx==7'd30 || regx==7'd31 ||
                    regx==7'h5B || regx==7'h5C || regx==7'h5D || regx==7'h5E
                    ;
`else
    fnIsKMOnlyReg = `FALSE;
`endif
endfunction
 
// Returns TRUE if the register is automatically valid.
function fnRegIsAutoValid;
input [6:0] regno;  // r0, c0, c15, tick
fnRegIsAutoValid = regno==7'h00 || regno==7'h50 || regno==7'h5F || regno==7'h72;
endfunction
 
function [15:0] fnRegstrGrp;
input [6:0] Rn;
if (!Rn[6]) begin
        fnRegstrGrp="GP";
end
else
        case(Rn[5:4])
        2'h0:   fnRegstrGrp="PR";
        2'h1:   fnRegstrGrp="CA";
        2'h2:   fnRegstrGrp="SG";
        2'h3:
               case(Rn[3:0])
               3'h0:   fnRegstrGrp="PA";
               3'h3:   fnRegstrGrp="LC";
               endcase
        endcase
 
endfunction
 
function [7:0] fnRegstr;
input [6:0] Rn;
begin
if (!Rn[6]) begin
        fnRegstr = Rn[5:0];
end
else
        fnRegstr = Rn[3:0];
end
endfunction
 
initial begin
        //
        // set up panic messages
        message[ `PANIC_NONE ]                  = "NONE            ";
        message[ `PANIC_FETCHBUFBEQ ]           = "FETCHBUFBEQ     ";
        message[ `PANIC_INVALIDISLOT ]          = "INVALIDISLOT    ";
        message[ `PANIC_IDENTICALDRAMS ]        = "IDENTICALDRAMS  ";
        message[ `PANIC_OVERRUN ]               = "OVERRUN         ";
        message[ `PANIC_HALTINSTRUCTION ]       = "HALTINSTRUCTION ";
        message[ `PANIC_INVALIDMEMOP ]          = "INVALIDMEMOP    ";
        message[ `PANIC_INVALIDFBSTATE ]        = "INVALIDFBSTATE  ";
        message[ `PANIC_INVALIDIQSTATE ]        = "INVALIDIQSTATE  ";
        message[ `PANIC_BRANCHBACK ]            = "BRANCHBACK      ";
        message[ `PANIC_MEMORYRACE ]            = "MEMORYRACE      ";
end
 
//`include "Thor_issue_combo.v"
/*
assign  iqentry_imm[0] = fnHasConst(iqentry_op[0]),
        iqentry_imm[1] = fnHasConst(iqentry_op[1]),
        iqentry_imm[2] = fnHasConst(iqentry_op[2]),
        iqentry_imm[3] = fnHasConst(iqentry_op[3]),
        iqentry_imm[4] = fnHasConst(iqentry_op[4]),
        iqentry_imm[5] = fnHasConst(iqentry_op[5]),
        iqentry_imm[6] = fnHasConst(iqentry_op[6]),
        iqentry_imm[7] = fnHasConst(iqentry_op[7]);
*/
//
// additional logic for ISSUE
//
// for the moment, we look at ALU-input buffers to allow back-to-back issue of 
// dependent instructions ... we do not, however, look ahead for DRAM requests 
// that will become valid in the next cycle.  instead, these have to propagate
// their results into the IQ entry directly, at which point it becomes issue-able
//
/*
always @*
for (n = 0; n < QENTRIES; n = n + 1)
    iq_cmt[n] <= fnPredicate(iqentry_pred[n], iqentry_cond[n]) ||
        (iqentry_cond[n] < 4'h2 && ({iqentry_pred[n],iqentry_cond[n]}!=8'h90));
*/
wire [QENTRIES-1:0] args_valid;
wire [QENTRIES-1:0] could_issue;
 
genvar g;
generate
begin : argsv
 
for (g = 0; g < QENTRIES; g = g + 1)
begin
assign  iqentry_imm[g] = fnHasConst(iqentry_op[g]);
 
assign args_valid[g] =
                        (iqentry_p_v[g]
                                || (iqentry_p_s[g]==alu0_sourceid && alu0_v)
                                || (iqentry_p_s[g]==alu1_sourceid && alu1_v))
                        && (iqentry_a1_v[g]
//                              || (iqentry_mem[g] && !iqentry_agen[g] && iqentry_op[g]!=`TLB)
                                || (iqentry_a1_s[g] == alu0_sourceid && alu0_v)
                                || (iqentry_a1_s[g] == alu1_sourceid && alu1_v))
                        && (iqentry_a2_v[g]
                                || (iqentry_a2_s[g] == alu0_sourceid && alu0_v)
                                || (iqentry_a2_s[g] == alu1_sourceid && alu1_v))
                        && (iqentry_a3_v[g]
                                || (iqentry_a3_s[g] == alu0_sourceid && alu0_v)
                                || (iqentry_a3_s[g] == alu1_sourceid && alu1_v))
                        && (iqentry_T_v[g]
                                || (iqentry_T_s[g] == alu0_sourceid && alu0_v)
                || (iqentry_T_s[g] == alu1_sourceid && alu1_v))
                        ;
 
assign could_issue[g] = iqentry_v[g] && !iqentry_done[g] && !iqentry_out[g] && args_valid[g] &&
                         (iqentry_mem[g] ? !iqentry_agen[g] : 1'b1);
 
end
end
endgenerate
 
// The (old) simulator didn't handle the asynchronous race loop properly in the 
// original code. It would issue two instructions to the same islot. So the
// issue logic has been re-written to eliminate the asynchronous loop.
// Can't issue to the ALU if it's busy doing a long running operation like a 
// divide.
always @*//(could_issue or head0 or head1 or head2 or head3 or head4 or head5 or head6 or head7)
begin
        iqentry_issue = 8'h00;
        iqentry_islot[0] = 2'b00;
        iqentry_islot[1] = 2'b00;
        iqentry_islot[2] = 2'b00;
        iqentry_islot[3] = 2'b00;
        iqentry_islot[4] = 2'b00;
        iqentry_islot[5] = 2'b00;
        iqentry_islot[6] = 2'b00;
        iqentry_islot[7] = 2'b00;
        if (could_issue[head0] & !iqentry_fp[head0] & alu0_idle) begin
                iqentry_issue[head0] = `TRUE;
                iqentry_islot[head0] = 2'b00;
        end
        else if (could_issue[head1] & !iqentry_fp[head1]  & alu0_idle
        && !(iqentry_v[head0] && iqentry_sync[head0]))
        begin
                iqentry_issue[head1] = `TRUE;
                iqentry_islot[head1] = 2'b00;
        end
        else if (could_issue[head2] & !iqentry_fp[head2] & alu0_idle
        && !(iqentry_v[head0] && iqentry_sync[head0])
        && !(iqentry_v[head1] && iqentry_sync[head1])
        )
        begin
                iqentry_issue[head2] = `TRUE;
                iqentry_islot[head2] = 2'b00;
        end
        else if (could_issue[head3] & !iqentry_fp[head3] & alu0_idle
        && !(iqentry_v[head0] && iqentry_sync[head0])
        && !(iqentry_v[head1] && iqentry_sync[head1])
        && !(iqentry_v[head2] && iqentry_sync[head2])
        ) begin
                iqentry_issue[head3] = `TRUE;
                iqentry_islot[head3] = 2'b00;
        end
        else if (could_issue[head4] & !iqentry_fp[head4] & alu0_idle
        && !(iqentry_v[head0] && iqentry_sync[head0])
        && !(iqentry_v[head1] && iqentry_sync[head1])
        && !(iqentry_v[head2] && iqentry_sync[head2])
        && !(iqentry_v[head3] && iqentry_sync[head3])
        ) begin
                iqentry_issue[head4] = `TRUE;
                iqentry_islot[head4] = 2'b00;
        end
        else if (could_issue[head5] & !iqentry_fp[head5] & alu0_idle
        && !(iqentry_v[head0] && iqentry_sync[head0])
        && !(iqentry_v[head1] && iqentry_sync[head1])
        && !(iqentry_v[head2] && iqentry_sync[head2])
        && !(iqentry_v[head3] && iqentry_sync[head3])
        && !(iqentry_v[head4] && iqentry_sync[head4])
        ) begin
                iqentry_issue[head5] = `TRUE;
                iqentry_islot[head5] = 2'b00;
        end
        else if (could_issue[head6] & !iqentry_fp[head6] & alu0_idle
        && !(iqentry_v[head0] && iqentry_sync[head0])
        && !(iqentry_v[head1] && iqentry_sync[head1])
        && !(iqentry_v[head2] && iqentry_sync[head2])
        && !(iqentry_v[head3] && iqentry_sync[head3])
        && !(iqentry_v[head4] && iqentry_sync[head4])
        && !(iqentry_v[head5] && iqentry_sync[head5])
        ) begin
                iqentry_issue[head6] = `TRUE;
                iqentry_islot[head6] = 2'b00;
        end
        else if (could_issue[head7] & !iqentry_fp[head7] & alu0_idle
        && !(iqentry_v[head0] && iqentry_sync[head0])
        && !(iqentry_v[head1] && iqentry_sync[head1])
        && !(iqentry_v[head2] && iqentry_sync[head2])
        && !(iqentry_v[head3] && iqentry_sync[head3])
        && !(iqentry_v[head4] && iqentry_sync[head4])
        && !(iqentry_v[head5] && iqentry_sync[head5])
        && !(iqentry_v[head6] && iqentry_sync[head6])
        ) begin
                iqentry_issue[head7] = `TRUE;
                iqentry_islot[head7] = 2'b00;
        end
 
    // Don't bother checking head0, it should have issued to the first
    // instruction.
        if (could_issue[head1] && !iqentry_fp[head1] && !iqentry_issue[head1] & alu1_idle
        && !fnIsAlu0Op(iqentry_op[head1],iqentry_fn[head1])
        && !(iqentry_v[head0] && iqentry_sync[head0]))
        begin
                iqentry_issue[head1] = `TRUE;
                iqentry_islot[head1] = 2'b01;
        end
        else if (could_issue[head2] && !iqentry_fp[head2] && !iqentry_issue[head2] & alu1_idle
        && !fnIsAlu0Op(iqentry_op[head2],iqentry_fn[head2])
        && !(iqentry_v[head0] && iqentry_sync[head0])
        && !(iqentry_v[head1] && iqentry_sync[head1])
        )
        begin
                iqentry_issue[head2] = `TRUE;
                iqentry_islot[head2] = 2'b01;
        end
        else if (could_issue[head3] & !iqentry_fp[head3] && !iqentry_issue[head3] & alu1_idle
        && !fnIsAlu0Op(iqentry_op[head3],iqentry_fn[head3])
        && !(iqentry_v[head0] && iqentry_sync[head0])
        && !(iqentry_v[head1] && iqentry_sync[head1])
        && !(iqentry_v[head2] && iqentry_sync[head2])
        ) begin
                iqentry_issue[head3] = `TRUE;
                iqentry_islot[head3] = 2'b01;
        end
        else if (could_issue[head4] & !iqentry_fp[head4] && !iqentry_issue[head4] & alu1_idle
        && !fnIsAlu0Op(iqentry_op[head4],iqentry_fn[head4])
        && !(iqentry_v[head0] && iqentry_sync[head0])
        && !(iqentry_v[head1] && iqentry_sync[head1])
        && !(iqentry_v[head2] && iqentry_sync[head2])
        && !(iqentry_v[head3] && iqentry_sync[head3])
        ) begin
                iqentry_issue[head4] = `TRUE;
                iqentry_islot[head4] = 2'b01;
        end
        else if (could_issue[head5] & !iqentry_fp[head5] && !iqentry_issue[head5] & alu1_idle
        && !fnIsAlu0Op(iqentry_op[head5],iqentry_fn[head5])
        && !(iqentry_v[head0] && iqentry_sync[head0])
        && !(iqentry_v[head1] && iqentry_sync[head1])
        && !(iqentry_v[head2] && iqentry_sync[head2])
        && !(iqentry_v[head3] && iqentry_sync[head3])
        && !(iqentry_v[head4] && iqentry_sync[head4])
        ) begin
                iqentry_issue[head5] = `TRUE;
                iqentry_islot[head5] = 2'b01;
        end
        else if (could_issue[head6] & !iqentry_fp[head6] && !iqentry_issue[head6] & alu1_idle
        && !fnIsAlu0Op(iqentry_op[head6],iqentry_fn[head6])
        && !(iqentry_v[head0] && iqentry_sync[head0])
        && !(iqentry_v[head1] && iqentry_sync[head1])
        && !(iqentry_v[head2] && iqentry_sync[head2])
        && !(iqentry_v[head3] && iqentry_sync[head3])
        && !(iqentry_v[head4] && iqentry_sync[head4])
        && !(iqentry_v[head5] && iqentry_sync[head5])
        ) begin
                iqentry_issue[head6] = `TRUE;
                iqentry_islot[head6] = 2'b01;
        end
        else if (could_issue[head7] & !iqentry_fp[head7] && !iqentry_issue[head7] & alu1_idle
        && !fnIsAlu0Op(iqentry_op[head7],iqentry_fn[head7])
        && !(iqentry_v[head0] && iqentry_sync[head0])
        && !(iqentry_v[head1] && iqentry_sync[head1])
        && !(iqentry_v[head2] && iqentry_sync[head2])
        && !(iqentry_v[head3] && iqentry_sync[head3])
        && !(iqentry_v[head4] && iqentry_sync[head4])
        && !(iqentry_v[head5] && iqentry_sync[head5])
        && !(iqentry_v[head6] && iqentry_sync[head6])
        ) begin
                iqentry_issue[head7] = `TRUE;
                iqentry_islot[head7] = 2'b01;
        end
end
 
 
`ifdef FLOATING_POINT
reg [3:0] fpispot;
always @(could_issue or head0 or head1 or head2 or head3 or head4 or head5 or head6 or head7)
begin
        iqentry_fpissue = 8'h00;
        iqentry_fpislot[0] = 2'b00;
        iqentry_fpislot[1] = 2'b00;
        iqentry_fpislot[2] = 2'b00;
        iqentry_fpislot[3] = 2'b00;
        iqentry_fpislot[4] = 2'b00;
        iqentry_fpislot[5] = 2'b00;
        iqentry_fpislot[6] = 2'b00;
        iqentry_fpislot[7] = 2'b00;
        fpispot = head0;
        if (could_issue[head0] & iqentry_fp[head0]) begin
                iqentry_fpissue[head0] = `TRUE;
                iqentry_fpislot[head0] = 2'b00;
                fpispot = head0;
        end
        else if (could_issue[head1] & iqentry_fp[head1]
        && !(iqentry_v[head0] && iqentry_sync[head0]))
        begin
                iqentry_fpissue[head1] = `TRUE;
                iqentry_fpislot[head1] = 2'b00;
                fpispot = head1;
        end
        else if (could_issue[head2] & iqentry_fp[head2]
        && !(iqentry_v[head0] && iqentry_sync[head0])
        && !(iqentry_v[head1] && iqentry_sync[head1])
        )
        begin
                iqentry_fpissue[head2] = `TRUE;
                iqentry_fpislot[head2] = 2'b00;
                fpispot = head2;
        end
        else if (could_issue[head3] & iqentry_fp[head3]
        && !(iqentry_v[head0] && iqentry_sync[head0])
        && !(iqentry_v[head1] && iqentry_sync[head1])
        && !(iqentry_v[head2] && iqentry_sync[head2])
        ) begin
                iqentry_fpissue[head3] = `TRUE;
                iqentry_fpislot[head3] = 2'b00;
                fpispot = head3;
        end
        else if (could_issue[head4] & iqentry_fp[head4]
        && !(iqentry_v[head0] && iqentry_sync[head0])
        && !(iqentry_v[head1] && iqentry_sync[head1])
        && !(iqentry_v[head2] && iqentry_sync[head2])
        && !(iqentry_v[head3] && iqentry_sync[head3])
        ) begin
                iqentry_fpissue[head4] = `TRUE;
                iqentry_fpislot[head4] = 2'b00;
                fpispot = head4;
        end
        else if (could_issue[head5] & iqentry_fp[head5]
        && !(iqentry_v[head0] && iqentry_sync[head0])
        && !(iqentry_v[head1] && iqentry_sync[head1])
        && !(iqentry_v[head2] && iqentry_sync[head2])
        && !(iqentry_v[head3] && iqentry_sync[head3])
        && !(iqentry_v[head4] && iqentry_sync[head4])
        ) begin
                iqentry_fpissue[head5] = `TRUE;
                iqentry_fpislot[head5] = 2'b00;
                fpispot = head5;
        end
        else if (could_issue[head6] & iqentry_fp[head6]
        && !(iqentry_v[head0] && iqentry_sync[head0])
        && !(iqentry_v[head1] && iqentry_sync[head1])
        && !(iqentry_v[head2] && iqentry_sync[head2])
        && !(iqentry_v[head3] && iqentry_sync[head3])
        && !(iqentry_v[head4] && iqentry_sync[head4])
        && !(iqentry_v[head5] && iqentry_sync[head5])
        ) begin
                iqentry_fpissue[head6] = `TRUE;
                iqentry_fpislot[head6] = 2'b00;
                fpispot = head6;
        end
        else if (could_issue[head7] & iqentry_fp[head7]
        && !(iqentry_v[head0] && iqentry_sync[head0])
        && !(iqentry_v[head1] && iqentry_sync[head1])
        && !(iqentry_v[head2] && iqentry_sync[head2])
        && !(iqentry_v[head3] && iqentry_sync[head3])
        && !(iqentry_v[head4] && iqentry_sync[head4])
        && !(iqentry_v[head5] && iqentry_sync[head5])
        && !(iqentry_v[head6] && iqentry_sync[head6])
        ) begin
                iqentry_fpissue[head7] = `TRUE;
                iqentry_fpislot[head7] = 2'b00;
                fpispot = head7;
        end
        else
                fpispot = 4'd8;
 
end
`endif
 
// 
// additional logic for handling a branch miss (STOMP logic)
//
wire [QENTRIES-1:0] alu0_issue_;
wire [QENTRIES-1:0] alu1_issue_;
wire [QENTRIES-1:0] fp0_issue_;
generate
begin : stomp_logic
assign iqentry_stomp[0] = branchmiss & (iqentry_v[0] && head0 != 3'd0 && ((missid == QENTRIES-1) || iqentry_stomp[QENTRIES-1]));
for (g = 1; g < QENTRIES; g = g + 1)
assign iqentry_stomp[g] = branchmiss & (iqentry_v[g] && head0 != g && ((missid == g-1) || iqentry_stomp[g-1]));
for (g = 0; g < QENTRIES; g = g + 1)
begin
assign alu0_issue_[g] = (!(iqentry_v[g] && iqentry_stomp[g]) && iqentry_issue[g] && iqentry_islot[g]==2'd0);
assign alu1_issue_[g] = (!(iqentry_v[g] && iqentry_stomp[g]) && iqentry_issue[g] && iqentry_islot[g]==2'd1);
assign fp0_issue_[g] = (!(iqentry_v[g] && iqentry_stomp[g]) && iqentry_fpissue[g] && iqentry_islot[g]==2'd0);
end
end
endgenerate
 
assign alu0_issue = |alu0_issue_;
assign alu1_issue = |alu1_issue_;
`ifdef FLOATING_POINT
assign fp0_issue = |fp0_issue_;
`endif
 
wire dcache_access_pending = dram0 == 3'd6 && (!rhit || (dram0_op==`LCL && dram0_tgt==7'd1));
 
//
// determine if the instructions ready to issue can, in fact, issue.
// "ready" means that the instruction has valid operands but has not gone yet
//
// Stores can only issue if there is no possibility of a change of program flow.
// That means no flow control operations or instructions that can cause an
// exception can be before the store.
 
// ToDo: if debugging matches are enabled in theory any instruction could cause
// a debug exception. The memory issue logic should check to see a debug address
// match will occur, and avoid a store operation. It may be simpler to have stores
// only occur if they are at the head of the queue if debugging matches are turned
// on.
assign iqentry_memissue_head0 = iqentry_memready[ head0 ] && cstate==IDLE && !dcache_access_pending && dram0==0;         // first in line ... go as soon as ready
 
assign iqentry_memissue_head1 = ~iqentry_stomp[head1] && iqentry_memready[ head1 ]              // addr and data are valid
                                // ... and no preceding instruction is ready to go
                                && ~iqentry_memready[head0]
                                // ... and there is no address-overlap with any preceding instruction
                                && (!iqentry_mem[head0] || (iqentry_agen[head0] & iqentry_out[head0])
                                        || (iqentry_a1_v[head0] && iqentry_a1[head1][DBW-1:3] != iqentry_a1[head0][DBW-1:3]))
                                // ... and, if it is a SW, there is no chance of it being undone
                                && (fnIsStore(iqentry_op[head1]) ? !fnIsFlowCtrl(iqentry_op[head0])
                                && !fnCanException(iqentry_op[head0],iqentry_fn[head0]) : `TRUE)
                                && (!iqentry_cas[head1])
                                && !(iqentry_v[head0] && fnIsMem(iqentry_op[head0]) && iqentry_memdb[head0])
                                && !(iqentry_v[head0] && iqentry_memsb[head0])
                                && cstate==IDLE && !dcache_access_pending && dram0==0
                                ;
 
assign iqentry_memissue_head2 = ~iqentry_stomp[head2] && iqentry_memready[ head2 ]              // addr and data are valid
                                // ... and no preceding instruction is ready to go
                                && ~iqentry_memready[head0]
                                && ~iqentry_memready[head1]
                                // ... and there is no address-overlap with any preceding instruction
                                && (!iqentry_mem[head0] || (iqentry_agen[head0] & iqentry_out[head0])
                                        || (iqentry_a1_v[head0] && iqentry_a1[head2][DBW-1:3] != iqentry_a1[head0][DBW-1:3]))
                                && (!iqentry_mem[head1] || (iqentry_agen[head1] & iqentry_out[head1])
                                        || (iqentry_a1_v[head1] && iqentry_a1[head2][DBW-1:3] != iqentry_a1[head1][DBW-1:3]))
                                // ... and, if it is a SW, there is no chance of it being undone
                                && (fnIsStore(iqentry_op[head2]) ?
                                    !fnIsFlowCtrl(iqentry_op[head0]) && !fnCanException(iqentry_op[head0],iqentry_fn[head0]) &&
                                    !fnIsFlowCtrl(iqentry_op[head1]) && !fnCanException(iqentry_op[head1],iqentry_fn[head1])
                                    : `TRUE)
                                && (!iqentry_cas[head2])
                                && !(iqentry_v[head0] && fnIsMem(iqentry_op[head0]) && iqentry_memdb[head0])
                                && !(iqentry_v[head1] && fnIsMem(iqentry_op[head1]) && iqentry_memdb[head1])
                                // ... and there is no instruction barrier
                                && !(iqentry_v[head0] && iqentry_memsb[head0])
                                && !(iqentry_v[head1] && iqentry_memsb[head1])
                                && cstate==IDLE && !dcache_access_pending && dram0==0
                                ;
//                                      (   !fnIsFlowCtrl(iqentry_op[head0])
//                                       && !fnIsFlowCtrl(iqentry_op[head1])));
 
assign iqentry_memissue_head3 = ~iqentry_stomp[head3] && iqentry_memready[ head3 ]      // addr and data are valid
                                // ... and no preceding instruction is ready to go
                                && ~iqentry_memready[head0]
                                && ~iqentry_memready[head1]
                                && ~iqentry_memready[head2]
                                // ... and there is no address-overlap with any preceding instruction
                                && (!iqentry_mem[head0] || (iqentry_agen[head0] & iqentry_out[head0])
                                        || (iqentry_a1_v[head0] && iqentry_a1[head3][DBW-1:3] != iqentry_a1[head0][DBW-1:3]))
                                && (!iqentry_mem[head1] || (iqentry_agen[head1] & iqentry_out[head1])
                                        || (iqentry_a1_v[head1] && iqentry_a1[head3][DBW-1:3] != iqentry_a1[head1][DBW-1:3]))
                                && (!iqentry_mem[head2] || (iqentry_agen[head2] & iqentry_out[head2])
                                        || (iqentry_a1_v[head2] && iqentry_a1[head3][DBW-1:3] != iqentry_a1[head2][DBW-1:3]))
                                // ... and, if it is a SW, there is no chance of it being undone
                                && (fnIsStore(iqentry_op[head3]) ?
                    !fnIsFlowCtrl(iqentry_op[head0]) && !fnCanException(iqentry_op[head0],iqentry_fn[head0]) &&
                    !fnIsFlowCtrl(iqentry_op[head1]) && !fnCanException(iqentry_op[head1],iqentry_fn[head1]) &&
                    !fnIsFlowCtrl(iqentry_op[head2]) && !fnCanException(iqentry_op[head2],iqentry_fn[head2])
                    : `TRUE)
                                && (!iqentry_cas[head3])
                                // ... and there is no memory barrier
                                && !(iqentry_v[head0] && fnIsMem(iqentry_op[head0]) && iqentry_memdb[head0])
                                && !(iqentry_v[head1] && fnIsMem(iqentry_op[head1]) && iqentry_memdb[head1])
                                && !(iqentry_v[head2] && fnIsMem(iqentry_op[head2]) && iqentry_memdb[head2])
                                // ... and there is no instruction barrier
                                && !(iqentry_v[head0] && iqentry_memsb[head0])
                && !(iqentry_v[head1] && iqentry_memsb[head1])
                && !(iqentry_v[head2] && iqentry_memsb[head2])
                                && cstate==IDLE && !dcache_access_pending && dram0==0
                                ;
/*                                      (   !fnIsFlowCtrl(iqentry_op[head0])
                                         && !fnIsFlowCtrl(iqentry_op[head1])
                                         && !fnIsFlowCtrl(iqentry_op[head2])));
*/
assign iqentry_memissue_head4 = ~iqentry_stomp[head4] && iqentry_memready[ head4 ]              // addr and data are valid
                                // ... and no preceding instruction is ready to go
                                && ~iqentry_memready[head0]
                                && ~iqentry_memready[head1]
                                && ~iqentry_memready[head2]
                                && ~iqentry_memready[head3]
                                // ... and there is no address-overlap with any preceding instruction
                                && (!iqentry_mem[head0] || (iqentry_agen[head0] & iqentry_out[head0])
                                        || (iqentry_a1_v[head0] && iqentry_a1[head4][DBW-1:3] != iqentry_a1[head0][DBW-1:3]))
                                && (!iqentry_mem[head1] || (iqentry_agen[head1] & iqentry_out[head1])
                                        || (iqentry_a1_v[head1] && iqentry_a1[head4][DBW-1:3] != iqentry_a1[head1][DBW-1:3]))
                                && (!iqentry_mem[head2] || (iqentry_agen[head2] & iqentry_out[head2])
                                        || (iqentry_a1_v[head2] && iqentry_a1[head4][DBW-1:3] != iqentry_a1[head2][DBW-1:3]))
                                && (!iqentry_mem[head3] || (iqentry_agen[head3] & iqentry_out[head3])
                                        || (iqentry_a1_v[head3] && iqentry_a1[head4][DBW-1:3] != iqentry_a1[head3][DBW-1:3]))
                                // ... and, if it is a SW, there is no chance of it being undone
                                && (fnIsStore(iqentry_op[head4]) ?
                    !fnIsFlowCtrl(iqentry_op[head0]) && !fnCanException(iqentry_op[head0],iqentry_fn[head0]) &&
                    !fnIsFlowCtrl(iqentry_op[head1]) && !fnCanException(iqentry_op[head1],iqentry_fn[head1]) &&
                    !fnIsFlowCtrl(iqentry_op[head2]) && !fnCanException(iqentry_op[head2],iqentry_fn[head2]) &&
                    !fnIsFlowCtrl(iqentry_op[head3]) && !fnCanException(iqentry_op[head3],iqentry_fn[head3])
                    : `TRUE)
                                && (!iqentry_cas[head4])
                                // ... and there is no memory barrier
                                && !(iqentry_v[head0] && fnIsMem(iqentry_op[head0]) && iqentry_memdb[head0])
                                && !(iqentry_v[head1] && fnIsMem(iqentry_op[head1]) && iqentry_memdb[head1])
                                && !(iqentry_v[head2] && fnIsMem(iqentry_op[head2]) && iqentry_memdb[head2])
                                && !(iqentry_v[head3] && fnIsMem(iqentry_op[head3]) && iqentry_memdb[head3])
                                // ... and there is no instruction barrier
                                && !(iqentry_v[head0] && iqentry_memsb[head0])
                && !(iqentry_v[head1] && iqentry_memsb[head1])
                && !(iqentry_v[head2] && iqentry_memsb[head2])
                && !(iqentry_v[head3] && iqentry_memsb[head3])
                                && cstate==IDLE && !dcache_access_pending && dram0==0
                                ;
/* ||
                                        (   !fnIsFlowCtrl(iqentry_op[head0])
                                         && !fnIsFlowCtrl(iqentry_op[head1])
                                         && !fnIsFlowCtrl(iqentry_op[head2])
                                         && !fnIsFlowCtrl(iqentry_op[head3])));
*/
assign iqentry_memissue_head5 = ~iqentry_stomp[head5] && iqentry_memready[ head5 ]              // addr and data are valid
                                // ... and no preceding instruction is ready to go
                                && ~iqentry_memready[head0]
                                && ~iqentry_memready[head1]
                                && ~iqentry_memready[head2]
                                && ~iqentry_memready[head3]
                                && ~iqentry_memready[head4]
                                // ... and there is no address-overlap with any preceding instruction
                                && (!iqentry_mem[head0] || (iqentry_agen[head0] & iqentry_out[head0])
                                        || (iqentry_a1_v[head0] && iqentry_a1[head5][DBW-1:3] != iqentry_a1[head0][DBW-1:3]))
                                && (!iqentry_mem[head1] || (iqentry_agen[head1] & iqentry_out[head1])
                                        || (iqentry_a1_v[head1] && iqentry_a1[head5][DBW-1:3] != iqentry_a1[head1][DBW-1:3]))
                                && (!iqentry_mem[head2] || (iqentry_agen[head2] & iqentry_out[head2])
                                        || (iqentry_a1_v[head2] && iqentry_a1[head5][DBW-1:3] != iqentry_a1[head2][DBW-1:3]))
                                && (!iqentry_mem[head3] || (iqentry_agen[head3] & iqentry_out[head3])
                                        || (iqentry_a1_v[head3] && iqentry_a1[head5][DBW-1:3] != iqentry_a1[head3][DBW-1:3]))
                                && (!iqentry_mem[head4] || (iqentry_agen[head4] & iqentry_out[head4])
                                        || (iqentry_a1_v[head4] && iqentry_a1[head5][DBW-1:3] != iqentry_a1[head4][DBW-1:3]))
                                // ... and, if it is a SW, there is no chance of it being undone
                                && (fnIsStore(iqentry_op[head5]) ?
                    !fnIsFlowCtrl(iqentry_op[head0]) && !fnCanException(iqentry_op[head0],iqentry_fn[head0]) &&
                    !fnIsFlowCtrl(iqentry_op[head1]) && !fnCanException(iqentry_op[head1],iqentry_fn[head1]) &&
                    !fnIsFlowCtrl(iqentry_op[head2]) && !fnCanException(iqentry_op[head2],iqentry_fn[head2]) &&
                    !fnIsFlowCtrl(iqentry_op[head3]) && !fnCanException(iqentry_op[head3],iqentry_fn[head3]) &&
                    !fnIsFlowCtrl(iqentry_op[head4]) && !fnCanException(iqentry_op[head4],iqentry_fn[head4])
                    : `TRUE)
                                && (!iqentry_cas[head5])
                                // ... and there is no memory barrier
                                && !(iqentry_v[head0] && fnIsMem(iqentry_op[head0]) && iqentry_memdb[head0])
                                && !(iqentry_v[head1] && fnIsMem(iqentry_op[head1]) && iqentry_memdb[head1])
                                && !(iqentry_v[head2] && fnIsMem(iqentry_op[head2]) && iqentry_memdb[head2])
                                && !(iqentry_v[head3] && fnIsMem(iqentry_op[head3]) && iqentry_memdb[head3])
                                && !(iqentry_v[head4] && fnIsMem(iqentry_op[head4]) && iqentry_memdb[head4])
                                // ... and there is no instruction barrier
                                && !(iqentry_v[head0] && iqentry_memsb[head0])
                && !(iqentry_v[head1] && iqentry_memsb[head1])
                && !(iqentry_v[head2] && iqentry_memsb[head2])
                && !(iqentry_v[head3] && iqentry_memsb[head3])
                && !(iqentry_v[head4] && iqentry_memsb[head4])
                                && cstate==IDLE && !dcache_access_pending && dram0==0
                                ;
/*||
                                        (   !fnIsFlowCtrl(iqentry_op[head0])
                                         && !fnIsFlowCtrl(iqentry_op[head1])
                                         && !fnIsFlowCtrl(iqentry_op[head2])
                                         && !fnIsFlowCtrl(iqentry_op[head3])
                                         && !fnIsFlowCtrl(iqentry_op[head4])));
*/
assign iqentry_memissue_head6 = ~iqentry_stomp[head6] && iqentry_memready[ head6 ]              // addr and data are valid
                                // ... and no preceding instruction is ready to go
                                && ~iqentry_memready[head0]
                                && ~iqentry_memready[head1]
                                && ~iqentry_memready[head2]
                                && ~iqentry_memready[head3]
                                && ~iqentry_memready[head4]
                                && ~iqentry_memready[head5]
                                // ... and there is no address-overlap with any preceding instruction
                                && (!iqentry_mem[head0] || (iqentry_agen[head0] & iqentry_out[head0])
                                        || (iqentry_a1_v[head0] && iqentry_a1[head6][DBW-1:3] != iqentry_a1[head0][DBW-1:3]))
                                && (!iqentry_mem[head1] || (iqentry_agen[head1] & iqentry_out[head1])
                                        || (iqentry_a1_v[head1] && iqentry_a1[head6][DBW-1:3] != iqentry_a1[head1][DBW-1:3]))
                                && (!iqentry_mem[head2] || (iqentry_agen[head2] & iqentry_out[head2])
                                        || (iqentry_a1_v[head2] && iqentry_a1[head6][DBW-1:3] != iqentry_a1[head2][DBW-1:3]))
                                && (!iqentry_mem[head3] || (iqentry_agen[head3] & iqentry_out[head3])
                                        || (iqentry_a1_v[head3] && iqentry_a1[head6][DBW-1:3] != iqentry_a1[head3][DBW-1:3]))
                                && (!iqentry_mem[head4] || (iqentry_agen[head4] & iqentry_out[head4])
                                        || (iqentry_a1_v[head4] && iqentry_a1[head6][DBW-1:3] != iqentry_a1[head4][DBW-1:3]))
                                && (!iqentry_mem[head5] || (iqentry_agen[head5] & iqentry_out[head5])
                                        || (iqentry_a1_v[head5] && iqentry_a1[head6][DBW-1:3] != iqentry_a1[head5][DBW-1:3]))
                                // ... and, if it is a SW, there is no chance of it being undone
                                && (fnIsStore(iqentry_op[head6]) ?
                    !fnIsFlowCtrl(iqentry_op[head0]) && !fnCanException(iqentry_op[head0],iqentry_fn[head0]) &&
                    !fnIsFlowCtrl(iqentry_op[head1]) && !fnCanException(iqentry_op[head1],iqentry_fn[head1]) &&
                    !fnIsFlowCtrl(iqentry_op[head2]) && !fnCanException(iqentry_op[head2],iqentry_fn[head2]) &&
                    !fnIsFlowCtrl(iqentry_op[head3]) && !fnCanException(iqentry_op[head3],iqentry_fn[head3]) &&
                    !fnIsFlowCtrl(iqentry_op[head4]) && !fnCanException(iqentry_op[head4],iqentry_fn[head4]) &&
                    !fnIsFlowCtrl(iqentry_op[head5]) && !fnCanException(iqentry_op[head5],iqentry_fn[head5])
                    : `TRUE)
                                && (!iqentry_cas[head6])
                                // ... and there is no memory barrier
                                && !(iqentry_v[head0] && fnIsMem(iqentry_op[head0]) && iqentry_memdb[head0])
                                && !(iqentry_v[head1] && fnIsMem(iqentry_op[head1]) && iqentry_memdb[head1])
                                && !(iqentry_v[head2] && fnIsMem(iqentry_op[head2]) && iqentry_memdb[head2])
                                && !(iqentry_v[head3] && fnIsMem(iqentry_op[head3]) && iqentry_memdb[head3])
                                && !(iqentry_v[head4] && fnIsMem(iqentry_op[head4]) && iqentry_memdb[head4])
                                && !(iqentry_v[head5] && fnIsMem(iqentry_op[head5]) && iqentry_memdb[head5])
                                // ... and there is no instruction barrier
                                && !(iqentry_v[head0] && iqentry_memsb[head0])
                && !(iqentry_v[head1] && iqentry_memsb[head1])
                && !(iqentry_v[head2] && iqentry_memsb[head2])
                && !(iqentry_v[head3] && iqentry_memsb[head3])
                && !(iqentry_v[head4] && iqentry_memsb[head4])
                && !(iqentry_v[head5] && iqentry_memsb[head5])
                                && cstate==IDLE && !dcache_access_pending && dram0==0
                                ;
                                /*||
                                        (   !fnIsFlowCtrl(iqentry_op[head0])
                                         && !fnIsFlowCtrl(iqentry_op[head1])
                                         && !fnIsFlowCtrl(iqentry_op[head2])
                                         && !fnIsFlowCtrl(iqentry_op[head3])
                                         && !fnIsFlowCtrl(iqentry_op[head4])
                                         && !fnIsFlowCtrl(iqentry_op[head5])));
*/
assign iqentry_memissue_head7 = ~iqentry_stomp[head7] && iqentry_memready[ head7 ]              // addr and data are valid
                                // ... and no preceding instruction is ready to go
                                && ~iqentry_memready[head0]
                                && ~iqentry_memready[head1]
                                && ~iqentry_memready[head2]
                                && ~iqentry_memready[head3]
                                && ~iqentry_memready[head4]
                                && ~iqentry_memready[head5]
                                && ~iqentry_memready[head6]
                                // ... and there is no address-overlap with any preceding instruction
                                && (!iqentry_mem[head0] || (iqentry_agen[head0] & iqentry_out[head0])
                                        || (iqentry_a1_v[head0] && iqentry_a1[head7][DBW-1:3] != iqentry_a1[head0][DBW-1:3]))
                                && (!iqentry_mem[head1] || (iqentry_agen[head1] & iqentry_out[head1])
                                        || (iqentry_a1_v[head1] && iqentry_a1[head7][DBW-1:3] != iqentry_a1[head1][DBW-1:3]))
                                && (!iqentry_mem[head2] || (iqentry_agen[head2] & iqentry_out[head2])
                                        || (iqentry_a1_v[head2] && iqentry_a1[head7][DBW-1:3] != iqentry_a1[head2][DBW-1:3]))
                                && (!iqentry_mem[head3] || (iqentry_agen[head3] & iqentry_out[head3])
                                        || (iqentry_a1_v[head3] && iqentry_a1[head7][DBW-1:3] != iqentry_a1[head3][DBW-1:3]))
                                && (!iqentry_mem[head4] || (iqentry_agen[head4] & iqentry_out[head4])
                                        || (iqentry_a1_v[head4] && iqentry_a1[head7][DBW-1:3] != iqentry_a1[head4][DBW-1:3]))
                                && (!iqentry_mem[head5] || (iqentry_agen[head5] & iqentry_out[head5])
                                        || (iqentry_a1_v[head5] && iqentry_a1[head7][DBW-1:3] != iqentry_a1[head5][DBW-1:3]))
                                && (!iqentry_mem[head6] || (iqentry_agen[head6] & iqentry_out[head6])
                                        || (iqentry_a1_v[head6] && iqentry_a1[head7][DBW-1:3] != iqentry_a1[head6][DBW-1:3]))
                                // ... and, if it is a SW, there is no chance of it being undone
                                && (fnIsStore(iqentry_op[head7]) ?
                    !fnIsFlowCtrl(iqentry_op[head0]) && !fnCanException(iqentry_op[head0],iqentry_fn[head0]) &&
                    !fnIsFlowCtrl(iqentry_op[head1]) && !fnCanException(iqentry_op[head1],iqentry_fn[head1]) &&
                    !fnIsFlowCtrl(iqentry_op[head2]) && !fnCanException(iqentry_op[head2],iqentry_fn[head2]) &&
                    !fnIsFlowCtrl(iqentry_op[head3]) && !fnCanException(iqentry_op[head3],iqentry_fn[head3]) &&
                    !fnIsFlowCtrl(iqentry_op[head4]) && !fnCanException(iqentry_op[head4],iqentry_fn[head4]) &&
                    !fnIsFlowCtrl(iqentry_op[head5]) && !fnCanException(iqentry_op[head5],iqentry_fn[head5]) &&
                    !fnIsFlowCtrl(iqentry_op[head6]) && !fnCanException(iqentry_op[head6],iqentry_fn[head6])
                    : `TRUE)
                                && (!iqentry_cas[head7])
                                // ... and there is no memory barrier
                                && !(iqentry_v[head0] && fnIsMem(iqentry_op[head0]) && iqentry_memdb[head0])
                                && !(iqentry_v[head1] && fnIsMem(iqentry_op[head1]) && iqentry_memdb[head1])
                                && !(iqentry_v[head2] && fnIsMem(iqentry_op[head2]) && iqentry_memdb[head2])
                                && !(iqentry_v[head3] && fnIsMem(iqentry_op[head3]) && iqentry_memdb[head3])
                                && !(iqentry_v[head4] && fnIsMem(iqentry_op[head4]) && iqentry_memdb[head4])
                                && !(iqentry_v[head5] && fnIsMem(iqentry_op[head5]) && iqentry_memdb[head5])
                                && !(iqentry_v[head6] && fnIsMem(iqentry_op[head6]) && iqentry_memdb[head6])
                                // ... and there is no instruction barrier
                                && !(iqentry_v[head0] && iqentry_memsb[head0])
                && !(iqentry_v[head1] && iqentry_memsb[head1])
                && !(iqentry_v[head2] && iqentry_memsb[head2])
                && !(iqentry_v[head3] && iqentry_memsb[head3])
                && !(iqentry_v[head4] && iqentry_memsb[head4])
                && !(iqentry_v[head5] && iqentry_memsb[head5])
                && !(iqentry_v[head6] && iqentry_memsb[head6])
                                && cstate==IDLE && !dcache_access_pending && dram0==0
                                ;
 
`include "Thor_execute_combo.v"
//`include "Thor_memory_combo.v"
// additional DRAM-enqueue logic
 
Thor_TLB #(DBW) utlb1
(
        .rst(rst_i),
        .clk(clk),
        .km(km),
        .pc(spc),
        .ea(dram0_addr),
        .ppc(ppc),
        .pea(pea),
        .iuncached(iuncached),
        .uncached(uncached),
        .m1IsStore(we_o),
        .ASID(asid),
        .op(tlb_op),
        .state(tlb_state),
        .regno(tlb_regno),
        .dati(tlb_data),
        .dato(tlb_dato),
        .ITLBMiss(ITLBMiss),
        .DTLBMiss(DTLBMiss),
        .HTLBVirtPageo()
);
 
assign dram_avail = (dram0 == `DRAMSLOT_AVAIL || dram1 == `DRAMSLOT_AVAIL || dram2 == `DRAMSLOT_AVAIL);
 
generate
begin : memr
    for (g = 0; g < QENTRIES; g = g + 1)
    begin
assign iqentry_memopsvalid[g] = (iqentry_mem[g] & iqentry_a2_v[g] & iqentry_a3_v[g] & iqentry_agen[g] & iqentry_T_v[g]);
assign iqentry_memready[g] = (iqentry_v[g] & iqentry_memopsvalid[g] & ~iqentry_memissue[g] /*& !iqentry_issue[g]*/ & ~iqentry_done[g] & ~iqentry_out[g] & ~iqentry_stomp[g]);
    end
end
endgenerate
 
/*
assign
    iqentry_memready[0] = (iqentry_v[0] & iqentry_memopsvalid[0] & ~iqentry_memissue[0] & ~iqentry_done[0] & ~iqentry_out[0] & ~iqentry_stomp[0]),
*/
assign outstanding_stores = (dram0 && fnIsStore(dram0_op)) || (dram1 && fnIsStore(dram1_op)) || (dram2 && fnIsStore(dram2_op));
 
// This signal needed to stave off an instruction cache access.
assign mem_issue =
    iqentry_memissue_head0 |
    iqentry_memissue_head1 |
    iqentry_memissue_head2 |
    iqentry_memissue_head3 |
    iqentry_memissue_head4 |
    iqentry_memissue_head5 |
    iqentry_memissue_head6 |
    iqentry_memissue_head7
    ;
 
// Nybble slices for predicate register forwarding
wire [3:0] alu0nyb[0:15];
wire [3:0] alu1nyb[0:15];
wire [3:0] cmt0nyb[0:15];
wire [3:0] cmt1nyb[0:15];
 
generate
begin : nybs
    for (g = 0; g < DBW/4; g = g + 1)
    begin
assign alu0nyb[g] = alu0_bus[g*4+3:g*4];
assign alu1nyb[g] = alu1_bus[g*4+3:g*4];
assign cmt0nyb[g] = commit0_bus[g*4+3:g*4];
assign cmt1nyb[g] = commit1_bus[g*4+3:g*4];
    end
end
endgenerate
 
//`include "Thor_commit_combo.v"
 
assign commit0_v = ({iqentry_v[head0], iqentry_done[head0]} == 2'b11 && ~|panic);
assign commit1_v = ({iqentry_v[head0], iqentry_done[head0]} != 2'b10
                && {iqentry_v[head1], iqentry_done[head1]} == 2'b11 && ~|panic);
 
assign commit0_id = {iqentry_mem[head0], head0};        // if a memory op, it has a DRAM-bus id
assign commit1_id = {iqentry_mem[head1], head1};        // if a memory op, it has a DRAM-bus id
 
assign commit0_tgt = iqentry_tgt[head0];
assign commit1_tgt = iqentry_tgt[head1];
 
assign commit0_bus = iqentry_res[head0];
assign commit1_bus = iqentry_res[head1];
 
// If the target register is code address register #13 or #11 (0Dh) then we really wanted a SYS not an INT.
// The difference is that and INT returns to the interrupted instruction, and a SYS returns to the 
// next instruction. In the case of hardware determined software exceptions we want to be able to
// return to the interrupted instruction, hence an INT is forced targeting code address reg #13.
assign int_commit = (iqentry_op[head0]==`INT && commit0_v && iqentry_tgt[head0][3:0]==4'hE) ||
                    (commit0_v && iqentry_op[head1]==`INT && commit1_v && iqentry_tgt[head1][3:0]==4'hE);
assign sys_commit = ((iqentry_op[head0]==`SYS || (iqentry_op[head0]==`INT &&
                        (iqentry_tgt[head0][3:0]==4'hD || iqentry_tgt[head0][3:0]==4'hB))) && commit0_v) ||
                     (commit0_v && (iqentry_op[head1]==`SYS || (iqentry_op[head1]==`INT &&
                        (iqentry_tgt[head1][3:0]==4'hD || iqentry_tgt[head1][3:0]==4'hB))) && commit1_v);
`ifdef DEBUG_LOGIC
assign dbg_commit = (((iqentry_op[head0]==`SYS && iqentry_tgt[head0][3:0]==4'hB) ||
                      (iqentry_op[head0]==`INT && (iqentry_tgt[head0][3:0]==4'hB))) && commit0_v) ||
       (commit0_v && ((iqentry_op[head1]==`SYS && iqentry_tgt[head1][3:0]==4'hB)||
                      (iqentry_op[head1]==`INT && (iqentry_tgt[head1][3:0]==4'hB))) && commit1_v);
`endif
 
always @(posedge clk)
        if (rst_i)
                tick <= 64'd0;
        else
                tick <= tick + 64'd1;
 
always @(posedge clk)
        if (rst_i)
                nmi1 <= 1'b0;
        else
                nmi1 <= nmi_i;
 
//-----------------------------------------------------------------------------
// Clock control
// - reset or NMI reenables the clock
// - this circuit must be under the clk_i domain
//-----------------------------------------------------------------------------
//
reg cpu_clk_en;
reg [15:0] clk_throttle;
reg [15:0] clk_throttle_new;
reg ld_clk_throttle;
 
//BUFGCE u20 (.CE(cpu_clk_en), .I(clk_i), .O(clk) );
 
reg lct1;
always @(posedge clk_i)
if (rst_i) begin
        cpu_clk_en <= 1'b1;
        lct1 <= 1'b0;
        clk_throttle <= STARTUP_POWER;  // 50% power
end
else begin
        lct1 <= ld_clk_throttle;
        clk_throttle <= {clk_throttle[14:0],clk_throttle[15]};
        if (ld_clk_throttle && !lct1) begin
                clk_throttle <= clk_throttle_new;
    end
        if (nmi_i)
                clk_throttle <= STARTUP_POWER;
        cpu_clk_en <= clk_throttle[15];
end
 
// Clock throttling bypassed for now
assign clk_o = clk;
assign clk = clk_i;
 
//-----------------------------------------------------------------------------
// Note that everything clocked has to be in the same always block. This is a
// limitation of some toolsets. Simulation / synthesis may get confused if the
// logic isn't placed in the same always block.
//-----------------------------------------------------------------------------
 
always @(posedge clk) begin
 
        if (nmi_i & !nmi1)
                nmi_edge <= 1'b1;
 
        ld_clk_throttle <= `FALSE;
        dram_v <= `INV;
        alu0_ld <= 1'b0;
        alu1_ld <= 1'b0;
`ifdef FLOATING_POINT
        fp0_ld <= 1'b0;
`endif
 
    // Interrupt enable countdown delay.    
    if (imcd!=6'h3f)
        imcd <= {imcd[4:0],1'b0};
    if (imcd==6'd0) begin
        im <= 1'b0;
        imcd <= 6'h3f;
    end
 
    mem_stringmiss <= `FALSE;
    if (mem_stringmissx) begin
        mem_stringmiss <= `TRUE;
//        dram0_op <= `NOP;   // clears string miss
    end
        ic_invalidate <= `FALSE;
        dc_invalidate <= `FALSE;
        ic_invalidate_line <= `FALSE;
    dc_invalidate_line <= `FALSE;
    alu0_dataready <= `FALSE;
    alu1_dataready <= `FALSE;
 
    // Reset segmentation flag once operating in non-segmented area.
    if (pc[ABW-1:ABW-4]==4'hF)
        pc[ABW] <= 1'b0;
 
    if (rst_i)
        cstate <= RESET1;
        if (rst_i||cstate==RESET1||cstate==RESET2) begin
            imcd <= 6'h3F;
            wb_nack();
`ifdef PCHIST
            pc_cap <= `TRUE;
`endif
            ierr <= 1'b0;
                GM <= 8'hFF;
                nmi_edge <= 1'b0;
                pc <= RSTPC[ABW-1:0];
                StatusHWI <= `TRUE;             // disables interrupts at startup until an RTI instruction is executed.
                im <= 1'b1;
                imb <= 1'b1;
                ic_invalidate <= `TRUE;
                dc_invalidate <= `TRUE;
                fetchbuf <= 1'b0;
                fetchbufA_v <= `INV;
                fetchbufB_v <= `INV;
                fetchbufC_v <= `INV;
                fetchbufD_v <= `INV;
                fetchbufA_instr <= {8{8'h10}};
                fetchbufB_instr <= {8{8'h10}};
                fetchbufC_instr <= {8{8'h10}};
                fetchbufD_instr <= {8{8'h10}};
                fetchbufA_pc <= {{DBW-4{1'b1}},4'h0};
                fetchbufB_pc <= {{DBW-4{1'b1}},4'h0};
                fetchbufC_pc <= {{DBW-4{1'b1}},4'h0};
                fetchbufD_pc <= {{DBW-4{1'b1}},4'h0};
                for (i=0; i< QENTRIES; i=i+1) begin
                        iqentry_v[i] <= `INV;
                        iqentry_agen[i] <= `FALSE;
                        iqentry_op[i] <= `NOP;
                        iqentry_memissue[i] <= `FALSE;
                        iqentry_a1[i] <= 64'd0;
                        iqentry_a2[i] <= 64'd0;
                        iqentry_a3[i] <= 64'd0;
                        iqentry_T[i] <= 64'd0;
                        iqentry_a1_v[i] <= `INV;
                        iqentry_a2_v[i] <= `INV;
                        iqentry_a3_v[i] <= `INV;
                        iqentry_T_v[i] <= `INV;
                        iqentry_a1_s[i] <= 4'd0;
                        iqentry_a2_s[i] <= 4'd0;
                        iqentry_a3_s[i] <= 4'd0;
                        iqentry_T_s[i] <= 4'd0;
                end
                // All the register are flagged as valid on startup even though they
                // may not contain valid data. Otherwise the processor will stall
                // waiting for the registers to become valid. Ideally the registers
                // should be initialized with valid values before use. But who knows
                // what someone will do in boot code and we don't want the processor
                // to stall.
                for (n = 1; n < NREGS; n = n + 1) begin
                        rf_v[n] = `VAL;
`ifdef SIMULATION
                        rf_source[n] <= 4'd0;
`endif
        dbg_ctrl <= {DBW{1'b0}};
`ifdef SIMULATION
        dbg_adr0 <= 0;
        dbg_adr1 <= 0;
        dbg_adr2 <= 0;
        dbg_adr3 <= 0;
`endif
                end
                if (ABW==32)
                  sregs_lmt[7] = 20'hFFFFF;
                else
                  sregs_lmt[7] = 52'hFFFFFFFFFFFFF;
                rf_source[0] <= 4'd0;
//              rf_v[0] = `VAL;
//              rf_v[7'h50] = `VAL;
//              rf_v[7'h5F] = `VAL;
                alu0_available <= `TRUE;
                alu1_available <= `TRUE;
        reset_tail_pointers(1);
                head0 <= 3'd0;
                head1 <= 3'd1;
                head2 <= 3'd2;
                head3 <= 3'd3;
                head4 <= 3'd4;
                head5 <= 3'd5;
                head6 <= 3'd6;
                head7 <= 3'd7;
                dram0 <= 3'b00;
                dram1 <= 3'b00;
                dram2 <= 3'b00;
                tlb_state <= 3'd0;
                panic <= `PANIC_NONE;
                string_pc <= 64'd0;
                // The pc wraps around to address zero while fetching the reset vector.
                // This causes the processor to use the code segement register so the
                // CS has to be defined for reset.
                sregs[7] <= RSTCSEG;
                for (i=0; i < 16; i=i+1)
                        pregs[i] <= 4'd0;
                asid <= 8'h00;
                rrmapno <= 3'd0;
                dram0_id <= 0;
                alu1_sourceid <= 0;
        end
 
        // The following registers are always valid
        rf_v[7'h00] = `VAL;
        rf_v[7'h50] = `VAL;     // C0
        rf_v[7'h5F] = `VAL;     // C15 (PC)
        rf_v[7'h72] = `VAL; // tick
    queued1 = `FALSE;
    queued2 = `FALSE;
    allowq = `TRUE;
    dbg_stat <= dbg_stat | dbg_stat1x;
 
        did_branchback <= take_branch;
        did_branchback0 <= take_branch0;
        did_branchback1 <= take_branch1;
 
`include "Thor_Retarget.v"
/*
        if (branchmiss) begin
                for (n = 1; n < NREGS; n = n + 1)
                        if (rf_v[n] == `INV && ~livetarget[n]) begin
                          $display("brmiss: rf_v[%d] <= VAL",n);
                          rf_v[n] = `VAL;
                        end
 
            if (|iqentry_0_latestID[NREGS:1])   rf_source[ iqentry_tgt[0] ] <= { iqentry_mem[0], 3'd0 };
            if (|iqentry_1_latestID[NREGS:1])   rf_source[ iqentry_tgt[1] ] <= { iqentry_mem[1], 3'd1 };
            if (|iqentry_2_latestID[NREGS:1])   rf_source[ iqentry_tgt[2] ] <= { iqentry_mem[2], 3'd2 };
            if (|iqentry_3_latestID[NREGS:1])   rf_source[ iqentry_tgt[3] ] <= { iqentry_mem[3], 3'd3 };
            if (|iqentry_4_latestID[NREGS:1])   rf_source[ iqentry_tgt[4] ] <= { iqentry_mem[4], 3'd4 };
            if (|iqentry_5_latestID[NREGS:1])   rf_source[ iqentry_tgt[5] ] <= { iqentry_mem[5], 3'd5 };
            if (|iqentry_6_latestID[NREGS:1])   rf_source[ iqentry_tgt[6] ] <= { iqentry_mem[6], 3'd6 };
            if (|iqentry_7_latestID[NREGS:1])   rf_source[ iqentry_tgt[7] ] <= { iqentry_mem[7], 3'd7 };
 
        end
*/
        if (ihit) begin
                $display("\r\n");
                $display("TIME %0d", $time);
        end
 
// COMMIT PHASE (register-file update only ... dequeue is elsewhere)
//
// look at head0 and head1 and let 'em write the register file if they are ready
//
// why is it happening here and not in another phase?
// want to emulate a pass-through register file ... i.e. if we are reading
// out of r3 while writing to r3, the value read is the value written.
// requires BLOCKING assignments, so that we can read from rf[i] later.
//
if (commit0_v) begin
        if (!rf_v[ commit0_tgt ]) begin
            rf_v[ commit0_tgt ] = (rf_source[ commit0_tgt ] == commit0_id) || ((branchmiss) && iqentry_source[ commit0_id[2:0] ]);
        end
        if (commit0_tgt != 7'd0) $display("r%d <- %h", commit0_tgt, commit0_bus);
end
if (commit1_v) begin
        if (!rf_v[ commit1_tgt ]) begin
            rf_v[ commit1_tgt ] = (rf_source[ commit1_tgt ] == commit1_id)|| ((branchmiss) && iqentry_source[ commit1_id[2:0] ]);
        end
        if (commit1_tgt != 7'd0) $display("r%d <- %h", commit1_tgt, commit1_bus);
end
 
// This chunk of code has to be before the enqueue stage so that the agen bit
// can be reset to zero by enqueue.
// put results into the appropriate instruction entries
//
if ((alu0_op==`RR && (alu0_fn==`MUL || alu0_fn==`MULU)) || alu0_op==`MULI || alu0_op==`MULUI) begin
    if (alu0_done) begin
        alu0_dataready <= `TRUE;
    end
end
else if ((alu0_op==`RR && (alu0_fn==`DIV || alu0_fn==`DIVU || alu0_fn==`MOD || alu0_fn==`MODU)) ||
    alu0_op==`DIVI || alu0_op==`DIVUI || alu0_op==`MODI || alu0_op==`MODUI) begin
    if (alu0_done) begin
        alu0_dataready <= `TRUE;
    end
end
 
if (alu0_v) begin
        if (|alu0_exc)
            set_exception(alu0_id,
               alu0_exc==`EXC_PRIV ? 8'd245 :
               alu0_exc==`EXC_DBZ ? 8'd241 :
               alu0_exc==`EXC_CHK ? 8'd239 : 8'h00);
        else begin
        if (iqentry_op[alu0_id[2:0]]!=`IMM)
            iqentry_done[ alu0_id[2:0] ] <= (!iqentry_mem[ alu0_id[2:0] ] || !alu0_cmt);
        if (iqentry_jmpi[alu0_id[2:0]] && alu0_cmt)
            iqentry_res [alu0_id[2:0]] <= alu0_pc + alu0_insnsz;
        else
            iqentry_res [ alu0_id[2:0] ] <= alu0_bus;
        iqentry_out     [ alu0_id[2:0] ] <= `FALSE;
                iqentry_cmt [ alu0_id[2:0] ] <= alu0_cmt;
        iqentry_agen[ alu0_id[2:0] ] <= `TRUE;
        end
end
 
 
if (((alu1_op==`RR && (alu1_fn==`MUL || alu1_fn==`MULU)) || alu1_op==`MULI || alu1_op==`MULUI) && ALU1BIG) begin
    if (alu1_done) begin
        alu1_dataready <= `TRUE;
    end
end
else if (((alu1_op==`RR && (alu1_fn==`DIV || alu1_fn==`DIVU || alu1_fn==`MOD || alu1_fn==`MODU)) ||
    alu1_op==`DIVI || alu1_op==`DIVUI || alu1_op==`MODI || alu1_op==`MODUI) && ALU1BIG) begin
    if (alu1_done) begin
        alu1_dataready <= `TRUE;
    end
end
 
if (alu1_v) begin
        if (|alu1_exc)
            set_exception(alu1_id,
               alu1_exc==`EXC_PRIV ? 8'd245 :
               alu1_exc==`EXC_DBZ ? 8'd241 :
               alu1_exc==`EXC_CHK ? 8'd239 : 8'h00);
        else begin
        if (iqentry_op[alu1_id[2:0]]!=`IMM)
             iqentry_done[ alu1_id[2:0] ] <= (!iqentry_mem[ alu1_id[2:0] ] || !alu1_cmt);
        if (iqentry_jmpi[alu1_id[2:0]] && alu1_cmt)
             iqentry_res [alu1_id[2:0]] <= alu1_pc + alu1_insnsz;
         else
             iqentry_res [ alu1_id[2:0] ] <= alu1_bus;
        iqentry_out     [ alu1_id[2:0] ] <= `FALSE;
                iqentry_cmt [ alu1_id[2:0] ] <= alu1_cmt;
        iqentry_agen[ alu1_id[2:0] ] <= `TRUE;
        end
end
 
`ifdef FLOATING_POINT
if (fp0_v) begin
        $display("0results to iq[%d]=%h", fp0_id[2:0],fp0_bus);
        if (|fp0_exc)
            set_exception(fp0_id, fp0_exc);
        else begin
                iqentry_res     [ fp0_id[2:0] ] <= fp0_bus;
                iqentry_done[ fp0_id[2:0] ] <= fp0_done || !fp0_cmt;
                iqentry_out     [ fp0_id[2:0] ] <= `FALSE;
                iqentry_cmt [ fp0_id[2:0] ] <= fp0_cmt;
                iqentry_agen[ fp0_id[2:0] ] <= `TRUE;
        end
end
`endif
 
//-------------------------------------------------------------------------------
// ENQUEUE
//
// place up to three instructions from the fetch buffer into slots in the IQ.
//   note: they are placed in-order, and they are expected to be executed
// 0, 1, or 2 of the fetch buffers may have valid data
// 0, 1, or 2 slots in the instruction queue may be available.
// if we notice that one of the instructions in the fetch buffer is a predicted
// branch, (set branchback/backpc and delete any instructions after it in
// fetchbuf)
//
// We place the queue logic before the fetch to allow the tools to do the work
// for us. The fetch logic needs to know how many entries were queued, this is
// tracked in the queue stage by variables queued1,queued2,queued3. Blocking
// assignments are used for these vars.
//-------------------------------------------------------------------------------
//
    exception_set = `FALSE;
    queued1 = `FALSE;
    queued2 = `FALSE;
    allowq = `TRUE;
    qstomp = `FALSE;
    if (branchmiss) // don't bother doing anything if there's been a branch miss
        reset_tail_pointers(0);
    else begin
        case ({fetchbuf0_v, fetchbuf1_v && fnNumReadPorts(fetchbuf1_instr) <=  ports_avail})
        2'b00: ; // do nothing
        2'b01:  enque1(tail0,1,0,1);
        2'b10:  enque0(tail0,1,0,1);
        2'b11:  begin
                enque0(tail0,1,1,1);
                if (allowq)
                    enque1(tail1,2,0,0);
                validate_args();
                end
        endcase
    end
 
//------------------------------------------------------------------------------
// FETCH
//
// fetch at least two instructions from memory into the fetch buffer unless
// either one of the buffers is still full, in which case we do nothing (kinda
// like alpha approach)
//------------------------------------------------------------------------------
//
if (branchmiss) begin
    $display("pc <= %h", misspc);
    pc <= misspc;
    fetchbuf <= 1'b0;
    fetchbufA_v <= 1'b0;
    fetchbufB_v <= 1'b0;
    fetchbufC_v <= 1'b0;
    fetchbufD_v <= 1'b0;
end
else if (take_branch) begin
        if (fetchbuf == 1'b0) begin
                case ({fetchbufA_v,fetchbufB_v,fetchbufC_v,fetchbufD_v})
                4'b0000:
                        begin
                            fetchCD();
                                if (do_pcinc) pc[31:0] <= pc[31:0] + fnInsnLength(insn) + fnInsnLength1(insn);
                                fetchbuf <= 1'b1;
                        end
                4'b0100:
                        begin
                            fetchCD();
                                if (do_pcinc) pc[31:0] <= pc[31:0] + fnInsnLength(insn) + fnInsnLength1(insn);
                                fetchbufB_v <= !queued1;
                                if (queued1) begin
                                    fetchbufB_instr <= 64'd0;
                                        fetchbuf <= 1'b1;
                                end
                                if (queued2|queued3)
                                    panic <= `PANIC_INVALIDIQSTATE;
                        end
                4'b0111:
                        begin
                                fetchbufB_v <= !queued1;
                                if (queued1) begin
                                        fetchbuf <= 1'b1;
                                    fetchbufB_instr <= 64'd0;
                                end
                                if (queued2|queued3)
                    panic <= `PANIC_INVALIDIQSTATE;
                        end
                4'b1000:
                        begin
                            fetchCD();
                                if (do_pcinc) pc[31:0] <= pc[31:0] + fnInsnLength(insn) + fnInsnLength1(insn);
                                fetchbufA_v <= !queued1;
                                if (queued1) begin
                                        fetchbuf <= 1'b1;
                                    fetchbufA_instr <= 64'd0;
                                end
                                if (queued2|queued3)
                    panic <= `PANIC_INVALIDIQSTATE;
                        end
                4'b1011:
                        begin
                                fetchbufA_v <= !queued1;
                                if (queued1) begin
                                        fetchbuf <= 1'b1;
                                    fetchbufB_instr <= 64'd0;
                            end
                                if (queued2|queued3)
                    panic <= `PANIC_INVALIDIQSTATE;
                        end
                4'b1100:
                        // Note that there is no point to loading C,D here because
                        // there is a predicted taken branch that would stomp on the
                        // instructions anyways.
                        if ((fnIsBranch(opcodeA) && predict_takenBr)||opcodeA==`LOOP) begin
                                pc <= branch_pc;
                                fetchbufA_v <= !(queued1|queued2);
                                fetchbufB_v <= `INV;            // stomp on it
                                // may as well stick with same fetchbuf
                        end
                        else begin
                                if (did_branchback0) begin
                                    fetchCD();
                                        if (do_pcinc) pc[31:0] <= pc[31:0] + fnInsnLength(insn) + fnInsnLength1(insn);
                                        fetchbufA_v <= !(queued1|queued2);
                                        fetchbufB_v <= !queued2;
                                        if (queued2)
                                                fetchbuf <= 1'b1;
                                end
                                else begin
                                        pc[ABW-1:0] <= branch_pc;
                                        fetchbufA_v <= !(queued1|queued2);
                                        fetchbufB_v <= !queued2;
                                        // may as well keep the same fetchbuffer
                                end
                        end
                4'b1111:
                        begin
                                fetchbufA_v <= !(queued1|queued2);
                                fetchbufB_v <= !queued2;
                                if (queued2) begin
                                        fetchbuf <= 1'b1;
                                    fetchbufA_instr <= 64'd0;
                                    fetchbufB_instr <= 64'd0;
                            end
                        end
                default: panic <= `PANIC_INVALIDFBSTATE;
                endcase
        end
        else begin      // fetchbuf==1'b1
                case ({fetchbufC_v,fetchbufD_v,fetchbufA_v,fetchbufB_v})
                4'b0000:
                        begin
                            fetchAB();
                                if (do_pcinc) pc[31:0] <= pc[31:0] + fnInsnLength(insn) + fnInsnLength1(insn);
                                fetchbuf <= 1'b0;
                        end
                4'b0100:
                        begin
                            fetchAB();
                                if (do_pcinc) pc[31:0] <= pc[31:0] + fnInsnLength(insn) + fnInsnLength1(insn);
                                fetchbufD_v <= !queued1;
                                if (queued1)
                                        fetchbuf <= 1'b0;
                                if (queued2|queued3)
                    panic <= `PANIC_INVALIDIQSTATE;
                        end
                4'b0111:
                        begin
                                fetchbufD_v <= !queued1;
                                if (queued1)
                                        fetchbuf <= 1'b0;
                                if (queued2|queued3)
                    panic <= `PANIC_INVALIDIQSTATE;
                        end
                4'b1000:
                        begin
                            fetchAB();
                                if (do_pcinc) pc[31:0] <= pc[31:0] + fnInsnLength(insn) + fnInsnLength1(insn);
                                fetchbufC_v <= !queued1;
                                if (queued1)
                                        fetchbuf <= 1'b0;
                                if (queued2|queued3)
                    panic <= `PANIC_INVALIDIQSTATE;
                        end
                4'b1011:
                        begin
                                fetchbufC_v <= !queued1;
                                if (queued1)
                                        fetchbuf <= 1'b0;
                                if (queued2|queued3)
                    panic <= `PANIC_INVALIDIQSTATE;
                        end
                4'b1100:
                        if ((fnIsBranch(opcodeC) && predict_takenBr)||opcodeC==`LOOP) begin
                                pc <= branch_pc;
                                fetchbufC_v <= !(queued1|queued2);
                                fetchbufD_v <= `INV;            // stomp on it
                                // may as well stick with same fetchbuf
                        end
                        else begin
                                if (did_branchback1) begin
                                    fetchAB();
                                        if (do_pcinc) pc[31:0] <= pc[31:0] + fnInsnLength(insn) + fnInsnLength1(insn);
                                        fetchbufC_v <= !(queued1|queued2);
                                        fetchbufD_v <= !queued2;
                                        if (queued2)
                                                fetchbuf <= 1'b0;
                                end
                                else begin
                                        pc[ABW-1:0] <= branch_pc;
                                        fetchbufC_v <= !(queued1|queued2);
                                        fetchbufD_v <= !queued2;
                                        // may as well keep the same fetchbuffer
                                end
                        end
                4'b1111:
                        begin
                                fetchbufC_v <= !(queued1|queued2);
                                fetchbufD_v <= !queued2;
                                if (queued2)
                                        fetchbuf <= 1'b0;
                        end
                default: panic <= `PANIC_INVALIDFBSTATE;
                endcase
        end
end
else begin
        if (fetchbuf == 1'b0)
                case ({fetchbufA_v, fetchbufB_v})
                2'b00: ;
                2'b01: begin
                        fetchbufB_v <= !(queued2|queued1);
                        fetchbuf <= queued2|queued1;
                        end
                2'b10: begin
                        fetchbufA_v <= !(queued2|queued1);
                        fetchbuf <= queued2|queued1;
                        end
                2'b11: begin
                        fetchbufA_v <= !(queued1|queued2);
                        fetchbufB_v <= !queued2;
                        fetchbuf <= queued2;
                        end
                endcase
        else
                case ({fetchbufC_v, fetchbufD_v})
                2'b00:    ;
                2'b01: begin
                        fetchbufD_v <= !(queued2|queued1);
                        fetchbuf <= !(queued2|queued1);
                        end
                2'b10: begin
                        fetchbufC_v <= !(queued2|queued1);
                        fetchbuf <= !(queued2|queued1);
                        end
                2'b11: begin
                        fetchbufC_v <= !(queued2|queued1);
                        fetchbufD_v <= !queued2;
                        fetchbuf <= !queued2;
                        end
                endcase
        if (fetchbufA_v == `INV && fetchbufB_v == `INV) begin
            fetchAB();
                if (do_pcinc) pc[31:0] <= pc[31:0] + fnInsnLength(insn) + fnInsnLength1(insn);
                // fetchbuf steering logic correction
                if (fetchbufC_v==`INV && fetchbufD_v==`INV && do_pcinc)
                        fetchbuf <= 1'b0;
                $display("hit %b 1pc <= %h", do_pcinc, pc[31:0] + fnInsnLength(insn) + fnInsnLength1(insn));
        end
        else if (fetchbufC_v == `INV && fetchbufD_v == `INV) begin
            fetchCD();
                if (do_pcinc) pc[31:0] <= pc[31:0] + fnInsnLength(insn) + fnInsnLength1(insn);
                $display("2pc <= %h", pc[31:0] + fnInsnLength(insn) + fnInsnLength1(insn));
        end
end
 
        if (ihit) begin
        $display("%h %h hit0=%b hit1=%b#", spc, pc, hit0, hit1);
        $display("insn=%h", insn);
        $display("%c insn0=%h insn1=%h", nmi_edge ? "*" : " ",insn0, insn1);
        $display("takb=%d br_pc=%h #", take_branch, branch_pc);
        $display("%c%c A: %d %h %h # %d",
            45, fetchbuf?45:62, fetchbufA_v, fetchbufA_instr, fetchbufA_pc, fnInsnLength(fetchbufA_instr));
        $display("%c%c B: %d %h %h # %d",
            45, fetchbuf?45:62, fetchbufB_v, fetchbufB_instr, fetchbufB_pc, fnInsnLength(fetchbufB_instr));
        $display("%c%c C: %d %h %h # %d",
            45, fetchbuf?62:45, fetchbufC_v, fetchbufC_instr, fetchbufC_pc, fnInsnLength(fetchbufC_instr));
        $display("%c%c D: %d %h %h # %d",
            45, fetchbuf?62:45, fetchbufD_v, fetchbufD_instr, fetchbufD_pc, fnInsnLength(fetchbufD_instr));
        $display("fetchbuf=%d",fetchbuf);
        end
 
//      if (ihit) begin
        for (i=0; i<QENTRIES; i=i+1)
            $display("%c%c %d: %c%c%c%c%c%c%c%c %d %c %c%h %d%s %h %h %h %c %o %h %c %o %h %c %o %h %c %o %h #",
                (i[2:0]==head0)?72:46, (i[2:0]==tail0)?84:46, i,
                iqentry_v[i]?"v":"-", iqentry_done[i]?"d":"-",
                iqentry_cmt[i]?"c":"-", iqentry_out[i]?"o":"-", iqentry_bt[i]?"b":"-", iqentry_memissue[i]?"m":"-",
                iqentry_agen[i]?"a":"-", iqentry_issue[i]?"i":"-",
                iqentry_islot[i],
//              ((i==0) ? iqentry_0_islot : (i==1) ? iqentry_1_islot : (i==2) ? iqentry_2_islot : (i==3) ? iqentry_3_islot :
//               (i==4) ? iqentry_4_islot : (i==5) ? iqentry_5_islot : (i==6) ? iqentry_6_islot : iqentry_7_islot),
                 iqentry_stomp[i] ? "s" : "-",
                (fnIsFlowCtrl(iqentry_op[i]) ? 98 : fnIsMem(iqentry_op[i]) ? 109 : 97),
                iqentry_op[i],
                fnRegstr(iqentry_tgt[i]),fnRegstrGrp(iqentry_tgt[i]),
                iqentry_res[i], iqentry_a0[i],
                iqentry_a1[i], iqentry_a1_v[i]?"v":"-", iqentry_a1_s[i],
                iqentry_a2[i], iqentry_a2_v[i]?"v":"-", iqentry_a2_s[i],
                iqentry_a3[i], iqentry_a3_v[i]?"v":"-", iqentry_a3_s[i],
                iqentry_pred[i], iqentry_p_v[i]?"v":"-", iqentry_p_s[i],
                iqentry_pc[i]);
        $display("com0:%c%c %d r%d %h", commit0_v?"v":"-", iqentry_cmt[head0]?"c":"-", commit0_id, commit0_tgt, commit0_bus);
        $display("com1:%c%c %d r%d %h", commit1_v?"v":"-", iqentry_cmt[head1]?"c":"-", commit1_id, commit1_tgt, commit1_bus);
 
//      end
//`include "Thor_dataincoming.v"
// DATAINCOMING
//
// wait for operand/s to appear on alu busses and puts them into 
// the iqentry_a1 and iqentry_a2 slots (if appropriate)
// as well as the appropriate iqentry_res slots (and setting valid bits)
//
//
if (dram_v && iqentry_v[ dram_id[2:0] ] && iqentry_mem[ dram_id[2:0] ] ) begin    // if data for stomped instruction, ignore
        $display("dram results to iq[%d]=%h", dram_id[2:0],dram_bus);
        if (!iqentry_jmpi[dram_id[2:0]])
           iqentry_res  [ dram_id[2:0] ] <= dram_bus;
        // If an exception occurred, stuff an interrupt instruction into the queue
        // slot. The instruction will re-issue as an ALU operation. We can change
        // the queued instruction because it isn't finished yet.
        if (|dram_exc) begin
            set_exception(dram_id,
               dram_exc==`EXC_DBE ? 8'hFB :
               dram_exc==`EXC_DBG ? 8'd243 :
               dram_exc==`EXC_SEGV ? 8'd244 :
               8'hF8);    // F8 = TLBMiss exception 243 = debug
               $stop;
        end
        else begin
            // Note that the predicate was already evaluated to TRUE before the
            // dram operation started.
            iqentry_cmt[dram_id[2:0]] <= `TRUE;
                iqentry_done[ dram_id[2:0] ] <= `TRUE;
                if ((iqentry_op[dram_id[2:0]]==`STS ||
                     iqentry_op[dram_id[2:0]]==`STCMP ||
                     iqentry_op[dram_id[2:0]]==`STMV ||
                     iqentry_op[dram_id[2:0]]==`STFND
                     ) && lc==64'd0) begin
                        string_pc <= 64'd0;
                end
        end
end
 
// What if there's a databus error during the store ?
// set the IQ entry == DONE as soon as the SW is let loose to the memory system
//
if (dram0 == 2'd2 && fnIsStore(dram0_op) && dram0_op != `STS && dram0_op != `STMV && dram0_op != `SWCR) begin
        if ((alu0_v && dram0_id[2:0] == alu0_id[2:0]) || (alu1_v && dram0_id[2:0] == alu1_id[2:0])) panic <= `PANIC_MEMORYRACE;
        iqentry_done[ dram0_id[2:0] ] <= `TRUE;
        iqentry_cmt [ dram0_id[2:0]] <= `TRUE;
        iqentry_out[ dram0_id[2:0] ] <= `FALSE;
end
if (dram1 == 2'd2 && fnIsStore(dram1_op) && dram1_op != `STS && dram1_op != `STMV && dram1_op != `SWCR) begin
        if ((alu0_v && dram1_id[2:0] == alu0_id[2:0]) || (alu1_v && dram1_id[2:0] == alu1_id[2:0])) panic <= `PANIC_MEMORYRACE;
        iqentry_done[ dram1_id[2:0] ] <= `TRUE;
        iqentry_cmt [ dram1_id[2:0]] <= `TRUE;
        iqentry_out[ dram1_id[2:0] ] <= `FALSE;
end
if (dram2 == 2'd2 && fnIsStore(dram2_op) && dram2_op != `STS && dram2_op != `STMV && dram2_op != `SWCR) begin
        if ((alu0_v && dram2_id[2:0] == alu0_id[2:0]) || (alu1_v && dram2_id[2:0] == alu1_id[2:0])) panic <= `PANIC_MEMORYRACE;
        iqentry_done[ dram2_id[2:0] ] <= `TRUE;
        iqentry_cmt [ dram2_id[2:0]] <= `TRUE;
        iqentry_out[ dram2_id[2:0] ] <= `FALSE;
end
 
//
// see if anybody else wants the results ... look at lots of buses:
//  - alu0_bus
//  - alu1_bus
//  - fp0_bus
//  - mem_bus
//  - commit0_bus
//  - commit1_bus
//
 
for (n = 0; n < QENTRIES; n = n + 1)
begin
        if (iqentry_p_v[n] == `INV && iqentry_p_s[n]==alu0_id && iqentry_v[n] == `VAL && alu0_v == `VAL) begin
                iqentry_pred[n] <= alu0nyb[iqentry_preg[n]];
                iqentry_p_v[n] <= `VAL;
        end
        if (iqentry_a1_v[n] == `INV && iqentry_a1_s[n] == alu0_id && iqentry_v[n] == `VAL && alu0_v == `VAL) begin
                iqentry_a1[n] <= alu0_bus;
                iqentry_a1_v[n] <= `VAL;
        end
        if (iqentry_a2_v[n] == `INV && iqentry_a2_s[n] == alu0_id && iqentry_v[n] == `VAL && alu0_v == `VAL) begin
                iqentry_a2[n] <= alu0_bus;
                iqentry_a2_v[n] <= `VAL;
        end
        if (iqentry_a3_v[n] == `INV && iqentry_a3_s[n] == alu0_id && iqentry_v[n] == `VAL && alu0_v == `VAL) begin
                iqentry_a3[n] <= alu0_bus;
                iqentry_a3_v[n] <= `VAL;
        end
        if (iqentry_T_v[n] == `INV && iqentry_T_s[n] == alu0_id && iqentry_v[n] == `VAL && alu0_v == `VAL) begin
        iqentry_T[n] <= alu0_bus;
        iqentry_T_v[n] <= `VAL;
    end
        if (iqentry_p_v[n] == `INV && iqentry_p_s[n] == alu1_id && iqentry_v[n] == `VAL && alu1_v == `VAL) begin
                iqentry_pred[n] <= alu1nyb[iqentry_preg[n]];
                iqentry_p_v[n] <= `VAL;
        end
        if (iqentry_a1_v[n] == `INV && iqentry_a1_s[n] == alu1_id && iqentry_v[n] == `VAL && alu1_v == `VAL) begin
                iqentry_a1[n] <= alu1_bus;
                iqentry_a1_v[n] <= `VAL;
        end
        if (iqentry_a2_v[n] == `INV && iqentry_a2_s[n] == alu1_id && iqentry_v[n] == `VAL && alu1_v == `VAL) begin
                iqentry_a2[n] <= alu1_bus;
                iqentry_a2_v[n] <= `VAL;
        end
        if (iqentry_a3_v[n] == `INV && iqentry_a3_s[n] == alu1_id && iqentry_v[n] == `VAL && alu1_v == `VAL) begin
                iqentry_a3[n] <= alu1_bus;
                iqentry_a3_v[n] <= `VAL;
        end
        if (iqentry_T_v[n] == `INV && iqentry_T_s[n] == alu1_id && iqentry_v[n] == `VAL && alu1_v == `VAL) begin
        iqentry_T[n] <= alu1_bus;
        iqentry_T_v[n] <= `VAL;
    end
`ifdef FLOATING_POINT
/*
        if (iqentry_p_v[n] == `INV && iqentry_p_s[n] == fp0_id && iqentry_v[n] == `VAL && fp0_v == `VAL) begin
                iqentry_pred[n] <= fp0_bus[3:0];
                iqentry_p_v[n] <= `VAL;
        end
*/
        if (iqentry_a1_v[n] == `INV && iqentry_a1_s[n] == fp0_id && iqentry_v[n] == `VAL && fp0_v == `VAL) begin
                iqentry_a1[n] <= fp0_bus;
                iqentry_a1_v[n] <= `VAL;
        end
        if (iqentry_a2_v[n] == `INV && iqentry_a2_s[n] == fp0_id && iqentry_v[n] == `VAL && fp0_v == `VAL) begin
                iqentry_a2[n] <= fp0_bus;
                iqentry_a2_v[n] <= `VAL;
        end
        if (iqentry_a3_v[n] == `INV && iqentry_a3_s[n] == fp0_id && iqentry_v[n] == `VAL && fp0_v == `VAL) begin
                iqentry_a3[n] <= fp0_bus;
                iqentry_a3_v[n] <= `VAL;
        end
        if (iqentry_T_v[n] == `INV && iqentry_T_s[n] == fp0_id && iqentry_v[n] == `VAL && fp0_v == `VAL) begin
        iqentry_T[n] <= fp0_bus;
        iqentry_T_v[n] <= `VAL;
    end
`endif
    // For SWCR
        if (iqentry_p_v[n] == `INV && iqentry_p_s[n]==dram_id && iqentry_v[n] == `VAL && dram_v == `VAL) begin
                iqentry_pred[n] <= dram_bus[3:0];
                iqentry_p_v[n] <= `VAL;
        end
        if (iqentry_a1_v[n] == `INV && iqentry_a1_s[n] == dram_id && iqentry_v[n] == `VAL && dram_v == `VAL) begin
                iqentry_a1[n] <= dram_bus;
                iqentry_a1_v[n] <= `VAL;
        end
        if (iqentry_a2_v[n] == `INV && iqentry_a2_s[n] == dram_id && iqentry_v[n] == `VAL && dram_v == `VAL) begin
                iqentry_a2[n] <= dram_bus;
                iqentry_a2_v[n] <= `VAL;
        end
        if (iqentry_a3_v[n] == `INV && iqentry_a3_s[n] == dram_id && iqentry_v[n] == `VAL && dram_v == `VAL) begin
                iqentry_a3[n] <= dram_bus;
                iqentry_a3_v[n] <= `VAL;
        end
        if (iqentry_T_v[n] == `INV && iqentry_T_s[n] == dram_id && iqentry_v[n] == `VAL && dram_v == `VAL) begin
        iqentry_T[n] <= dram_bus;
        iqentry_T_v[n] <= `VAL;
    end
        if (iqentry_p_v[n] == `INV && iqentry_p_s[n]==commit0_id && iqentry_v[n] == `VAL && commit0_v == `VAL) begin
                iqentry_pred[n] <= cmt0nyb[iqentry_preg[n]];
                iqentry_p_v[n] <= `VAL;
        end
        if (iqentry_a1_v[n] == `INV && iqentry_a1_s[n] == commit0_id && iqentry_v[n] == `VAL && commit0_v == `VAL) begin
                iqentry_a1[n] <= commit0_bus;
                iqentry_a1_v[n] <= `VAL;
        end
        if (iqentry_a2_v[n] == `INV && iqentry_a2_s[n] == commit0_id && iqentry_v[n] == `VAL && commit0_v == `VAL) begin
                iqentry_a2[n] <= commit0_bus;
                iqentry_a2_v[n] <= `VAL;
        end
        if (iqentry_a3_v[n] == `INV && iqentry_a3_s[n] == commit0_id && iqentry_v[n] == `VAL && commit0_v == `VAL) begin
                iqentry_a3[n] <= commit0_bus;
                iqentry_a3_v[n] <= `VAL;
        end
        if (iqentry_T_v[n] == `INV && iqentry_T_s[n] == commit0_id && iqentry_v[n] == `VAL && commit0_v == `VAL) begin
        iqentry_T[n] <= commit0_bus;
        iqentry_T_v[n] <= `VAL;
    end
        if (iqentry_p_v[n] == `INV && iqentry_p_s[n] == commit1_id && iqentry_v[n] == `VAL && commit1_v == `VAL) begin
                iqentry_pred[n] <= cmt1nyb[iqentry_preg[n]];
                iqentry_p_v[n] <= `VAL;
        end
        if (iqentry_a1_v[n] == `INV && iqentry_a1_s[n] == commit1_id && iqentry_v[n] == `VAL && commit1_v == `VAL) begin
                iqentry_a1[n] <= commit1_bus;
                iqentry_a1_v[n] <= `VAL;
        end
        if (iqentry_a2_v[n] == `INV && iqentry_a2_s[n] == commit1_id && iqentry_v[n] == `VAL && commit1_v == `VAL) begin
                iqentry_a2[n] <= commit1_bus;
                iqentry_a2_v[n] <= `VAL;
        end
        if (iqentry_a3_v[n] == `INV && iqentry_a3_s[n] == commit1_id && iqentry_v[n] == `VAL && commit1_v == `VAL) begin
                iqentry_a3[n] <= commit1_bus;
                iqentry_a3_v[n] <= `VAL;
        end
        if (iqentry_T_v[n] == `INV && iqentry_T_s[n] == commit1_id && iqentry_v[n] == `VAL && commit1_v == `VAL) begin
        iqentry_T[n] <= commit1_bus;
        iqentry_T_v[n] <= `VAL;
    end
end
 
//`include "Thor_issue.v"
// ISSUE 
//
// determines what instructions are ready to go, then places them
// in the various ALU queues.  
// also invalidates instructions following a branch-miss BEQ or any JALR (STOMP logic)
//
//alu0_dataready <= alu0_available && alu0_issue;
/*
                        && ((iqentry_issue[0] && iqentry_islot[0] == 4'd0 && !iqentry_stomp[0])
                         || (iqentry_issue[1] && iqentry_islot[1] == 4'd0 && !iqentry_stomp[1])
                         || (iqentry_issue[2] && iqentry_islot[2] == 4'd0 && !iqentry_stomp[2])
                         || (iqentry_issue[3] && iqentry_islot[3] == 4'd0 && !iqentry_stomp[3])
                         || (iqentry_issue[4] && iqentry_islot[4] == 4'd0 && !iqentry_stomp[4])
                         || (iqentry_issue[5] && iqentry_islot[5] == 4'd0 && !iqentry_stomp[5])
                         || (iqentry_issue[6] && iqentry_islot[6] == 4'd0 && !iqentry_stomp[6])
                         || (iqentry_issue[7] && iqentry_islot[7] == 4'd0 && !iqentry_stomp[7]));
*/
//alu1_dataready <= alu1_available && alu1_issue;
/*
                        && ((iqentry_issue[0] && iqentry_islot[0] == 4'd1 && !iqentry_stomp[0])
                         || (iqentry_issue[1] && iqentry_islot[1] == 4'd1 && !iqentry_stomp[1])
                         || (iqentry_issue[2] && iqentry_islot[2] == 4'd1 && !iqentry_stomp[2])
                         || (iqentry_issue[3] && iqentry_islot[3] == 4'd1 && !iqentry_stomp[3])
                         || (iqentry_issue[4] && iqentry_islot[4] == 4'd1 && !iqentry_stomp[4])
                         || (iqentry_issue[5] && iqentry_islot[5] == 4'd1 && !iqentry_stomp[5])
                         || (iqentry_issue[6] && iqentry_islot[6] == 4'd1 && !iqentry_stomp[6])
                         || (iqentry_issue[7] && iqentry_islot[7] == 4'd1 && !iqentry_stomp[7]));
*/
`ifdef FLOATING_POINT
fp0_dataready <= 1'b1
                        && ((iqentry_fpissue[0] && iqentry_islot[0] == 4'd0 && !iqentry_stomp[0])
                         || (iqentry_fpissue[1] && iqentry_islot[1] == 4'd0 && !iqentry_stomp[1])
                         || (iqentry_fpissue[2] && iqentry_islot[2] == 4'd0 && !iqentry_stomp[2])
                         || (iqentry_fpissue[3] && iqentry_islot[3] == 4'd0 && !iqentry_stomp[3])
                         || (iqentry_fpissue[4] && iqentry_islot[4] == 4'd0 && !iqentry_stomp[4])
                         || (iqentry_fpissue[5] && iqentry_islot[5] == 4'd0 && !iqentry_stomp[5])
                         || (iqentry_fpissue[6] && iqentry_islot[6] == 4'd0 && !iqentry_stomp[6])
                         || (iqentry_fpissue[7] && iqentry_islot[7] == 4'd0 && !iqentry_stomp[7]));
`endif
 
for (n = 0; n < QENTRIES; n = n + 1)
begin
        if (iqentry_v[n] && iqentry_stomp[n]) begin
                iqentry_v[n] <= `INV;
                if (dram0_id[2:0] == n[2:0])      dram0 <= `DRAMSLOT_AVAIL;
                if (dram1_id[2:0] == n[2:0])      dram1 <= `DRAMSLOT_AVAIL;
                if (dram2_id[2:0] == n[2:0])      dram2 <= `DRAMSLOT_AVAIL;
        end
        else if (iqentry_issue[n]) begin
                case (iqentry_islot[n])
                2'd0: if (alu0_available) begin
                        alu0_ld <= 1'b1;
                        alu0_sourceid   <= n[3:0];
                        alu0_insnsz <= iqentry_insnsz[n];
                        alu0_op         <= iqentry_op[n];
                        alu0_fn     <= iqentry_fn[n];
                        alu0_cond   <= iqentry_cond[n];
                        alu0_bt         <= iqentry_bt[n];
                        alu0_pc         <= iqentry_pc[n];
                        alu0_pred   <= iqentry_p_v[n] ? iqentry_pred[n] :
                                                        (iqentry_p_s[n] == alu0_id) ? alu0nyb[iqentry_preg[n]] :
                                                        (iqentry_p_s[n] == alu1_id) ? alu1nyb[iqentry_preg[n]] : 4'h0;
                        alu0_argA       <= iqentry_a1_v[n] ? iqentry_a1[n]
                                                : (iqentry_a1_s[n] == alu0_id) ? alu0_bus
                                                : (iqentry_a1_s[n] == alu1_id) ? alu1_bus
                                                : 64'hDEADDEADDEADDEAD;
                        alu0_argB       <= iqentry_a2_v[n] ? iqentry_a2[n]
                                                : (iqentry_a2_s[n] == alu0_id) ? alu0_bus
                                                : (iqentry_a2_s[n] == alu1_id) ? alu1_bus
                                                : 64'hDEADDEADDEADDEAD;
                        alu0_argC       <=
`ifdef SEGMENTATION
                                       ((iqentry_mem[n] && !iqentry_cmpmv[n]) || iqentry_lla[n]) ? {sregs[iqentry_fn[n][5:3]],12'h000} :
`endif
                                       iqentry_a3_v[n] ? iqentry_a3[n]
                                                : (iqentry_a3_s[n] == alu0_id) ? alu0_bus
                                                : (iqentry_a3_s[n] == alu1_id) ? alu1_bus
                                                : 64'hDEADDEADDEADDEAD;
                        alu0_argT       <= iqentry_T_v[n] ? iqentry_T[n]
                        : (iqentry_T_s[n] == alu0_id) ? alu0_bus
                        : (iqentry_T_s[n] == alu1_id) ? alu1_bus
                        : 64'hDEADDEADDEADDEAD;
            alu0_argI   <= iqentry_a0[n];
            alu0_dataready <= fnAluValid(iqentry_op[n],iqentry_fn[n]);
                iqentry_out[n] <= `TRUE;
                        end
                2'd1: if (alu1_available) begin
                        alu1_ld <= 1'b1;
                        alu1_sourceid   <= n[3:0];
                        alu1_insnsz <= iqentry_insnsz[n];
                        alu1_op         <= iqentry_op[n];
                        alu1_fn     <= iqentry_fn[n];
                        alu1_cond   <= iqentry_cond[n];
                        alu1_bt         <= iqentry_bt[n];
                        alu1_pc         <= iqentry_pc[n];
                        alu1_pred   <= iqentry_p_v[n] ? iqentry_pred[n] :
                                                        (iqentry_p_s[n] == alu0_id) ? alu0nyb[iqentry_preg[n]] :
                                                        (iqentry_p_s[n] == alu1_id) ? alu1nyb[iqentry_preg[n]] : 4'h0;
                        alu1_argA       <= iqentry_a1_v[n] ? iqentry_a1[n]
                            : (iqentry_a1_s[n] == alu0_id) ? alu0_bus
                            : (iqentry_a1_s[n] == alu1_id) ? alu1_bus
                            : 64'hDEADDEADDEADDEAD;
                        alu1_argB       <= iqentry_a2_v[n] ? iqentry_a2[n]
                                                : (iqentry_a2_s[n] == alu0_id) ? alu0_bus
                                                : (iqentry_a2_s[n] == alu1_id) ? alu1_bus
                                                : 64'hDEADDEADDEADDEAD;
                        alu1_argC       <=
`ifdef SEGMENTATION
                                       ((iqentry_mem[n] && !iqentry_cmpmv[n]) || iqentry_lla[n]) ? {sregs[iqentry_fn[n][5:3]],12'h000} :
`endif
                                       iqentry_a3_v[n] ? iqentry_a3[n]
                                                : (iqentry_a3_s[n] == alu0_id) ? alu0_bus
                                                : (iqentry_a3_s[n] == alu1_id) ? alu1_bus
                                                : 64'hDEADDEADDEADDEAD;
                        alu1_argT       <= iqentry_T_v[n] ? iqentry_T[n]
                        : (iqentry_T_s[n] == alu0_id) ? alu0_bus
                        : (iqentry_T_s[n] == alu1_id) ? alu1_bus
                        : 64'hDEADDEADDEADDEAD;
            alu1_argI   <= iqentry_a0[n];
            alu1_dataready <= fnAluValid(iqentry_op[n],iqentry_fn[n]);
                iqentry_out[n] <= `TRUE;
                        end
                default: panic <= `PANIC_INVALIDISLOT;
                endcase
//              iqentry_out[n] <= `TRUE;
                // if it is a memory operation, this is the address-generation step ... collect result into arg1
                if (iqentry_mem[n] && !iqentry_tlb[n]) begin
                        iqentry_a1_v[n] <= `INV;
                        iqentry_a1_s[n] <= n[3:0];
                end
        end
end
 
 
`ifdef FLOATING_POINT
for (n = 0; n < QENTRIES; n = n + 1)
begin
        if (iqentry_v[n] && iqentry_stomp[n])
                ;
        else if (iqentry_fpissue[n]) begin
                case (iqentry_fpislot[n])
                2'd0: if (1'b1) begin
                        fp0_ld <= 1'b1;
                        fp0_sourceid    <= n[3:0];
                        fp0_op          <= iqentry_op[n];
                        fp0_fn     <= iqentry_fn[n];
                        fp0_cond   <= iqentry_cond[n];
                        fp0_pred   <= iqentry_p_v[n] ? iqentry_pred[n] :
                                                        (iqentry_p_s[n] == alu0_id) ? alu0nyb[iqentry_preg[n]] :
                                                        (iqentry_p_s[n] == alu1_id) ? alu1nyb[iqentry_preg[n]] : 4'h0;
                        fp0_argA        <= iqentry_a1_v[n] ? iqentry_a1[n]
                            : (iqentry_a1_s[n] == alu0_id) ? alu0_bus
                            : (iqentry_a1_s[n] == alu1_id) ? alu1_bus
                            : 64'hDEADDEADDEADDEAD;
            fp0_argB    <= iqentry_a2_v[n] ? iqentry_a2[n]
                                                : (iqentry_a2_s[n] == alu0_id) ? alu0_bus
                                                : (iqentry_a2_s[n] == alu1_id) ? alu1_bus
                                                : 64'hDEADDEADDEADDEAD;
                        fp0_argC        <= iqentry_a3_v[n] ? iqentry_a3[n]
                                                : (iqentry_a3_s[n] == alu0_id) ? alu0_bus
                                                : (iqentry_a3_s[n] == alu1_id) ? alu1_bus
                                                : 64'hDEADDEADDEADDEAD;
                        fp0_argT        <= iqentry_T_v[n] ? iqentry_T[n]
                        : (iqentry_T_s[n] == alu0_id) ? alu0_bus
                        : (iqentry_T_s[n] == alu1_id) ? alu1_bus
                        : 64'hDEADDEADDEADDEAD;
                        fp0_argI        <= iqentry_a0[n];
                        end
                default: panic <= `PANIC_INVALIDISLOT;
                endcase
                iqentry_out[n] <= `TRUE;
        end
end
`endif
 
// MEMORY
//
// update the memory queues and put data out on bus if appropriate
// Always puts data on the bus even for stores. In the case of
// stores, the data is ignored.
//
//
// dram0, dram1, dram2 are the "state machines" that keep track
// of three pipelined DRAM requests.  if any has the value "00", 
// then it can accept a request (which bumps it up to the value "01"
// at the end of the cycle).  once it hits the value "10" the request
// and the bus is acknowledged the dram request
// is finished and the dram_bus takes the value.  if it is a store, the 
// dram_bus value is not used, but the dram_v value along with the
// dram_id value signals the waiting memq entry that the store is
// completed and the instruction can commit.
//
if (tlb_state != 3'd0 && tlb_state < 3'd3)
        tlb_state <= tlb_state + 3'd1;
if (tlb_state==3'd3) begin
        dram_v <= `TRUE;
        dram_id <= tlb_id;
        dram_tgt <= tlb_tgt;
        dram_exc <= `EXC_NONE;
        dram_bus <= tlb_dato;
        tlb_op <= 4'h0;
        tlb_state <= 3'd0;
end
 
case(dram0)
// The first state is to translate the virtual to physical address.
// Also a good spot to check for debug match and segment limit violation.
3'd1:
        begin
                $display("0MEM %c:%h %h cycle started",fnIsStore(dram0_op)?"S" : "L", dram0_addr, dram0_data);
                if (dbg_lmatch|dbg_smatch) begin
                    dram_v <= `TRUE;
                    dram_id <= dram0_id;
                    dram_tgt <= dram0_tgt;
            dram_exc <= `EXC_DBG;
            dram_bus <= 64'h0;
            dram0 <= 3'd0;
        end
`ifdef SEGMENTATION
`ifdef SEGLIMITS
        else if (dram0_addr[ABW-1:12] >= dram0_lmt) begin
            dram_v <= `TRUE;            // we are finished the memory cycle
            dram_id <= dram0_id;
            dram_tgt <= dram0_tgt;
            dram_exc <= `EXC_SEGV;    //dram0_exc;
            dram_bus <= 64'h0;
            dram0 <= 3'd0;
        end
`endif
`endif
        else if (!cyc_o) dram0 <= dram0 + 3'd1;
        end
 
// State 2:
// Check for a TLB miss on the translated address, and
// Initiate a bus transfer
3'd2:
        if (DTLBMiss) begin
                dram_v <= `TRUE;                        // we are finished the memory cycle
                dram_id <= dram0_id;
                dram_tgt <= dram0_tgt;
                dram_exc <= `EXC_TLBMISS;       //dram0_exc;
                dram_bus <= 64'h0;
                dram0 <= 3'd0;
        end
        else if (dram0_exc!=`EXC_NONE) begin
                dram_v <= `TRUE;                        // we are finished the memory cycle
        dram_id <= dram0_id;
        dram_tgt <= dram0_tgt;
        dram_exc <= dram0_exc;
                dram_bus <= 64'h0;
        dram0 <= 3'd0;
        end
        else begin
            if (dram0_op==`LCL) begin
               if (dram0_tgt==7'd0) begin
                   ic_invalidate_line <= `TRUE;
                   ic_lineno <= dram0_addr;
               end
           dram0 <= 3'd6;
            end
                else if (uncached || fnIsStore(dram0_op) || fnIsLoadV(dram0_op) || dram0_op==`CAS ||
                  ((dram0_op==`STMV || dram0_op==`INC) && stmv_flag)) begin
                if (cstate==IDLE) begin // make sure an instruction load isn't taking place
                dram0_owns_bus <= `TRUE;
                resv_o <= dram0_op==`LVWAR;
                cres_o <= dram0_op==`SWCR;
                lock_o <= dram0_op==`CAS;
                cyc_o <= 1'b1;
                stb_o <= 1'b1;
                we_o <= fnIsStore(dram0_op) || ((dram0_op==`STMV || dram0_op==`INC) && stmv_flag);
                sel_o <= fnSelect(dram0_op,dram0_fn,pea);
                rsel <= fnSelect(dram0_op,dram0_fn,pea);
                adr_o <= pea;
                if (dram0_op==`INC)
                    dat_o <= fnDatao(dram0_op,dram0_fn,dram0_data) + index;
                else
                    dat_o <= fnDatao(dram0_op,dram0_fn,dram0_data);
                dram0 <= dram0 + 3'd1;
                        end
                end
                else begin      // cached read
                        dram0 <= 3'd6;
            rsel <= fnSelect(dram0_op,dram0_fn,pea);
           end
        end
 
// State 3:
// Wait for a memory ack
3'd3:
        if (ack_i|err_i) begin
                $display("MEM ack");
                dram_v <= dram0_op != `CAS && dram0_op != `INC && dram0_op != `STS && dram0_op != `STMV && dram0_op != `STCMP && dram0_op != `STFND;
                dram_id <= dram0_id;
                dram_tgt <= dram0_tgt;
                dram_exc <= (err_i & dram0_tgt!=7'd0) ? `EXC_DBE : `EXC_NONE;//dram0_exc;
                if (dram0_op==`SWCR)
                     dram_bus <= {63'd0,resv_i};
                else
                     dram_bus <= fnDatai(dram0_op,dram0_fn,dat_i[DBW-1:0],rsel);
                dram0_owns_bus <= `FALSE;
                wb_nack();
        dram0 <= 3'd7;
                case(dram0_op)
`ifdef STRINGOPS
                `STS:
                        if (lc != 0 && !int_pending) begin
                                dram0_addr <= dram0_addr + fnIndexAmt(dram0_fn);
                                lc <= lc - 64'd1;
                                dram0 <= 3'd1;
//                              dram_bus <= dram0_addr + fnIndexAmt(dram0_fn) - dram0_seg;
            end
            else begin
                dram_bus <= dram0_addr + fnIndexAmt(dram0_fn) - dram0_seg;
                dram_v <= `VAL;
                dram0_op <= `NOP;
            end
        `STMV,`STCMP:
            begin
                dram_bus <= index;
                if (lc != 0 && !(int_pending && stmv_flag)) begin
                    dram0 <= 3'd1;
                    dram0_owns_bus <= `TRUE;
                    if (stmv_flag) begin
                        dram0_addr <= src_addr + index;
                        if (dram0_op==`STCMP) begin
                            if (dram0_data != fnDatai(dram0_op,dram0_fn,dat_i[DBW-1:0],rsel)) begin
                                lc <= 64'd0;
                                dram0 <= 3'd7;
                                dram_v <= `VAL;
                            end
                        end
                    end
                    else begin
                        dram0_addr <= dst_addr + index;
                        dram0_data <= fnDatai(dram0_op,dram0_fn,dat_i[DBW-1:0],rsel);
                    end
                    if (!stmv_flag)
                        inc_index(dram0_fn);
                    stmv_flag <= ~stmv_flag;
                end
                else begin
                    dram_v <= `VAL;
                    dram0_op <= `NOP;
                end
            end
        `STFND:
            if (lc != 0 && !int_pending) begin
                dram0_addr <= src_addr + index;
                inc_index(dram0_fn);
                if (dram0_data == fnDatai(dram0_op,dram0_fn,dat_i[DBW-1:0],rsel)) begin
                    lc <= 64'd0;
                    dram_v <= `VAL;
                    dram_bus <= index;
                end
                else
                    dram0 <= 3'd1;
            end
            else begin
                dram_bus <= index;
                dram_v <= `VAL;
                dram0_op <= `NOP;
            end
`endif
        `CAS:
                        if (dram0_datacmp == dat_i[DBW-1:0]) begin
                                $display("CAS match");
                                dram0_owns_bus <= `TRUE;
                                cyc_o <= 1'b1;  // hold onto cyc_o
                                dram0 <= dram0 + 3'd1;
                        end
                        else begin
                                dram_v <= `VAL;
                                dram0 <= 3'd0;
                    end
                `INC:
                     begin
                         if (stmv_flag) begin
                             dram_v <= `VAL;
                                 dram0 <= 3'd0;
                         end
                         else begin
                             dram0_data <= fnDatai(dram0_op,dram0_fn,dat_i[DBW-1:0],rsel);
                     stmv_flag <= ~stmv_flag;
                     dram0 <= 3'd1;
                         end
                     end
                `NOP:
                      begin
                      dram_v <= `VAL;
                  dram0 <= 3'd0;
                      end
                default:  ;
                endcase
        end
 
// State 4:
// Start a second bus transaction for the CAS instruction
3'd4:
        begin
                stb_o <= 1'b1;
                we_o <= 1'b1;
                sel_o <= fnSelect(dram0_op,dram0_fn,pea);
                adr_o <= pea;
                dat_o <= fnDatao(dram0_op,dram0_fn,dram0_data);
                dram0 <= dram0 + 3'd1;
        end
 
// State 5:
// Wait for a memory ack for the second bus transaction of a CAS
//
3'd5:
    begin
        dram_id <= dram0_id;
        dram_tgt <= dram0_tgt;
        if (ack_i|err_i) begin
            $display("MEM ack2");
            dram_v <= `VAL;
            dram_exc <= (err_i & dram0_tgt!=7'd0) ? `EXC_DBE : `EXC_NONE;
            dram0_owns_bus <= `FALSE;
            wb_nack();
            lock_o <= 1'b0;
            dram0 <= 3'd7;
        end
    end
 
// State 6:
// Wait for a data cache read hit
3'd6:
        if (rhit && dram0_op!=`LCL) begin
            case(dram0_op)
`ifdef STRINGOPS
            // The read portion of the STMV was just done, go back and do
            // the write portion.
        `STMV:
           begin
               stmv_flag <= `TRUE;
               dram0_addr <= dst_addr + index;
               dram0_data <= fnDatai(dram0_op,dram0_fn,cdat,rsel);
               dram0 <= 3'd1;
           end
        `STCMP:
            begin
                dram_bus <= index;
                dram_id <= dram0_id;
                dram_tgt <= dram0_tgt;
                if (lc != 0 && !int_pending && stmv_flag) begin
                    dram0_addr <= src_addr + index;
                    stmv_flag <= ~stmv_flag;
                    $display("*****************************");
                    $display("STCMP READ2:%H",fnDatai(dram0_op,dram0_fn,cdat,rsel));
                    $display("*****************************");
                    if (dram0_data != fnDatai(dram0_op,dram0_fn,cdat,rsel)) begin
                        lc <= 64'd0;
                        dram0 <= 3'd7;
                        dram_v <= `VAL;
                    end
                end
                else if (!stmv_flag) begin
                    stmv_flag <= ~stmv_flag;
                    dram0_addr <= dst_addr + index;
                    dram0_data <= fnDatai(dram0_op,dram0_fn,cdat,rsel);
                    $display("*****************************");
                    $display("STCMP READ1:%H",fnDatai(dram0_op,dram0_fn,cdat,rsel));
                    $display("*****************************");
                    dram0 <= 3'd1;
                    inc_index(dram0_fn);
                end
                else begin
                    dram_v <= `VAL;
                    dram0 <= 3'd7;
                    dram0_op <= `NOP;
                end
            end
        `STFND:
            begin
                dram_id <= dram0_id;
                dram_tgt <= dram0_tgt;
                dram_bus <= index;
                if (lc != 0 && !int_pending) begin
                    dram0 <= 3'd1;
                    dram0_addr <= src_addr + index;
                    inc_index(dram0_fn);
                    if (dram0_data == fnDatai(dram0_op,dram0_fn,cdat,rsel)) begin
                        lc <= 64'd0;
                        dram0 <= 3'd7;
                        dram_v <= `VAL;
                    end
                end
                else begin
                    dram_v <= `VAL;
                    dram0 <= 3'd7;
                    dram0_op <= `NOP;
                end
            end
`endif
                `INC:
             begin
                 dram0_data <= fnDatai(dram0_op,dram0_fn,cdat,rsel);
                 stmv_flag <= `TRUE;
                 dram0 <= 3'd1;
            end
        // Set to NOP on a string miss
        `NOP:   begin
                dram_v <= `VAL;
                dram0 <= 3'd0;
                end
    default: begin
            $display("Read hit [%h]",dram0_addr);
            dram_v <= `TRUE;
            dram_id <= dram0_id;
            dram_tgt <= dram0_tgt;
            dram_exc <= `EXC_NONE;
            dram_bus <= fnDatai(dram0_op,dram0_fn,cdat,rsel);
            dram0 <= 3'd0;
            end
        endcase
        end
3'd7:
    begin
    dram0 <= 3'd0;
    end
default:    dram0 <= 3'd0;
endcase
 
//
// determine if the instructions ready to issue can, in fact, issue.
// "ready" means that the instruction has valid operands but has not gone yet
//
// Stores can only issue if there is no possibility of a change of program flow.
// That means no flow control operations or instructions that can cause an
// exception can be before the store.
iqentry_memissue[ head0 ] <= iqentry_memissue_head0;
iqentry_memissue[ head1 ] <= iqentry_memissue_head1;
iqentry_memissue[ head2 ] <= iqentry_memissue_head2;
iqentry_memissue[ head3 ] <= iqentry_memissue_head3;
iqentry_memissue[ head4 ] <= iqentry_memissue_head4;
iqentry_memissue[ head5 ] <= iqentry_memissue_head5;
iqentry_memissue[ head6 ] <= iqentry_memissue_head6;
iqentry_memissue[ head7 ] <= iqentry_memissue_head7;
 
                                /* ||
                                        (   !fnIsFlowCtrl(iqentry_op[head0])
                                         && !fnIsFlowCtrl(iqentry_op[head1])
                                         && !fnIsFlowCtrl(iqentry_op[head2])
                                         && !fnIsFlowCtrl(iqentry_op[head3])
                                         && !fnIsFlowCtrl(iqentry_op[head4])
                                         && !fnIsFlowCtrl(iqentry_op[head5])
                                         && !fnIsFlowCtrl(iqentry_op[head6])));
*/
//
// take requests that are ready and put them into DRAM slots
 
if (dram0 == `DRAMSLOT_AVAIL)   dram0_exc <= `EXC_NONE;
 
// Memory should also wait until segment registers are valid. The segment
// registers are essentially static registers while a program runs. They are
// setup by only the operating system. The system software must ensure the
// segment registers are stable before they get used. We don't bother checking
// for rf_v[].
//
for (n = 0; n < QENTRIES; n = n + 1)
        if (!iqentry_stomp[n] && iqentry_memissue[n] && iqentry_agen[n] && iqentry_tlb[n] && !iqentry_out[n]) begin
            $display("TLB issue");
            if (!iqentry_cmt[n]) begin
                iqentry_done[n] <= `TRUE;
                iqentry_out[n] <= `FALSE;
                iqentry_agen[n] <= `FALSE;
                iqentry_res[n] <= iqentry_T_v[n] ? iqentry_T[n]
                        : (iqentry_T_s[n] == alu0_id) ? alu0_bus
                        : (iqentry_T_s[n] == alu1_id) ? alu1_bus
                        : 64'hDEADDEADDEADDEAD;
            end
                else if (tlb_state==3'd0) begin
                        tlb_state <= 3'd1;
                        tlb_id <= {1'b1, n[2:0]};
                        tlb_op <= iqentry_a0[n][3:0];
                        tlb_regno <= iqentry_a0[n][7:4];
                        tlb_tgt <= iqentry_tgt[n];
                        tlb_data <= iqentry_a1[n];
                        iqentry_out[n] <= `TRUE;
                end
        end
        else if (!iqentry_stomp[n] && iqentry_memissue[n] && iqentry_agen[n] && !iqentry_out[n]) begin
            if (!iqentry_cmt[n]) begin
            iqentry_done[n] <= `TRUE;
            iqentry_out[n] <= `FALSE;
            iqentry_agen[n] <= `FALSE;
                iqentry_res[n] <= iqentry_T_v[n] ? iqentry_T[n]
                        : (iqentry_T_s[n] == alu0_id) ? alu0_bus
                        : (iqentry_T_s[n] == alu1_id) ? alu1_bus
                        : 64'hDEADDEADDEADDEAD;
        end
        else begin
            if (fnIsStoreString(iqentry_op[n]))
                string_pc <= iqentry_pc[n];
            $display("issued memory cycle");
            if (dram0 == `DRAMSLOT_AVAIL) begin
                dram0           <= 3'd1;
                dram0_id        <= { 1'b1, n[2:0] };
                dram0_misspc <= iqentry_pc[n];
                dram0_op        <= iqentry_op[n];
                dram0_fn    <= iqentry_fn[n];
                dram0_tgt       <= iqentry_tgt[n];
                dram0_data      <= (iqentry_ndx[n] || iqentry_cas[n]) ? iqentry_a3[n] :
`ifdef STACKOPS
                                iqentry_pea[n] ? iqentry_a2[n] + iqentry_a0[n] :
`endif
                                iqentry_a2[n];
                dram0_datacmp <= iqentry_a2[n];
`ifdef SEGMENTATION
                if (iqentry_cmpmv[n])
                    dram0_addr <= iqentry_a1[n] + {sregs[iqentry_fn[n][5:3]],12'h000};
                else
                    dram0_addr <= iqentry_a1[n];
                dram0_seg <= {sregs[iqentry_fn[n][5:3]],12'h000};
                dram0_lmt <= sregs[iqentry_fn[n][5:3]] + sregs_lmt[iqentry_fn[n][5:3]];
//                dram0_exc <= (iqentry_a1[n][ABW-1:12] >= sregs_lmt[iqentry_fn[n][5:3]]) ? `EXC_SEGV : `EXC_NONE;
`ifdef STRINGOPS
                src_addr <= iqentry_a1[n] + {sregs[iqentry_fn[n][5:3]],12'h000};
                dst_addr <= iqentry_a2[n] + {sregs[iqentry_fn[n][5:3]],12'h000};
`endif
`else
                dram0_addr <= iqentry_a1[n];
`ifdef STRINGOPS
                src_addr <= iqentry_a1[n];
                dst_addr <= iqentry_a2[n];
`endif
`endif
                stmv_flag <= `FALSE;
                index <= iqentry_op[n]==`STS ? fnIndexAmt(iqentry_fn[n]) : iqentry_op[n]==`INC ? iqentry_a2[n] : iqentry_a3[n];
                iqentry_out[n]  <= `TRUE;
            end
                end
        end
 
for (n = 0; n < QENTRIES; n = n + 1)
begin
    if (iqentry_op[n]==`IMM && iqentry_v[(n+1)&7] &&
        ((iqentry_pc[(n+1)&7]==iqentry_pc[n]+iqentry_insnsz[n]) ||
         (iqentry_pc[(n+1)&7]==iqentry_pc[n]))) // address inherited due to interrupt
        iqentry_done[n] <= `TRUE;
    if (!iqentry_v[n])
        iqentry_done[n] <= `FALSE;
end
 
 
//      $display("TLB: en=%b imatch=%b pgsz=%d pcs=%h phys=%h", utlb1.TLBenabled,utlb1.IMatch,utlb1.PageSize,utlb1.pcs,utlb1.IPFN);
//      for (i = 0; i < 64; i = i + 1)
//              $display("vp=%h G=%b",utlb1.TLBVirtPage[i],utlb1.TLBG[i]);
//`include "Thor_commit.v"
// It didn't work in simulation when the following was declared under an
// independant always clk block
//
commit_spr(commit0_v,commit0_tgt,commit0_bus,0);
commit_spr(commit1_v,commit1_tgt,commit1_bus,1);
 
// When the INT instruction commits set the hardware interrupt status to disable further interrupts.
if (int_commit)
begin
        $display("*********************");
        $display("*********************");
        $display("Interrupt committing");
        $display("*********************");
        $display("*********************");
        StatusHWI <= `TRUE;
        imb <= im;
        im <= 1'b0;
        // Reset the nmi edge sense circuit but only for an NMI
        if ((iqentry_a0[head0][7:0]==8'hFE && commit0_v && iqentry_op[head0]==`INT) ||
            (iqentry_a0[head1][7:0]==8'hFE && commit1_v && iqentry_op[head1]==`INT))
                nmi_edge <= 1'b0;
        string_pc <= 64'd0;
`ifdef PCHIST
        pc_cap <= `FALSE;
`endif
end
 
if (sys_commit)
begin
        if (StatusEXL!=8'hFF)
                StatusEXL <= StatusEXL + 8'd1;
end
 
// On a debug commit set status StatusDBG to prevent further single stepping.
`ifdef DEBUG_LOGIC
if (dbg_commit)
begin
    StatusDBG <= `TRUE;
end
`endif
 
oddball_commit(commit0_v,head0);
oddball_commit(commit1_v,head1);
 
//
// COMMIT PHASE (dequeue only ... not register-file update)
//
// If the third instruction is invalidated or if it doesn't update the register
// file then it is allowed to commit too.
// The head pointer might advance by three.
//
if (~|panic)
casex ({ iqentry_v[head0],
        iqentry_done[head0],
        iqentry_v[head1],
        iqentry_done[head1],
        iqentry_v[head2],
        iqentry_done[head2]})
 
        // retire 3
        6'b0x_0x_0x:
                if (head0 != tail0 && head1 != tail0 && head2 != tail0) begin
                    head_inc(3);
                end
                else if (head0 != tail0 && head1 != tail0) begin
                    head_inc(2);
                end
                else if (head0 != tail0) begin
                    head_inc(1);
                end
 
        // retire 2 (wait for regfile for head2)
        6'b0x_0x_10:
                begin
                    head_inc(2);
                end
 
        // retire 2 or 3 (wait for regfile for head2)
        6'b0x_0x_11:
           begin
                if (iqentry_tgt[head2]==7'd0) begin
                    iqentry_v[head2] <= `INV;
                    head_inc(3);
                end
                else begin
                    head_inc(2);
                        end
                end
 
        // retire 3
        6'b0x_11_0x:
                if (head1 != tail0 && head2 != tail0) begin
                        iqentry_v[head1] <= `INV;
                        head_inc(3);
                end
                else begin
                        iqentry_v[head1] <= `INV;
                        head_inc(2);
                end
 
        // retire 2     (wait on head2 or wait on register file for head2)
        6'b0x_11_10:
                begin
                        iqentry_v[head1] <= `INV;
                        head_inc(2);
                end
        6'b0x_11_11:
        begin
            if (iqentry_tgt[head2]==7'd0) begin
                iqentry_v[head1] <= `INV;
                iqentry_v[head2] <= `INV;
                head_inc(3);
            end
            else begin
                iqentry_v[head1] <= `INV;
                head_inc(2);
            end
        end
 
        // 4'b00_00     - neither valid; skip both
        // 4'b00_01     - neither valid; skip both
        // 4'b00_10     - skip head0, wait on head1
        // 4'b00_11     - skip head0, commit head1
        // 4'b01_00     - neither valid; skip both
        // 4'b01_01     - neither valid; skip both
        // 4'b01_10     - skip head0, wait on head1
        // 4'b01_11     - skip head0, commit head1
        // 4'b10_00     - wait on head0
        // 4'b10_01     - wait on head0
        // 4'b10_10     - wait on head0
        // 4'b10_11     - wait on head0
        // 4'b11_00     - commit head0, skip head1
        // 4'b11_01     - commit head0, skip head1
        // 4'b11_10     - commit head0, wait on head1
        // 4'b11_11     - commit head0, commit head1
 
        //
        // retire 0 (stuck on head0)
        6'b10_xx_xx:    ;
 
        // retire 3
        6'b11_0x_0x:
                if (head1 != tail0 && head2 != tail0) begin
                        iqentry_v[head0] <= `INV;
                        head_inc(3);
                end
                else if (head1 != tail0) begin
                        iqentry_v[head0] <= `INV;
                        head_inc(2);
                end
                else begin
                        iqentry_v[head0] <= `INV;
                        head_inc(1);
                end
 
        // retire 2 (wait for regfile for head2)
        6'b11_0x_10:
                begin
                        iqentry_v[head0] <= `INV;
                        head_inc(2);
                end
 
        // retire 2 or 3 (wait for regfile for head2)
        6'b11_0x_11:
            if (iqentry_tgt[head2]==7'd0) begin
                        iqentry_v[head0] <= `INV;
                        iqentry_v[head2] <= `INV;
                        head_inc(3);
            end
            else begin
                        iqentry_v[head0] <= `INV;
                        head_inc(2);
                end
 
        //
        // retire 1 (stuck on head1)
        6'b00_10_xx,
        6'b01_10_xx,
        6'b11_10_xx:
                if (iqentry_v[head0] || head0 != tail0) begin
            iqentry_v[head0] <= `INV;
            head_inc(1);
                end
 
        // retire 2 or 3
        6'b11_11_0x:
                if (head2 != tail0) begin
                        iqentry_v[head0] <= `INV;       // may conflict with STOMP, but since both are setting to 0, it is okay
                        iqentry_v[head1] <= `INV;
                        head_inc(3);
                end
                else begin
                        iqentry_v[head0] <= `INV;
                        iqentry_v[head1] <= `INV;
                        head_inc(2);
                end
 
        // retire 2 (wait on regfile for head2)
        6'b11_11_10:
                begin
                        iqentry_v[head0] <= `INV;       // may conflict with STOMP, but since both are setting to 0, it is okay
                        iqentry_v[head1] <= `INV;       // may conflict with STOMP, but since both are setting to 0, it is okay
                        head_inc(2);
                end
        6'b11_11_11:
            if (iqentry_tgt[head2]==7'd0) begin
            iqentry_v[head0] <= `INV;    // may conflict with STOMP, but since both are setting to 0, it is okay
            iqentry_v[head1] <= `INV;    // may conflict with STOMP, but since both are setting to 0, it is okay
            iqentry_v[head2] <= `INV;    // may conflict with STOMP, but since both are setting to 0, it is okay
            head_inc(3);
            end
        else begin
            iqentry_v[head0] <= `INV;    // may conflict with STOMP, but since both are setting to 0, it is okay
            iqentry_v[head1] <= `INV;    // may conflict with STOMP, but since both are setting to 0, it is okay
            head_inc(2);
        end
endcase
 
        if (branchmiss)
                rrmapno <= iqentry_renmapno[missid];
 
        case(cstate)
        RESET1:
           begin
               ic_ld <= `TRUE;
               ic_ld_cntr <= 32'd0;
               cstate <= RESET2;
           end
        RESET2:
           begin
               ic_ld_cntr <= ic_ld_cntr + 32'd32;
               if (ic_ld_cntr >= 32'd32768) begin
                   ic_ld <= `FALSE;
                   ic_ld_cntr <= 32'd0;
                   cstate <= IDLE;
               end;
           end
        IDLE:
                if (dcache_access_pending) begin
                                $display("********************");
                                $display("DCache access to: %h",{pea[DBW-1:5],5'b00000});
                                $display("********************");
                                derr <= 1'b0;
                                bte_o <= 2'b00;
                                cti_o <= 3'b001;
                                bl_o <= DBW==32 ? 5'd7 : 5'd3;
                                cyc_o <= 1'b1;
                                stb_o <= 1'b1;
                                we_o <= 1'b0;
                                sel_o <= {DBW/8{1'b1}};
                                adr_o <= {pea[DBW-1:5],5'b00000};
                                dat_o <= {DBW{1'b0}};
                                cstate <= DCACHE1;
                end
                else if ((!ihit && !mem_issue && dram0==3'd0)||(dram0==3'd6 && (dram0_op==`LCL && dram0_tgt==7'd0))) begin
                        if ((dram0!=2'd0 || dram1!=2'd0 || dram2!=2'd0) && !(dram0==3'd6 && (dram0_op==`LCL && dram0_tgt==7'd0)))
                                $display("drams non-zero");
                        else begin
                                $display("********************");
                                $display("ICache access to: %h",
                                    (dram0==3'd6 && (dram0_op==`LCL && dram0_tgt==7'd0)) ? {dram0_addr[ABW-1:5],5'h00} :
                                    !hit0 ? {ppc[DBW-1:5],5'b00000} : {ppcp16[DBW-1:5],5'b00000});
                                $display("********************");
                                ierr <= 1'b0;
                                bte_o <= 2'b00;
                                cti_o <= 3'b001;
                                bl_o <= DBW==32 ? 5'd7 : 5'd3;
                                cyc_o <= 1'b1;
                                stb_o <= 1'b1;
                                we_o <= 1'b0;
                                sel_o <= {DBW/8{1'b1}};
                                adr_o <= (dram0==3'd6 && (dram0_op==`LCL && dram0_tgt==7'd0)) ? {dram0_addr[ABW-1:5],5'h00} : !hit0 ? {ppc[DBW-1:5],5'b00000} : {ppcp16[DBW-1:5],5'b00000};
                                dat_o <= {DBW{1'b0}};
                                cstate <= ICACHE1;
                        end
                end
        ICACHE1:
                begin
                        if (ack_i|err_i) begin
                                ierr <= ierr | err_i;   // cumulate an error status
                                if (DBW==32) begin
                                        adr_o[4:2] <= adr_o[4:2] + 3'd1;
                                        if (adr_o[4:2]==3'b110)
                                                cti_o <= 3'b111;
                                        if (adr_o[4:2]==3'b111) begin
                                                wb_nack();
                                                cstate <= IDLE;
                                                if (dram0==3'd6 && dram0_op==`LCL) begin
                                                     dram0_op<=`NOP;
                                                end
                                        end
                                end
                                else begin
                                        adr_o[4:3] <= adr_o[4:3] + 2'd1;
                                        if (adr_o[4:3]==2'b10)
                                                cti_o <= 3'b111;
                                        if (adr_o[4:3]==2'b11) begin
                                                wb_nack();
                                                cstate <= IDLE;
                                                if (dram0==3'd6 && dram0_op==`LCL) begin
                             dram0_op<=`NOP;
                        end
                                        end
                                end
                        end
                end
        DCACHE1:
                begin
                        if (ack_i|err_i) begin
                                derr <= derr | err_i;   // cumulate an error status
                                if (DBW==32) begin
                                        adr_o[4:2] <= adr_o[4:2] + 3'd1;
                                        if (adr_o[4:2]==3'b110)
                                                cti_o <= 3'b111;
                                        if (adr_o[4:2]==3'b111) begin
                                                wb_nack();
                                                cstate <= IDLE;
                                                if (dram0_op==`LCL) begin
                                                    dram0_op <= `NOP;
                                                    dram0_tgt <= 7'd0;
                                                end
                                        end
                                end
                                else begin
                                        adr_o[4:3] <= adr_o[4:3] + 2'd1;
                                        if (adr_o[4:3]==2'b10)
                                                cti_o <= 3'b111;
                                        if (adr_o[4:3]==2'b11) begin
                                                wb_nack();
                                                cstate <= IDLE;
                                                if (dram0_op==`LCL) begin
                                                    dram0_op <= `NOP;
                                                    dram0_tgt <= 7'd0;
                                            end
                                        end
                                end
                        end
                end
    default:    cstate <= IDLE;
        endcase
 
//      for (i=0; i<8; i=i+1)
//          $display("%d: %h %d %o #", i, urf1.regs0[i], rf_v[i], rf_source[i]);
 
        if (ihit) begin
        $display("dr=%d I=%h A=%h B=%h op=%c%d bt=%d src=%o pc=%h #",
                alu0_dataready, alu0_argI, alu0_argA, alu0_argB,
                 (fnIsFlowCtrl(alu0_op) ? 98 : (fnIsMem(alu0_op)) ? 109 : 97),
                alu0_op, alu0_bt, alu0_sourceid, alu0_pc);
        $display("dr=%d I=%h A=%h B=%h op=%c%d bt=%d src=%o pc=%h #",
                alu1_dataready, alu1_argI, alu1_argA, alu1_argB,
                 (fnIsFlowCtrl(alu1_op) ? 98 : (fnIsMem(alu1_op)) ? 109 : 97),
                alu1_op, alu1_bt, alu1_sourceid, alu1_pc);
        $display("v=%d bus=%h id=%o 0 #", alu0_v, alu0_bus, alu0_id);
        $display("bmiss0=%b src=%o mpc=%h #", alu0_branchmiss, alu0_sourceid, alu0_misspc);
        $display("cmt=%b cnd=%d prd=%d", alu0_cmt, alu0_cond, alu0_pred);
        $display("bmiss1=%b src=%o mpc=%h #", alu1_branchmiss, alu1_sourceid, alu1_misspc);
        $display("cmt=%b cnd=%d prd=%d", alu1_cmt, alu1_cond, alu1_pred);
        $display("bmiss=%b mpc=%h", branchmiss, misspc);
 
        $display("0: %d %h %o 0%d #", commit0_v, commit0_bus, commit0_id, commit0_tgt);
        $display("1: %d %h %o 0%d #", commit1_v, commit1_bus, commit1_id, commit1_tgt);
        end
        if (|panic) begin
            $display("");
            $display("-----------------------------------------------------------------");
            $display("-----------------------------------------------------------------");
            $display("---------------     PANIC:%s     -----------------", message[panic]);
            $display("-----------------------------------------------------------------");
            $display("-----------------------------------------------------------------");
            $display("");
            $display("instructions committed: %d", I);
            $display("total execution cycles: %d", $time / 10);
            $display("");
        end
        if (|panic && ~outstanding_stores) begin
            $finish;
        end
end
 
task wb_nack;
begin
    resv_o <= 1'b0;
    cres_o <= 1'b0;
        bte_o <= 2'b00;
        cti_o <= 3'b000;
        bl_o <= 5'd0;
        cyc_o <= 1'b0;
        stb_o <= 1'b0;
        we_o <= 1'b0;
        sel_o <= 8'h00;
        adr_o <= {DBW{1'b0}};
        dat_o <= {DBW{1'b0}};
end
endtask
 
task commit_spr;
input commit_v;
input [6:0] commit_tgt;
input [DBW-1:0] commit_bus;
input which;
begin
if (commit_v && commit_tgt[6]) begin
    casex(commit_tgt[5:0])
    6'b00xxxx:  begin
                pregs[commit_tgt[3:0]] <= which ? cmt1nyb[commit_tgt[3:0]] : cmt0nyb[commit_tgt[3:0]];//commit_bus[3:0];
                    $display("pregs[%d]<=%h", commit_tgt[3:0], commit_bus[3:0]);
//                  $stop;
                end
    6'b01xxxx:  begin
                cregs[commit_tgt[3:0]] <= commit_bus;
                    $display("cregs[%d]<=%h", commit_tgt[3:0], commit_bus);
                   end
`ifdef SEGMENTATION
    6'b100xxx:  begin
                sregs[commit_tgt[2:0]] <= commit_bus[DBW-1:12];
                    $display("sregs[%d]<=%h", commit_tgt[2:0], commit_bus);
                    end
        6'b101xxx:  sregs_lmt[commit_tgt[2:0]] <= commit_bus[DBW-1:12];
`endif
    6'b110000:
        begin
        pregs[0] <= commit_bus[3:0];
        pregs[1] <= commit_bus[7:4];
        pregs[2] <= commit_bus[11:8];
        pregs[3] <= commit_bus[15:12];
        pregs[4] <= commit_bus[19:16];
        pregs[5] <= commit_bus[23:20];
        pregs[6] <= commit_bus[27:24];
        pregs[7] <= commit_bus[31:28];
        if (DBW==64) begin
            pregs[8] <= commit_bus[35:32];
            pregs[9] <= commit_bus[39:36];
            pregs[10] <= commit_bus[43:40];
            pregs[11] <= commit_bus[47:44];
            pregs[12] <= commit_bus[51:48];
            pregs[13] <= commit_bus[55:52];
            pregs[14] <= commit_bus[59:56];
            pregs[15] <= commit_bus[63:60];
        end
        end
    `LCTR:  begin    lc <= commit_bus; $display("LC <= %h", commit_bus); end
        `ASID:      asid <= commit_bus;
    `SR:    begin
            GM <= commit_bus[7:0];
            GMB <= commit_bus[23:16];
            imb <= commit_bus[31];
            im <= commit_bus[15];
            fxe <= commit_bus[12];
            end
    6'd60:  spr_bir <= commit_bus[11:0];
    6'd61:
            case(spr_bir[5:0])
            6'd0:   dbg_adr0 <= commit_bus;
            6'd1:   dbg_adr1 <= commit_bus;
            6'd2:   dbg_adr2 <= commit_bus;
            6'd3:   dbg_adr3 <= commit_bus;
            6'd4:   dbg_ctrl <= commit_bus;
            6'd5:   dbg_stat <= commit_bus;
`ifdef PCHIST
            6'd18:  pc_ndx <= commit_bus[5:0];
`endif
            default:    ;
            endcase
    6'b111111:
            begin
                ld_clk_throttle <= `TRUE;
                clk_throttle_new <= commit_bus[15:0];
            end
    default:    ;
    endcase
end
end
endtask
 
// For string memory operations.
// Indexing amount, should synth to a ROM.
//
function [63:0] fnIndexAmt;
input [5:0] fn;
begin
    case(fn[2:0])
    3'd0:   fnIndexAmt = 64'd1;
    3'd1:   fnIndexAmt = 64'd2;
    3'd2:   fnIndexAmt = 64'd4;
    3'd3:   fnIndexAmt = 64'd8;
    3'd4:   fnIndexAmt = 64'd1;
    3'd5:   fnIndexAmt = 64'd2;
    3'd6:   fnIndexAmt = 64'd4;
    3'd7:   fnIndexAmt = 64'd8;
    endcase
end
endfunction
 
 
// For string memory operations.
//
task inc_index;
input [5:0] fn;
begin
    index <= index + fnIndexAmt(fn);
    lc <= lc - 64'd1;
end
endtask
 
function [DBW-1:0] fnSpr;
input [5:0] regno;
input [63:0] epc;
begin
    // Read from the special registers unless overridden by the
    // value on the commit bus.
    casex(regno)
    6'b00xxxx:  fnSpr = {DBW/4{pregs[regno[3:0]]}};
    6'b01xxxx:  fnSpr = cregs[regno[3:0]];
`ifdef SEGMENTATION
    6'b100xxx:  fnSpr = {sregs[regno[2:0]],12'h000};
    6'b101xxx:  fnSpr = {sregs_lmt[regno[2:0]],12'h000};
`endif
    6'b110000:  if (DBW==64)
                fnSpr = {pregs[15],pregs[14],pregs[13],pregs[12],
                         pregs[11],pregs[10],pregs[9],pregs[8],
                         pregs[7],pregs[6],pregs[5],pregs[4],
                         pregs[3],pregs[2],pregs[1],pregs[0]};
                else
                fnSpr = {pregs[7],pregs[6],pregs[5],pregs[4],
                         pregs[3],pregs[2],pregs[1],pregs[0]};
    `TICK:      fnSpr = tick;
    `LCTR:      fnSpr = lc;
    `ASID:      fnSpr = asid;
    `SR:    begin
            fnSpr[7:0] = GM;
            fnSpr[23:16] = GMB;
            fnSpr[31] = imb;
            fnSpr[15] = im;
            fnSpr[12] = fxe;
            end
    6'd60:  fnSpr = spr_bir;
    6'd61:
            casex(spr_bir[5:0])
            6'd0:   fnSpr = dbg_adr0;
            6'd1:   fnSpr = dbg_adr1;
            6'd2:   fnSpr = dbg_adr2;
            6'd3:   fnSpr = dbg_adr3;
            6'd4:   fnSpr = dbg_ctrl;
            6'd5:   fnSpr = dbg_stat;
`ifdef PCHIST
            6'd16:  fnSpr = pc_histo[31:0];
            6'd17:  fnSpr = pc_histo[63:31];
`endif
            default:    fnSpr = 64'd0;
            endcase
    default:    fnSpr = 64'd0;
    endcase
// Not sure why bother read the commit bus here ? Why not the alu bus as well ?
// Need bypassing for write-through register file, reg read at same time as write
// Shaves a clock cycle off register updates. rf_v is being set valid on the
// clock cycle of the commit.   
    // If an spr is committing...
    if (commit0_v && commit0_tgt=={1'b1,regno}) begin
        if (regno[5:4]==2'b00) begin
            if (DBW==32)
                fnSpr = {8{cmt0nyb[regno[2:0]]}};
            else
                fnSpr = {16{cmt0nyb[regno[3:0]]}};
        end
        else
            fnSpr = commit0_bus;
    end
    if (commit1_v && commit1_tgt=={1'b1,regno}) begin
        if (regno[5:4]==2'b00) begin
            if (DBW==32)
                fnSpr = {8{cmt1nyb[regno[2:0]]}};
            else
                fnSpr = {16{cmt1nyb[regno[3:0]]}};
        end
        else
            fnSpr = commit1_bus;
    end
 
    // Special cases where the register would not be read from the commit bus
    case(regno)
    `TICK:      fnSpr = tick;
    6'b010000:  fnSpr = 64'd0;  // code address zero
    6'b011111:  fnSpr = epc;    // current program counter from fetchbufx_pc
    default:    ;
    endcase
end
endfunction
 
// "oddball" instruction commit cases.
//
task oddball_commit;
input commit_v;
input [2:0] head;
begin
    if (commit_v)
        case(iqentry_op[head])
        `CLI:   begin imcd <= IMCD; imb <= 1'b0; end
        `SEI:   begin im <= 1'b1; imb <= 1'b1; end
        // When the RTI instruction commits clear the hardware interrupt status to enable interrupts.
        `RTI:   begin
                StatusHWI <= `FALSE;
                if (imb)
                    im <= 1'b1;
                else
                    imcd <= IMCD;
                end
        `RTD:
                begin
                    StatusDBG <= `FALSE;
                    if (StatusEXL!=8'h00)
                        StatusEXL <= StatusEXL - 8'd1;
                end
        `RTE:
                begin
                    if (StatusEXL!=8'h00)
                        StatusEXL <= StatusEXL - 8'd1;
                end
        `CACHE:
               begin
                   case(iqentry_fn[head])
                   6'd0:   ic_invalidate <= `TRUE;
                   6'd1:   begin
                           ic_invalidate_line <= `TRUE;
                           ic_lineno <= iqentry_a1[head]  + {sregs[3'd7],12'h000};
                           end
                   6'd32:  dc_invalidate <= `TRUE;
                   6'd33:  begin
                           dc_invalidate_line <= `TRUE;
                           dc_lineno <= iqentry_a1[head] + {sregs[iqentry_fn[head][5:3]],12'h000};
                           end
                   default: ;   // do nothing
                   endcase
               end
        default:        ;
        endcase
end
endtask
 
// The exception_set var is used to reduce the number of logic levels. Rather
// than having an if/elseif tree for all the exceptional conditions that are
// trapped. The exception_set var tracks these excaptions and reduces the
// tree to a single if.
task enque0a;
input [2:0] tail;
input [2:0] inc;
input unlink;
begin
    if (fetchbuf0_pc==32'h0)
        $stop;
    if (fetchbuf0_pc==32'hF44)
        $stop;
    if (fetchbuf0_pc==32'hFFFC275A)
        $stop;
`ifdef SEGMENTATION
`ifdef SEGLIMITS
    // If segment limit exceeded and not in the non-segmented area.
    if (fetchbuf0_pc >= {sregs_lmt[3'd7],12'h000} && fetchbuf0_pc[ABW-1:ABW-4]!=4'hF)
        set_exception(tail,8'd244);
`endif
`endif
    // If targeting a kernel mode register and not in kernel mode.
    // But okay if it is an SYS or INT instruction.
    if (fnIsKMOnlyReg(Rt0) && !km && !(opcode0==`SYS || opcode0==`INT))
        set_exception(tail,8'd245);
    // If attempting to use an undefined instruction
`ifdef TRAP_ILLEGALOPS
    if (fnIsIllegal(opcode0,opcode0==`MLO ? rfoc0[5:0] : fnFunc(fetchbuf0_instr)))
        set_exception(tail,8'd250);
`endif
`ifdef DEBUG_LOGIC
    if (dbg_ctrl[0] && dbg_ctrl[17:16]==2'b00 && fetchbuf0_pc==dbg_adr0)
        dbg_imatchA0 = `TRUE;
    if (dbg_ctrl[1] && dbg_ctrl[21:20]==2'b00 && fetchbuf0_pc==dbg_adr1)
        dbg_imatchA1 = `TRUE;
    if (dbg_ctrl[2] && dbg_ctrl[25:24]==2'b00 && fetchbuf0_pc==dbg_adr2)
        dbg_imatchA2 = `TRUE;
    if (dbg_ctrl[3] && dbg_ctrl[29:28]==2'b00 && fetchbuf0_pc==dbg_adr3)
        dbg_imatchA3 = `TRUE;
    if (dbg_imatchA0|dbg_imatchA1|dbg_imatchA2|dbg_imatchA3)
        dbg_imatchA = `TRUE;
    if (dbg_imatchA)
        set_exception(tail,8'd243); // Debug exception
`endif
    if (!exception_set) begin
        interrupt_pc =
            // If the previous instruction was an interrupt, then inherit the address 
            (iqentry_op[(tail-3'd1)&7]==`INT && iqentry_v[(tail-3'd1)&7]==`VAL && iqentry_tgt[(tail-3'd1)&7][3:0]==4'hE) ?
            (string_pc != 0 ? string_pc : iqentry_pc[(tail-3'd1)&7]) :
            // Otherwise inherit the address of any preceding immediate prefix.
            (iqentry_op[(tail-3'd1)&7]==`IMM && iqentry_v[(tail-3'd1)&7]==`VAL) ?
                (string_pc != 0 ? string_pc : iqentry_pc[(tail-3'd1)&7]) :
            // Otherwise use the address of the interrupted instruction
            (string_pc != 0 ? string_pc : fetchbuf0_pc);
    iqentry_v    [tail]    <=   `VAL;
    iqentry_done [tail]    <=   `INV;
    iqentry_cmt  [tail]    <=   `TRUE;
    iqentry_out  [tail]    <=   `INV;
    iqentry_res  [tail]    <=   `ZERO;
    iqentry_insnsz[tail]   <=  fnInsnLength(fetchbuf0_instr);
    iqentry_op   [tail]    <=   opcode0;
    iqentry_fn   [tail]    <=   opcode0==`MLO ? rfoc0[5:0] : fnFunc(fetchbuf0_instr);
    iqentry_cond [tail]    <=   cond0;
    iqentry_bt   [tail]    <=   fnIsFlowCtrl(opcode0) && predict_taken0;
    iqentry_br   [tail]    <=   opcode0[7:4]==`BR;
    iqentry_agen [tail]    <=   `INV;
    iqentry_pc   [tail]    <=   (opcode0==`INT && Rt0[3:0]==4'hE) ? interrupt_pc : fetchbuf0_pc;
    iqentry_mem  [tail]    <=   fetchbuf0_mem;
    iqentry_ndx  [tail]    <=   fnIsIndexed(opcode0);
    iqentry_cas  [tail]    <=   opcode0==`CAS;
    iqentry_pushpop[tail]  <=   opcode0==`PUSH || opcode0==`POP;
    iqentry_pea  [tail]    <=   opcode0==`PEA;
    iqentry_cmpmv[tail]    <=   opcode0==`STCMP || opcode0==`STMV;
    iqentry_lla  [tail]    <=   opcode0==`LLA || opcode0==`LLAX;
    iqentry_tlb  [tail]    <=   opcode0==`TLB;
    iqentry_jmp  [tail]    <=   fetchbuf0_jmp;
    iqentry_jmpi [tail]    <=   opcode0==`JMPI || opcode0==`JMPIX;
    iqentry_sync [tail]    <=   opcode0==`SYNC;
    iqentry_memsb[tail]    <=   opcode0==`MEMSB;
    iqentry_memdb[tail]    <=   opcode0==`MEMDB;
    iqentry_fp   [tail]    <=   fetchbuf0_fp;
    iqentry_rfw  [tail]    <=   fetchbuf0_rfw;
    iqentry_tgt  [tail]    <=   Rt0;
    iqentry_preg [tail]    <=   Pn0;
    // Need the bypassing on the preg file for write-through register effect.
    iqentry_pred [tail]    <=   fnSpr({2'h0,Pn0},fetchbuf0_pc);//pregs[Pn0];
    // Look at the previous queue slot to see if an immediate prefix is enqueued
    iqentry_a0[tail]   <=       (opcode0==`INT || opcode0==`SYS) ? fnImm(fetchbuf0_instr) :
                                fnIsBranch(opcode0) ? {{DBW-12{fetchbuf0_instr[11]}},fetchbuf0_instr[11:8],fetchbuf0_instr[23:16]} :
                                (iqentry_op[(tail-3'd1)&7]==`IMM && iqentry_v[tail-3'd1]) ? {iqentry_a0[(tail-3'd1)&7][DBW-1:8],fnImm8(fetchbuf0_instr)}:
                                opcode0==`IMM ? fnImmImm(fetchbuf0_instr) :
                                fnImm(fetchbuf0_instr);
    // These register recordings for simulation debug. They should be stripped
    // out of synthesis because they don't drive any signals.
`ifdef SIMULATION
    iqentry_r1   [tail]    <=   Ra0;
    iqentry_r2   [tail]    <=   Rb0;
    iqentry_r3   [tail]    <=   Rc0;
    iqentry_rt   [tail]    <=   Rt0;
`endif
    iqentry_a1   [tail]    <=   fnOpa(opcode0,Ra0,fetchbuf0_instr,rfoa0,fetchbuf0_pc);
    iqentry_a2   [tail]    <=   fnOpb(opcode0,Rb0,fetchbuf0_instr,rfob0,fetchbuf0_pc);
    iqentry_a3   [tail]    <=   rfoc0;
    iqentry_T    [tail]    <=   fnOpt(Rt0,rfot0,fetchbuf0_pc);
    // The source is set even though the arg might be automatically valid (less logic).
    // This is harmless to do. Note there is no source for the 'I' argument.
    iqentry_p_s  [tail]    <=   rf_source[{1'b1,2'h0,Pn0}];
    iqentry_a1_s [tail]    <=   //unlink ? {1'b0, (tail-1)&7} :
                                 rf_source[Ra0];
    iqentry_a2_s [tail]    <=   rf_source[Rb0];
    iqentry_a3_s [tail]    <=   rf_source[Rc0];
    iqentry_T_s  [tail]    <=   rf_source[Rt0];
    // Always do this because it's the first queue slot.
    validate_args10(tail);
    end
    tail0 <= tail0 + inc;
    tail1 <= tail1 + inc;
    tail2 <= tail2 + inc;
    queued1 = `TRUE;
    rrmapno <= rrmapno + 3'd1;
end
endtask
 
task enquePushpopAdd;
input [2:0] tail;
input pushpop;
input link;
input unlink;
input which;
begin
    $display("Pushpop add");
    iqentry_v    [tail]    <=   `VAL;
    iqentry_done [tail]    <=   `INV;
    iqentry_cmt  [tail]    <=   `TRUE;
    iqentry_out  [tail]    <=   `INV;
    iqentry_res  [tail]    <=   64'd0;
    iqentry_insnsz[tail]   <=   4'd0;
    iqentry_op   [tail]    <=   `ADDUI;
    iqentry_fn   [tail]    <=   6'b0;
    iqentry_cond [tail]    <=   which ? cond1 :cond0;
    iqentry_bt   [tail]    <=   1'b0;
    iqentry_agen [tail]    <=   `INV;
    iqentry_pc   [tail]    <=   which ? fetchbuf1_pc : fetchbuf0_pc;
    iqentry_mem  [tail]    <=   1'b0;
    iqentry_ndx  [tail]    <=   1'b0;
    iqentry_cas  [tail]    <=   1'b0;
    iqentry_pushpop[tail]  <=   1'b0;
    iqentry_pea  [tail]    <=   1'b0;
    iqentry_cmpmv[tail]    <=   1'b0;
    iqentry_lla  [tail]    <=   1'b0;
    iqentry_tlb  [tail]    <=   1'b0;
    iqentry_jmp  [tail]    <=   1'b0;
    iqentry_jmpi [tail]    <=   1'b0;
    iqentry_sync [tail]    <=   1'b0;
    iqentry_memsb[tail]    <=   1'b0;
    iqentry_memdb[tail]    <=   1'b0;
    iqentry_fp   [tail]    <=   1'b0;
    iqentry_rfw  [tail]    <=   1'b1;
    iqentry_tgt  [tail]    <=   7'd27;
    iqentry_pred [tail]    <=   pregs[which ? Pn1 : Pn0];
    // Look at the previous queue slot to see if an immediate prefix is enqueued
    iqentry_a0   [tail]    <=   link ? (which ? {{46{fetchbuf1_instr[39]}},fetchbuf1_instr[21:16],fetchbuf1_instr[39:28],3'b000} :
                                                {{46{fetchbuf0_instr[39]}},fetchbuf0_instr[21:16],fetchbuf0_instr[39:28],3'b000}) :
                                (pushpop|unlink) ? 64'd8 : -64'd8;
    iqentry_a1   [tail]    <=   which ? rfoa1 : rfoa0;
    iqentry_a2   [tail]    <=   64'd0;
    iqentry_a3   [tail]    <=   64'd0;
    iqentry_T    [tail]    <=   //unlink ? (which ? rfot1 : rfot0) :
                                 (which ? rfoa1 : rfoa0);
    // The source is set even though the arg might be automatically valid (less logic).
    // This is harmless to do. Note there is no source for the 'I' argument.
    iqentry_p_s  [tail]    <=   rf_source[{1'b1,2'h0,which ? Pn1 : Pn0}];
    iqentry_a1_s [tail]    <=   rf_source[Ra0];
    iqentry_a2_s [tail]    <=   rf_source[Rb0];
    iqentry_a3_s [tail]    <=   rf_source[Rc0];
    iqentry_T_s  [tail]    <=   rf_source[Ra0];
    // Always do this because it's the first queue slot.
    iqentry_p_v  [tail]    <=   rf_v [{1'b1,2'h0,which ? Pn1:Pn0}] || ((which ? cond1 : cond0) < 4'h2);
    iqentry_a1_v [tail]    <=   rf_v[ which ? Ra1 :  Ra0 ];
    iqentry_a2_v [tail]    <=   1'b1;
    iqentry_a3_v [tail]    <=   1'b1;
    iqentry_T_v  [tail]    <=   //unlink ? rf_v[which ? Rt1 : Rt0] :
                                rf_v[ which ? Ra1 :  Ra0 ];
    rf_v[ 7'd27 ] = `INV;
    rf_source[ 7'd27 ] <= { 1'b0, tail };    // top bit indicates ALU/MEM bus
end
endtask
 
// enque 0 on tail0 or tail1
task enque0;
input [2:0] tail;
input [2:0] inc;
input test_stomp;
input validate_args;
begin
    if (opcode0==`NOP)
        queued1 = `TRUE;    // to update fetch buffers
`ifdef DEBUG_LOGIC
    else
    if (dbg_ctrl[7] && !StatusDBG) begin
        if (iqentry_v[tail]==`INV && iqentry_v[(tail+1)&7]==`INV) begin
            enque0a(tail,3'd2,1'b0);
            set_exception((tail+1)&7,8'd243);
            allowq = `FALSE;
        end
    end
`endif
`ifdef STACKOPS
    // A pop instruction takes 2 queue entries.
    else if (fnIsPop(fetchbuf0_instr)|fnIsPush(fetchbuf0_instr)|opcode0==`LINK) begin
        $display("0 found push/pop");
        if (iqentry_v[tail]==`INV && iqentry_v[(tail+1)&7]==`INV) begin
            $display("enqueing2");
            enque0a(tail,3'd2,1'b0);
            enquePushpopAdd((tail+1)&7,fnIsPop(fetchbuf0_instr),opcode0==`LINK,0,0);
            allowq = `FALSE;
        end
    end
`ifdef UNLINKOP
    else if (opcode0==`UNLINK) begin
        if (iqentry_v[tail]==`INV && iqentry_v[(tail+1)&7]==`INV) begin
            enquePushpopAdd(tail,1'b0,1'b0,1'b1,0);
            enque0a((tail+1)&7,3'd2,1'b1);
            allowq = `FALSE;
        end
    end
`endif
`endif
    else if (iqentry_v[tail] == `INV) begin
        if ((({fnIsBranch(opcode0), predict_taken0} == {`TRUE, `TRUE})||(opcode0==`LOOP)) && test_stomp)
            qstomp = `TRUE;
        enque0a(tail,inc,0);
    end
end
endtask
 
task enque1a;
input [2:0] tail;
input [2:0] inc;
input validate_args;
input unlink;
begin
    if (fetchbuf1_pc==32'h0)
        $stop;
    if (fetchbuf1_pc==32'hF44)
        $stop;
    if (fetchbuf1_pc==32'hFFFC275A)
        $stop;
`ifdef SEGMENTATION
`ifdef SEGLIMITS
    if (fetchbuf1_pc >= {sregs_lmt[3'd7],12'h000} && fetchbuf1_pc[ABW-1:ABW-4]!=4'hF)
        set_exception(tail,8'd244);
`endif
`endif
    if (fnIsKMOnlyReg(Rt1) && !km && !(opcode1==`SYS || opcode1==`INT))
        set_exception(tail,8'd245);
`ifdef TRAP_ILLEGALOPS
    if (fnIsIllegal(opcode1,opcode1==`MLO ? rfoc1[5:0] : fnFunc(fetchbuf1_instr)))
        set_exception(tail,8'd250);
`endif
`ifdef DEBUG_LOGIC
    if (dbg_ctrl[0] && dbg_ctrl[17:16]==2'b00 && fetchbuf1_pc==dbg_adr0)
        dbg_imatchB0 = `TRUE;
    if (dbg_ctrl[1] && dbg_ctrl[21:20]==2'b00 && fetchbuf1_pc==dbg_adr1)
        dbg_imatchB1 = `TRUE;
    if (dbg_ctrl[2] && dbg_ctrl[25:24]==2'b00 && fetchbuf1_pc==dbg_adr2)
        dbg_imatchB2 = `TRUE;
    if (dbg_ctrl[3] && dbg_ctrl[29:28]==2'b00 && fetchbuf1_pc==dbg_adr3)
        dbg_imatchB3 = `TRUE;
    if (dbg_imatchB0|dbg_imatchB1|dbg_imatchB2|dbg_imatchB3)
        dbg_imatchB = `TRUE;
    if (dbg_imatchB)
        set_exception(tail,8'd243);     // debug excpetion
`endif
    if (!exception_set) begin
    // If an instruction wasn't enqueued or it wasn't an interrupt instruction then
    // the interrupt pc will need to be set. Othersise this enqueue will inherit
    // from the previous one.
    if (!queued1 || !(opcode0==`INT && Rt0[3:0]==4'hE))
        interrupt_pc = (iqentry_op[(tail-3'd1)&7]==`INT && iqentry_v[(tail-3'd1)&7]==`VAL && iqentry_tgt[(tail-3'd1)&7][3:0]==4'hE) ?
            (string_pc != 0 ? string_pc : iqentry_pc[(tail-3'd1)&7]) :
            (iqentry_op[(tail-3'd1)&7]==`IMM && iqentry_v[(tail-3'd1)&7]==`VAL) ? (string_pc != 0 ? string_pc :
            iqentry_pc[(tail-3'd1)&7]) : (string_pc != 0 ? string_pc : fetchbuf1_pc);
    iqentry_v    [tail]    <=   `VAL;
    iqentry_done [tail]    <=   `INV;
    iqentry_cmt  [tail]    <=   `TRUE;
    iqentry_out  [tail]    <=   `INV;
    iqentry_res  [tail]    <=   `ZERO;
    iqentry_insnsz[tail]   <=  fnInsnLength(fetchbuf1_instr);
    iqentry_op   [tail]    <=   opcode1;
    iqentry_fn   [tail]    <=   opcode1==`MLO ? rfoc1[5:0] : fnFunc(fetchbuf1_instr);
    iqentry_cond [tail]    <=   cond1;
    iqentry_bt   [tail]    <=   fnIsFlowCtrl(opcode1) && predict_taken1;
    iqentry_br   [tail]    <=   opcode1[7:4]==`BR;
    iqentry_agen [tail]    <=   `INV;
    // If an interrupt is being enqueued and the previous instruction was an immediate prefix, then
    // inherit the address of the previous instruction, so that the prefix will be executed on return
    // from interrupt.
    // If a string operation was in progress then inherit the address of the string operation so that
    // it can be continued.
 
    iqentry_pc   [tail]    <= (opcode1==`INT && Rt1[3:0]==4'hE) ? interrupt_pc : fetchbuf1_pc;
    iqentry_mem  [tail]    <=   fetchbuf1_mem;
    iqentry_ndx  [tail]    <=   fnIsIndexed(opcode1);
    iqentry_cas  [tail]    <=   opcode1==`CAS;
    iqentry_pushpop[tail]  <=   opcode1==`PUSH || opcode1==`POP;
    iqentry_pea  [tail]    <=   opcode1==`PEA;
    iqentry_cmpmv[tail]    <=   opcode1==`STCMP || opcode1==`STMV;
    iqentry_lla  [tail]    <=   opcode1==`LLA || opcode1==`LLAX;
    iqentry_tlb  [tail]    <=   opcode1==`TLB;
    iqentry_jmp  [tail]    <=   fetchbuf1_jmp;
    iqentry_jmpi [tail]    <=   opcode1==`JMPI || opcode1==`JMPIX;
    iqentry_sync [tail]    <=   opcode1==`SYNC;
    iqentry_memsb[tail]    <=   opcode1==`MEMSB;
    iqentry_memdb[tail]    <=   opcode1==`MEMDB;
    iqentry_fp   [tail]    <=   fetchbuf1_fp;
    iqentry_rfw  [tail]    <=   fetchbuf1_rfw;
    iqentry_tgt  [tail]    <=   Rt1;
    iqentry_preg [tail]    <=   Pn1;
    iqentry_pred [tail]    <=   fnSpr({2'h0,Pn1},fetchbuf1_pc);//pregs[Pn1];
    // Look at the previous queue slot to see if an immediate prefix is enqueued
    // But don't allow it for a branch
    iqentry_a0[tail]   <=       (opcode1==`INT || opcode1==`SYS) ? fnImm(fetchbuf1_instr) :
                                fnIsBranch(opcode1) ? {{DBW-12{fetchbuf1_instr[11]}},fetchbuf1_instr[11:8],fetchbuf1_instr[23:16]} :
                                (queued1 && opcode0==`IMM) ? {fnImmImm(fetchbuf0_instr)|fnImm8(fetchbuf1_instr)} :
                                (!queued1 && iqentry_op[(tail-3'd1)&7]==`IMM) && iqentry_v[(tail-3'd1)&7] ? {iqentry_a0[(tail-3'd1)&7][DBW-1:8],fnImm8(fetchbuf1_instr)} :
                                opcode1==`IMM ? fnImmImm(fetchbuf1_instr) :
                                fnImm(fetchbuf1_instr);
    iqentry_a1   [tail]    <=   fnOpa(opcode1,Ra1,fetchbuf1_instr,rfoa1,fetchbuf1_pc);
    iqentry_a2   [tail]    <=   fnOpb(opcode1,Rb1,fetchbuf1_instr,rfob1,fetchbuf1_pc);
    iqentry_a3   [tail]    <=   rfoc1;
    iqentry_T    [tail]    <=   fnOpt(Rt1,rfot1,fetchbuf1_pc);
`ifdef SIMULATION
    iqentry_r1   [tail]    <=   Ra1;
    iqentry_r2   [tail]    <=   Rb1;
    iqentry_r3   [tail]    <=   Rc1;
    iqentry_rt   [tail]    <=   Rt1;
`endif
    // The source is set even though the arg might be automatically valid (less logic). If 
    // queueing two entries the source settings may be overridden in the argument valudation.
    iqentry_p_s  [tail]    <=   rf_source[{1'b1,2'h0,Pn1}];
    iqentry_a1_s [tail]    <=   //unlink ? {1'b0, (tail-3'd1)&7} :
                                rf_source[Ra1];
    iqentry_a2_s [tail]    <=   rf_source[Rb1];
    iqentry_a3_s [tail]    <=   rf_source[Rc1];
    iqentry_T_s  [tail]    <=   rf_source[Rt1];
    if (validate_args)
        validate_args11(tail);
    end
    tail0 <= tail0 + inc;
    tail1 <= tail1 + inc;
    tail2 <= tail2 + inc;
end
endtask
 
// enque 1 on tail0 or tail1
task enque1;
input [2:0] tail;
input [2:0] inc;
input test_stomp;
input validate_args;
begin
    if (opcode1==`NOP) begin
        if (queued1==`TRUE) queued2 = `TRUE;
        queued1 = `TRUE;
    end
`ifdef DEBUG_LOGIC
    else
    if (dbg_ctrl[7] && !StatusDBG) begin
        if (iqentry_v[tail]==`INV && iqentry_v[(tail+1)&7]==`INV) begin
            enque1a(tail,3'd2,1,0);
            set_exception((tail+1)&7,8'd243);
            allowq = `FALSE;
        end
    end
`endif
`ifdef STACKOPS
    else if (fnIsPop(fetchbuf1_instr)|fnIsPush(fetchbuf1_instr)|opcode1==`LINK) begin
        $display("1 found push/pop");
        $display("iqv[%d]:%d", tail,iqentry_v[tail]);
        $display("iqv[%d+1]:%d", tail, iqentry_v[tail+1]);
        $display("valargs:%d", validate_args);
        $display("qd1:%d", queued1);
        if (iqentry_v[tail]==`INV && iqentry_v[(tail+1)&7]==`INV && validate_args && !queued1) begin
            $display("1 enq 2 ");
            enque1a(tail,3'd2,1,0);
            enquePushpopAdd((tail+1)&7,fnIsPop(fetchbuf1_instr),opcode1==`LINK,0,1);
            allowq = `FALSE;
        end
    end
`ifdef UNLINKOP
    else if (opcode1==`UNLINK) begin
        if (iqentry_v[tail]==`INV && iqentry_v[(tail+1)&7]==`INV) begin
            enquePushpopAdd(tail,1'b0,1'b0,1'b1,1);
            enque1a((tail+1)&7,3'd2,1,1);
            allowq = `FALSE;
        end
    end
`endif
`endif
    else if (iqentry_v[tail] == `INV && !qstomp) begin
        if ((({fnIsBranch(opcode1), predict_taken1} == {`TRUE, `TRUE})||(opcode1==`LOOP)) && test_stomp)
            qstomp = `TRUE;
        enque1a(tail,inc,validate_args,0);
        if (queued1==`TRUE) queued2 = `TRUE;
        else queued1 = `TRUE;
    end
end
endtask
 
task validate_args10;
input [2:0] tail;
begin
    iqentry_p_v  [tail]    <=   rf_v [{1'b1,2'h0,Pn0}] || cond0 < 4'h2;
    iqentry_a1_v [tail]    <=   fnSource1_v( opcode0 ) | rf_v[ Ra0 ];
    iqentry_a2_v [tail]    <=   fnSource2_v( opcode0, fnFunc(fetchbuf0_instr)) | rf_v[Rb0];
    iqentry_a3_v [tail]    <=   fnSource3_v( opcode0, fnFunc(fetchbuf0_instr)) | rf_v[ Rc0 ];
    iqentry_T_v  [tail]    <=   fnSourceT_v( opcode0, fnFunc(fetchbuf0_instr)) | rf_v[ Rt0 ];
    if (fetchbuf0_rfw|fetchbuf0_pfw) begin
        $display("regv[%d] = %d", Rt0,rf_v[ Rt0 ]);
        rf_v[ Rt0 ] = fnRegIsAutoValid(Rt0);
        $display("reg[%d] <= INV",Rt0);
        rf_source[ Rt0 ] <= { fetchbuf0_mem, tail };    // top bit indicates ALU/MEM bus
        $display("10:rf_src[%d] <= %d, insn=%h", Rt0, tail,fetchbuf0_instr);
        invalidate_pregs(tail, Rt0, fetchbuf0_mem);
    end
end
endtask
 
task validate_args11;
input [2:0] tail;
begin
    // The predicate is automatically valid for condiitions 0 and 1 (always false or always true).
    iqentry_p_v  [tail]    <=   rf_v [{1'b1,2'h0,Pn1}] || cond1 < 4'h2;
    iqentry_a1_v [tail]    <=   fnSource1_v( opcode1 ) | rf_v[ Ra1 ];
    iqentry_a2_v [tail]    <=   fnSource2_v( opcode1, fnFunc(fetchbuf1_instr)) | rf_v[ Rb1 ];
    iqentry_a3_v [tail]    <=   fnSource3_v( opcode1, fnFunc(fetchbuf1_instr)) | rf_v[ Rc1 ];
    iqentry_T_v  [tail]    <=   fnSourceT_v( opcode1, fnFunc(fetchbuf1_instr)) | rf_v[ Rt1 ];
    if (fetchbuf1_rfw|fetchbuf1_pfw) begin
        $display("1:regv[%d] = %d", Rt1,rf_v[ Rt1 ]);
        rf_v[ Rt1 ] = fnRegIsAutoValid(Rt1);
        $display("reg[%d] <= INV",Rt1);
        rf_source[ Rt1 ] <= { fetchbuf1_mem, tail };    // top bit indicates ALU/MEM bus
        invalidate_pregs(tail, Rt1, fetchbuf1_mem);
        $display("11:rf_src[%d] <= %d, insn=%h", Rt1, tail,fetchbuf0_instr);
    end
end
endtask
 
// If two entries were queued then validate the arguments for the second entry.
//
task validate_args;
begin
    if (queued2) begin
    // SOURCE 1 ... this is relatively straightforward, because all instructions
       // that have a source (i.e. every instruction but LUI) read from RB
       //
       // if the argument is an immediate or not needed, we're done
       if (fnSource1_v( opcode1 ) == `VAL) begin
           $display("fnSource1_v=1 iq[%d]", tail1);
           iqentry_a1_v [tail1] <= `VAL;
           iqentry_a1_s [tail1] <= 4'hF;
//                    iqentry_a1_s [tail1] <= 4'd0;
       end
       // if previous instruction writes nothing to RF, then get info from rf_v and rf_source
       else if (!fetchbuf0_rfw) begin
           iqentry_a1_v [tail1]    <=   rf_v [Ra1];
           iqentry_a1_s [tail1]    <=   rf_source [Ra1];
       end
       // otherwise, previous instruction does write to RF ... see if overlap
       else if (Rt0 != 7'd0 && Ra1 == Rt0) begin
           // if the previous instruction is a LW, then grab result from memq, not the iq
           $display("invalidating iqentry_a1_v[%d]", tail1);
           iqentry_a1_v [tail1]    <=   `INV;
           iqentry_a1_s [tail1]    <=   {fetchbuf0_mem, tail0};
       end
       // if no overlap, get info from rf_v and rf_source
       else begin
           iqentry_a1_v [tail1]    <=   rf_v [Ra1];
           iqentry_a1_s [tail1]    <=   rf_source [Ra1];
           $display("2:iqentry_a1_s[%d] <= %d", tail1, rf_source [Ra1]);
       end
 
       if (!fetchbuf0_pfw) begin
           iqentry_p_v  [tail1]    <=   rf_v [{1'b1,2'h0,Pn1}] || cond1 < 4'h2;
           iqentry_p_s  [tail1]    <=   rf_source [{1'b1,2'h0,Pn1}];
       end
       else if ((Rt0 != 7'd0 && (Pn1==Rt0[3:0] || Rt0==7'h70)) && ((Rt0 & 7'h70)==7'h40)||Rt0==7'h70) begin
           iqentry_p_v [tail1] <= cond1 < 4'h2;
           iqentry_p_s [tail1] <= {fetchbuf0_mem, tail0};
       end
       else begin
           iqentry_p_v [tail1] <= rf_v[{1'b1,2'h0,Pn1}] || cond1 < 4'h2;
           iqentry_p_s [tail1] <= rf_source[{1'b1,2'h0,Pn1}];
       end
 
       //
       // SOURCE 2 ... this is more contorted than the logic for SOURCE 1 because
       // some instructions (NAND and ADD) read from RC and others (SW, BEQ) read from RA
       //
       // if the argument is an immediate or not needed, we're done
       if (fnSource2_v( opcode1,fnFunc(fetchbuf1_instr) ) == `VAL) begin
           iqentry_a2_v [tail1] <= `VAL;
           iqentry_a2_s [tail1] <= 4'hF;
       end
       // if previous instruction writes nothing to RF, then get info from rf_v and rf_source
       else if (!fetchbuf0_rfw) begin
           iqentry_a2_v [tail1] <= rf_v[ Rb1 ];
           iqentry_a2_s [tail1] <= rf_source[Rb1];
       end
       // otherwise, previous instruction does write to RF ... see if overlap
       else if (Rt0 != 7'd0 && Rb1 == Rt0) begin
           // if the previous instruction is a LW, then grab result from memq, not the iq
           iqentry_a2_v [tail1]    <=   `INV;
           iqentry_a2_s [tail1]    <=   {fetchbuf0_mem,tail0};
       end
       // if no overlap, get info from rf_v and rf_source
       else begin
           iqentry_a2_v [tail1] <= rf_v[ Rb1 ];
           iqentry_a2_s [tail1] <= rf_source[Rb1];
       end
 
       //
       // SOURCE 3 ... this is relatively straightforward, because all instructions
       // that have a source (i.e. every instruction but LUI) read from RC
       //
       // if the argument is an immediate or not needed, we're done
       if (fnSource3_v( opcode1,fnFunc(fetchbuf1_instr) ) == `VAL) begin
           iqentry_a3_v [tail1] <= `VAL;
           iqentry_a3_v [tail1] <= 4'hF;
//                    iqentry_a1_s [tail1] <= 4'd0;
       end
       // if previous instruction writes nothing to RF, then get info from rf_v and rf_source
       else if (!fetchbuf0_rfw) begin
           iqentry_a3_v [tail1]    <=   rf_v [Rc1];
           iqentry_a3_s [tail1]    <=   rf_source [Rc1];
       end
       // otherwise, previous instruction does write to RF ... see if overlap
       else if (Rt0 != 7'd0 && Rc1 == Rt0) begin
           // if the previous instruction is a LW, then grab result from memq, not the iq
           iqentry_a3_v [tail1]    <=   `INV;
           iqentry_a3_s [tail1]    <=   {fetchbuf0_mem,tail0};
       end
       // if no overlap, get info from rf_v and rf_source
       else begin
           iqentry_a3_v [tail1]    <=   rf_v [Rc1];
           iqentry_a3_s [tail1]    <=   rf_source [Rc1];
       end
 
 
       //
       // Target 3 ... this is relatively straightforward, because all instructions
       // that have a source (i.e. every instruction but LUI) read from RC
       //
       // if the argument is an immediate or not needed, we're done
       if (fnSourceT_v( opcode1,fnFunc(fetchbuf1_instr) ) == `VAL) begin
           iqentry_T_v [tail1] <= `VAL;
           iqentry_T_v [tail1] <= 4'hF;
       end
       // if previous instruction writes nothing to RF, then get info from rf_v and rf_source
       else if (!fetchbuf0_rfw) begin
           iqentry_T_v [tail1]    <=   rf_v [Rt1];
           iqentry_T_s [tail1]    <=   rf_source [Rt1];
       end
       // otherwise, previous instruction does write to RF ... see if overlap
       else if (Rt0 != 7'd0 && Rt1 == Rt0) begin
           // if the previous instruction is a LW, then grab result from memq, not the iq
           iqentry_T_v [tail1]    <=   `INV;
           iqentry_T_s [tail1]    <=   {fetchbuf0_mem,tail0};
       end
       // if no overlap, get info from rf_v and rf_source
       else begin
           iqentry_T_v [tail1]    <=   rf_v [Rt1];
           iqentry_T_s [tail1]    <=   rf_source [Rt1];
       end
    end
    if (queued1|queued2) begin
        if (fetchbuf0_rfw|fetchbuf0_pfw) begin
            $display("regv[%d] = %d", Rt0,rf_v[ Rt0 ]);
            rf_v[ Rt0 ] = fnRegIsAutoValid(Rt0);
            $display("reg[%d] <= INV",Rt0);
            rf_source[ Rt0 ] <= { fetchbuf0_mem, tail0 };    // top bit indicates ALU/MEM bus
            $display("12:rf_src[%d] <= %d, insn=%h", Rt0, tail0,fetchbuf0_instr);
            invalidate_pregs(tail0, Rt0, fetchbuf0_mem);
        end
    end
    if (queued2) begin
        if (fetchbuf1_rfw|fetchbuf1_pfw) begin
            $display("1:regv[%d] = %d", Rt1,rf_v[ Rt1 ]);
            rf_v[ Rt1 ] = fnRegIsAutoValid(Rt1);
            $display("reg[%d] <= INV",Rt1);
            rf_source[ Rt1 ] <= { fetchbuf1_mem, tail1 };    // top bit indicates ALU/MEM bus
            invalidate_pregs(tail1, Rt1, fetchbuf1_mem);
        end
    end
end
endtask
 
task fetchAB;
begin
    fetchbufA_instr <= insn0;
    fetchbufA_pc <= pc;
    fetchbufA_v <= ld_fetchbuf;
    fetchbufB_instr <= insn1;
    fetchbufB_pc <= pc + fnInsnLength(insn);
    fetchbufB_v <= ld_fetchbuf;
end
endtask
 
task fetchCD;
begin
    fetchbufC_instr <= insn0;
    fetchbufC_pc <= pc;
    fetchbufC_v <= ld_fetchbuf;
    fetchbufD_instr <= insn1;
    fetchbufD_pc <= pc + fnInsnLength(insn);
    fetchbufD_v <= ld_fetchbuf;
end
endtask
 
// Reset the tail pointers.
// Used by the enqueue logic
//
task reset_tail_pointers;
input first;
begin
    if ((iqentry_stomp[0] & ~iqentry_stomp[7]) | first) begin
        tail0 <= 0;
        tail1 <= 1;
    end
    else if (iqentry_stomp[1] & ~iqentry_stomp[0]) begin
        tail0 <= 1;
        tail1 <= 2;
    end
    else if (iqentry_stomp[2] & ~iqentry_stomp[1]) begin
        tail0 <= 2;
        tail1 <= 3;
    end
    else if (iqentry_stomp[3] & ~iqentry_stomp[2]) begin
        tail0 <= 3;
        tail1 <= 4;
    end
    else if (iqentry_stomp[4] & ~iqentry_stomp[3]) begin
        tail0 <= 4;
        tail1 <= 5;
    end
    else if (iqentry_stomp[5] & ~iqentry_stomp[4]) begin
        tail0 <= 5;
        tail1 <= 6;
    end
    else if (iqentry_stomp[6] & ~iqentry_stomp[5]) begin
        tail0 <= 6;
        tail1 <= 7;
    end
    else if (iqentry_stomp[7] & ~iqentry_stomp[6]) begin
        tail0 <= 7;
        tail1 <= 0;
    end
    // otherwise, it is the last instruction in the queue that has been mispredicted ... do nothing
end
endtask
 
// Increment the head pointers
// Also increments the instruction counter
// Used when instructions are committed.
// Also clear any outstanding state bits that foul things up.
//
task head_inc;
input [2:0] amt;
begin
    head0 <= head0 + amt;
    head1 <= head1 + amt;
    head2 <= head2 + amt;
    head3 <= head3 + amt;
    head4 <= head4 + amt;
    head5 <= head5 + amt;
    head6 <= head6 + amt;
    head7 <= head7 + amt;
    I <= I + amt;
    if (amt==3'd3) begin
    iqentry_agen[head0] <= `INV;
    iqentry_agen[head1] <= `INV;
    iqentry_agen[head2] <= `INV;
    end else if (amt==3'd2) begin
    iqentry_agen[head0] <= `INV;
    iqentry_agen[head1] <= `INV;
    end else if (amt==3'd1)
            iqentry_agen[head0] <= `INV;
end
endtask
 
 
// set_exception:
// Used to requeue the instruction as an exception if an exception occurs.
 
task set_exception;
input [2:0] id;     // instruction queue id
input [7:0] exc;    // exception number
begin
    iqentry_op [id[2:0] ] <= `INT;
    iqentry_cond [id[2:0]] <= 4'd1;        // always execute
    iqentry_mem[id[2:0]] <= `FALSE;
    iqentry_rfw[id[2:0]] <= `TRUE;            // writes to IPC
    iqentry_a0 [id[2:0]] <= exc;
    iqentry_p_v  [id[2:0]] <= `TRUE;
    iqentry_a1 [id[2:0]] <= cregs[4'hC];    // *** assumes BR12 is static
    iqentry_a1_v [id[2:0]] <= `TRUE;        // Flag arguments as valid
    iqentry_a2_v [id[2:0]] <= `TRUE;
    iqentry_a3_v [id[2:0]] <= `TRUE;
    iqentry_T_v  [id[2:0]] <= `TRUE;
    iqentry_out [id[2:0]] <= `FALSE;
    iqentry_agen [id[2:0]] <= `FALSE;
    iqentry_tgt[id[2:0]] <= {1'b1,2'h1,(exc==8'd243)?4'hB:4'hD};    // Target EPC
    exception_set = `TRUE;
end
endtask
 
// The core should really invalidate all the predicate registers when the
// sideways slice of all the pregs is manipulated. But then the problem is
// reading the result register into all the predicate registers at once.
// The source for each register would be a bit field of the result register
// and the core does not support this sort of thing.
// So. After manipulating the sideways slice of predicate registers the
// instruction should be followed with a SYNC instruction to ensure that
// the results are picked up.
// To be fixed one day.
task invalidate_pregs;
input [2:0] tail;
input [6:0] Rt;
input mem;
begin
if (Rt==7'h70) begin
    rf_v[7'h40] = `INV;
    rf_v[7'h41] = `INV;
    rf_v[7'h42] = `INV;
    rf_v[7'h43] = `INV;
    rf_v[7'h44] = `INV;
    rf_v[7'h45] = `INV;
    rf_v[7'h46] = `INV;
    rf_v[7'h47] = `INV;
    rf_v[7'h48] = `INV;
    rf_v[7'h49] = `INV;
    rf_v[7'h4A] = `INV;
    rf_v[7'h4B] = `INV;
    rf_v[7'h4C] = `INV;
    rf_v[7'h4D] = `INV;
    rf_v[7'h4E] = `INV;
    rf_v[7'h4F] = `INV;
    rf_source[7'h40] <= { mem, tail };
    rf_source[7'h41] <= { mem, tail };
    rf_source[7'h42] <= { mem, tail };
    rf_source[7'h43] <= { mem, tail };
    rf_source[7'h44] <= { mem, tail };
    rf_source[7'h45] <= { mem, tail };
    rf_source[7'h46] <= { mem, tail };
    rf_source[7'h47] <= { mem, tail };
    rf_source[7'h48] <= { mem, tail };
    rf_source[7'h49] <= { mem, tail };
    rf_source[7'h4A] <= { mem, tail };
    rf_source[7'h4B] <= { mem, tail };
    rf_source[7'h4C] <= { mem, tail };
    rf_source[7'h4D] <= { mem, tail };
    rf_source[7'h4E] <= { mem, tail };
    rf_source[7'h4F] <= { mem, tail };
end
end
endtask
 
endmodule
Line No.	Rev	Author	Line
1	3	robfinch	`//`
2			`// COPYRIGHT 2000 by Bruce L. Jacob`
3			`// (contact info: http://www.ece.umd.edu/~blj/)`
4			`//`
5			`// You are welcome to use, modify, copy, and/or redistribute this implementation, provided:`
6			`// 1. you share with the author (Bruce Jacob) any changes you make;`
7			`// 2. you properly credit the author (Bruce Jacob) if used within a larger work; and`
8			`// 3. you do not modify, delete, or in any way obscure the implementation's copyright`
9			`// notice or following comments (i.e. the first 3-4 dozen lines of this file).`
10			`//`
11			`// RiSC-16`
12			`//`
13			`// This is an out-of-order implementation of the RiSC-16, a teaching instruction-set used by`
14			`// the author at the University of Maryland, and which is a blatant (but sanctioned) rip-off`
15			`// of the Little Computer (LC-896) developed by Peter Chen at the University of Michigan.`
16			`// The primary differences include the following:`
17			`// 1. a move from 17-bit to 16-bit instructions; and`
18			`// 2. the replacement of the NOP and HALT opcodes by ADDI and LUI ... HALT and NOP are`
19			`// now simply special instances of other instructions: NOP is a do-nothing ADD, and`
20			`// HALT is a subset of JALR.`
21			`//`
22			`// RiSC stands for Ridiculously Simple Computer, which makes sense in the context in which`
23			`// the instruction-set is normally used -- to teach simple organization and architecture to`
24			`// undergraduates who do not yet know how computers work. This implementation was targetted`
25			`// towards more advanced undergraduates doing design & implementation and was intended to`
26			`// demonstrate some high-performance concepts on a small scale -- an 8-entry reorder buffer,`
27			`// eight opcodes, two ALUs, two-way issue, two-way commit, etc. However, the out-of-order`
28			`// core is much more complex than I anticipated, and I hope that its complexity does not`
29			`// obscure its underlying structure. We'll see how well it flies in class ...`
30			`//`
31			`// CAVEAT FREELOADER: This Verilog implementation was developed and debugged in a (somewhat`
32			`// frantic) 2-week period before the start of the Fall 2000 semester. Not surprisingly, it`
33			`// still contains many bugs and some horrible, horrible logic. The logic is also written so`
34			`// as to be debuggable and/or explain its function, rather than to be efficient -- e.g. in`
35			`// several places, signals are over-constrained so that they are easy to read in the debug`
36			`// output ... also, you will see statements like`
37			`//`
38			// if (xyz[`INSTRUCTION_OP] == `BEQ \|\| xyz[`INSTRUCTION_OP] == `SW)
39			`//`
40			`// instead of and/nand combinations of bits ... sorry; can't be helped. Use at your own risk.`
41			`//`
42			`// DOCUMENTATION: Documents describing the RiSC-16 in all its forms (sequential, pipelined,`
43			`// as well as out-of-order) can be found on the author's website at the following URL:`
44			`//`
45			`// http://www.ece.umd.edu/~blj/RiSC/`
46			`//`
47			`// If you do not find what you are looking for, please feel free to email me with suggestions`
48			`// for more/different/modified documents. Same goes for bug fixes.`
49			`//`
50			`//`
51			`// KNOWN PROBLEMS (i.e., bugs I haven't got around to fixing yet)`
52			`//`
53			`// - If the target of a backwards branch is a backwards branch, the fetchbuf steering logic`
54			`// will get confused. This can be fixed by having a separate did_branchback status register`
55			`// for each of the fetch buffers.`
56			`//`
57			`// ============================================================================`
58			`// __`
59	37	robfinch	`// \\__/ o\ (C) 2013-2016 Robert Finch, Stratford`
60	3	robfinch	`// \ __ / All rights reserved.`
61			`// \/_// robfinch<remove>@finitron.ca`
62			`// \|\|`
63			`//`
64			`// This source file is free software: you can redistribute it and/or modify`
65			`// it under the terms of the GNU Lesser General Public License as published`
66			`// by the Free Software Foundation, either version 3 of the License, or`
67			`// (at your option) any later version.`
68			`//`
69			`// This source file is distributed in the hope that it will be useful,`
70			`// but WITHOUT ANY WARRANTY; without even the implied warranty of`
71			`// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the`
72			`// GNU General Public License for more details.`
73			`//`
74			`// You should have received a copy of the GNU General Public License`
75			`// along with this program. If not, see <http://www.gnu.org/licenses/>.`
76			`//`
77			`//`
78			`// Thor Superscaler`
79			`//`
80			`// This work is starting with the RiSC-16 as noted in the copyright statement`
81			`// above. Hopefully it will be possible to run this processor in real hardware`
82			`// (FPGA) as opposed to just simulation. To the RiSC-16 are added:`
83			`//`
84			`// 64/32 bit datapath rather than 16 bit`
85			`// 64 general purpose registers`
86			`// 16 code address registers`
87			`// 16 predicate registers / predicated instruction execution`
88			`// 8 segment registers`
89			`// A branch history table, and a (2,2) correlating branch predictor added`
90			`// variable length instruction encodings (code density)`
91			`// support for interrupts`
92			`// The instruction set is changed completely with many new instructions.`
93			`// An instruction and data cache were added.`
94			`// A WISHBONE bus interface was added,`
95			`//`
96	9	robfinch	`// 53,950 (86,500 LC's)`
97	3	robfinch	`// with segmentation`
98			`// no bitfield, stack or FP ops`
99			`//`
100			`// ============================================================================`
101			`//`
102			`include "Thor_defines.v"
103
104			`module Thor(corenum, rst_i, clk_i, clk_o, km, nmi_i, irq_i, vec_i, bte_o, cti_o, bl_o, lock_o, resv_o, resv_i, cres_o,`
105			`cyc_o, stb_o, ack_i, err_i, we_o, sel_o, adr_o, dat_i, dat_o);`
106			`parameter DBW = 32; // databus width`
107			`parameter ABW = 32; // address bus width`
108	13	robfinch	`parameter RSTCSEG = 52'h0;`
109	18	robfinch	`parameter RSTPC = 64'hFFFFFFFFFFFC0000;`
110	9	robfinch	`parameter STARTUP_POWER = 16'hFFFF;`
111	18	robfinch	`parameter IMCD = 6'h30;`
112	3	robfinch	`localparam AMSB = ABW-1;`
113			`parameter QENTRIES = 8;`
114			`parameter ALU1BIG = 0;`
115			`parameter RESET1 = 4'd0;`
116			`parameter RESET2 = 4'd1;`
117			`parameter IDLE = 4'd2;`
118			`parameter ICACHE1 = 4'd3;`
119			`parameter DCACHE1 = 4'd4;`
120			`parameter IBUF1 = 4'd5;`
121			`parameter IBUF2 = 4'd6;`
122			`parameter IBUF3 = 4'd7;`
123			`parameter IBUF4 = 4'd8;`
124			`parameter IBUF5 = 4'd9;`
125			`parameter NREGS = 127;`
126			`parameter PF = 4'd0;`
127			`parameter PT = 4'd1;`
128			`parameter PEQ = 4'd2;`
129			`parameter PNE = 4'd3;`
130			`parameter PLE = 4'd4;`
131			`parameter PGT = 4'd5;`
132			`parameter PGE = 4'd6;`
133			`parameter PLT = 4'd7;`
134			`parameter PLEU = 4'd8;`
135			`parameter PGTU = 4'd9;`
136			`parameter PGEU = 4'd10;`
137			`parameter PLTU = 4'd11;`
138			`input [63:0] corenum;`
139			`input rst_i;`
140			`input clk_i;`
141			`output clk_o;`
142			`output km;`
143			`input nmi_i;`
144			`input irq_i;`
145			`input [7:0] vec_i;`
146			`output reg [1:0] bte_o;`
147			`output reg [2:0] cti_o;`
148			`output reg [4:0] bl_o;`
149			`output reg lock_o;`
150			`output reg resv_o;`
151			`input resv_i;`
152			`output reg cres_o;`
153			`output reg cyc_o;`
154			`output reg stb_o;`
155			`input ack_i;`
156			`input err_i;`
157			`output reg we_o;`
158			`output reg [DBW/8-1:0] sel_o;`
159			`output reg [ABW-1:0] adr_o;`
160			`input [DBW-1:0] dat_i;`
161			`output reg [DBW-1:0] dat_o;`
162
163			`integer n,i;`
164	37	robfinch	`reg [1:0] mode;`
165	3	robfinch	`reg [DBW/8-1:0] rsel;`
166			`reg [3:0] cstate;`
167	13	robfinch	`reg [ABW:0] pc; // program counter (virtual)`
168			`wire [ABW-1:0] ppc; // physical pc address`
169	3	robfinch	`reg [ABW-1:0] interrupt_pc; // working register for interrupt pc`
170			`reg [DBW-1:0] vadr; // data virtual address`
171			`reg [3:0] panic; // indexes the message structure`
172			`reg [128:0] message [0:15]; // indexed by panic`
173			`reg [DBW-1:0] cregs [0:15]; // code address registers`
174			`reg [ 3:0] pregs [0:15]; // predicate registers`
175			`ifdef SEGMENTATION
176	13	robfinch	`reg [DBW-1:12] sregs [0:7]; // segment registers`
177	3	robfinch	`reg [DBW-1:12] sregs_lmt [0:7];`
178			`endif
179			`reg [2:0] rrmapno; // register rename map number`
180			`wire ITLBMiss;`
181			`wire DTLBMiss;`
182			`wire uncached;`
183			`wire [DBW-1:0] cdat;`
184			`reg pwe;`
185			`wire [DBW-1:0] pea;`
186			`reg [DBW-1:0] tick;`
187			`reg [DBW-1:0] lc; // loop counter`
188			`reg [DBW-1:0] rfoa0,rfoa1;`
189			`reg [DBW-1:0] rfob0,rfob1;`
190			`reg [DBW-1:0] rfoc0,rfoc1;`
191			`reg [DBW-1:0] rfot0,rfot1;`
192			`reg ic_invalidate,dc_invalidate;`
193			`reg ic_invalidate_line,dc_invalidate_line;`
194			`reg [ABW-1:0] ic_lineno,dc_lineno;`
195			`reg ierr,derr; // err_i during icache load`
196			`wire insnerr; // err_i during icache load`
197			`wire [127:0] insn;`
198			`wire iuncached;`
199			`reg [NREGS:0] rf_v;`
200			`//reg [15:0] pf_v;`
201			`reg im,imb;`
202	13	robfinch	`reg [5:0] imcd;`
203	3	robfinch	`reg fxe;`
204			`reg nmi1,nmi_edge;`
205			`reg StatusHWI;`
206	10	robfinch	`reg StatusDBG;`
207	3	robfinch	`reg [7:0] StatusEXL;`
208			`assign km = StatusHWI \| \|StatusEXL;`
209			`reg [7:0] GM; // register group mask`
210			`reg [7:0] GMB;`
211			`wire [63:0] sr = {32'd0,imb,7'b0,GMB,im,1'b0,km,fxe,4'b0,GM};`
212			`wire int_commit;`
213			`wire int_pending;`
214			`wire sys_commit;`
215	10	robfinch	`wire dbg_commit;`
216	3	robfinch	`ifdef SEGMENTATION
217	13	robfinch	`wire [DBW-1:0] spc = (pc[ABW]==1'b1) ? pc[ABW-1:0] :`
218			`(pc[ABW-1:ABW-4]==4'hF) ? pc[ABW-1:0] : {sregs[3'd7],12'h000} + pc[ABW-1:0];`
219	3	robfinch	`else
220			`wire [DBW-1:0] spc = pc;`
221			`endif
222			`wire [DBW-1:0] ppcp16 = ppc + 64'd16;`
223			`reg [DBW-1:0] string_pc;`
224			`reg stmv_flag;`
225			`reg [7:0] asid;`
226
227			`wire clk;`
228
229			`// Operand registers`
230			`wire take_branch;`
231			`wire take_branch0;`
232			`wire take_branch1;`
233
234			`reg [3:0] rf_source [0:NREGS];`
235			`//reg [3:0] pf_source [15:0];`
236
237			`// instruction queue (ROB)`
238			`reg [7:0] iqentry_v; // entry valid? -- this should be the first bit`
239			`reg iqentry_out [0:7]; // instruction has been issued to an ALU ...`
240			`reg iqentry_done [0:7]; // instruction result valid`
241			`reg [7:0] iqentry_cmt; // commit result to machine state`
242			`reg iqentry_bt [0:7]; // branch-taken (used only for branches)`
243	13	robfinch	`reg iqentry_br [0:7]; // branch instruction decode`
244	3	robfinch	`reg iqentry_agen [0:7]; // memory address is generated`
245			`reg iqentry_mem [0:7]; // touches memory: 1 if LW/SW`
246	10	robfinch	`reg iqentry_ndx [0:7]; // TRUE if indexed memory op`
247			`reg iqentry_cas [0:7];`
248			`reg iqentry_pushpop [0:7];`
249			`reg iqentry_pea [0:7];`
250			`reg iqentry_cmpmv [0:7];`
251	13	robfinch	`reg iqentry_lla [0:7]; // load linear address`
252	10	robfinch	`reg iqentry_tlb [0:7];`
253	3	robfinch	`reg iqentry_jmp [0:7]; // changes control flow: 1 if BEQ/JALR`
254	10	robfinch	`reg iqentry_jmpi [0:7];`
255	13	robfinch	`reg iqentry_sync [0:7]; // sync instruction`
256			`reg iqentry_memsb[0:7];`
257			`reg iqentry_memdb[0:7];`
258	3	robfinch	`reg iqentry_fp [0:7]; // is an floating point operation`
259			`reg iqentry_rfw [0:7]; // writes to register file`
260			`reg [DBW-1:0] iqentry_res [0:7]; // instruction result`
261			`reg [3:0] iqentry_insnsz [0:7]; // the size of the instruction`
262			`reg [3:0] iqentry_cond [0:7]; // predicating condition`
263	9	robfinch	`reg [3:0] iqentry_preg [0:7]; // predicate regno`
264	3	robfinch	`reg [3:0] iqentry_pred [0:7]; // predicate value`
265			`reg iqentry_p_v [0:7]; // predicate is valid`
266			`reg [3:0] iqentry_p_s [0:7]; // predicate source`
267			`reg [7:0] iqentry_op [0:7]; // instruction opcode`
268			`reg [5:0] iqentry_fn [0:7]; // instruction function`
269			`reg [2:0] iqentry_renmapno [0:7]; // register rename map number`
270			`reg [6:0] iqentry_tgt [0:7]; // Rt field or ZERO -- this is the instruction's target (if any)`
271			`reg [DBW-1:0] iqentry_a0 [0:7]; // argument 0 (immediate)`
272			`reg [DBW-1:0] iqentry_a1 [0:7]; // argument 1`
273	10	robfinch	`reg [6:0] iqentry_r1 [0:7];`
274	3	robfinch	`reg iqentry_a1_v [0:7]; // arg1 valid`
275			`reg [3:0] iqentry_a1_s [0:7]; // arg1 source (iq entry # with top bit representing ALU/DRAM bus)`
276	10	robfinch	`reg [6:0] iqentry_r2 [0:7];`
277	3	robfinch	`reg [DBW-1:0] iqentry_a2 [0:7]; // argument 2`
278			`reg iqentry_a2_v [0:7]; // arg2 valid`
279			`reg [3:0] iqentry_a2_s [0:7]; // arg2 source (iq entry # with top bit representing ALU/DRAM bus)`
280	10	robfinch	`reg [6:0] iqentry_r3 [0:7];`
281	3	robfinch	`reg [DBW-1:0] iqentry_a3 [0:7]; // argument 3`
282			`reg iqentry_a3_v [0:7]; // arg3 valid`
283			`reg [3:0] iqentry_a3_s [0:7]; // arg3 source (iq entry # with top bit representing ALU/DRAM bus)`
284	10	robfinch	`reg [6:0] iqentry_rt [0:7];`
285	3	robfinch	`reg [DBW-1:0] iqentry_T [0:7];`
286			`reg iqentry_T_v [0:7];`
287			`reg [3:0] iqentry_T_s [0:7];`
288			`reg [DBW-1:0] iqentry_pc [0:7]; // program counter for this instruction`
289
290	9	robfinch	`reg [7:0] iqentry_source;`
291	3	robfinch	`wire iqentry_imm [0:7];`
292			`wire iqentry_memready [0:7];`
293			`wire iqentry_memopsvalid [0:7];`
294			`reg qstomp;`
295
296			`wire stomp_all;`
297			`reg [7:0] iqentry_fpissue;`
298			`reg [7:0] iqentry_memissue;`
299			`wire iqentry_memissue_head0;`
300			`wire iqentry_memissue_head1;`
301			`wire iqentry_memissue_head2;`
302			`wire iqentry_memissue_head3;`
303			`wire iqentry_memissue_head4;`
304			`wire iqentry_memissue_head5;`
305			`wire iqentry_memissue_head6;`
306			`wire iqentry_memissue_head7;`
307			`wire [7:0] iqentry_stomp;`
308			`reg [7:0] iqentry_issue;`
309			`wire [1:0] iqentry_0_islot;`
310			`wire [1:0] iqentry_1_islot;`
311			`wire [1:0] iqentry_2_islot;`
312			`wire [1:0] iqentry_3_islot;`
313			`wire [1:0] iqentry_4_islot;`
314			`wire [1:0] iqentry_5_islot;`
315			`wire [1:0] iqentry_6_islot;`
316			`wire [1:0] iqentry_7_islot;`
317			`reg [1:0] iqentry_islot[0:7];`
318			`reg [1:0] iqentry_fpislot[0:7];`
319
320			`reg queued1,queued2;`
321			`reg queued3; // for three-way config`
322			`reg allowq;`
323
324			`wire [NREGS:1] livetarget;`
325			`wire [NREGS:1] iqentry_0_livetarget;`
326			`wire [NREGS:1] iqentry_1_livetarget;`
327			`wire [NREGS:1] iqentry_2_livetarget;`
328			`wire [NREGS:1] iqentry_3_livetarget;`
329			`wire [NREGS:1] iqentry_4_livetarget;`
330			`wire [NREGS:1] iqentry_5_livetarget;`
331			`wire [NREGS:1] iqentry_6_livetarget;`
332			`wire [NREGS:1] iqentry_7_livetarget;`
333			`wire [NREGS:1] iqentry_0_latestID;`
334			`wire [NREGS:1] iqentry_1_latestID;`
335			`wire [NREGS:1] iqentry_2_latestID;`
336			`wire [NREGS:1] iqentry_3_latestID;`
337			`wire [NREGS:1] iqentry_4_latestID;`
338			`wire [NREGS:1] iqentry_5_latestID;`
339			`wire [NREGS:1] iqentry_6_latestID;`
340			`wire [NREGS:1] iqentry_7_latestID;`
341			`wire [NREGS:1] iqentry_0_cumulative;`
342			`wire [NREGS:1] iqentry_1_cumulative;`
343			`wire [NREGS:1] iqentry_2_cumulative;`
344			`wire [NREGS:1] iqentry_3_cumulative;`
345			`wire [NREGS:1] iqentry_4_cumulative;`
346			`wire [NREGS:1] iqentry_5_cumulative;`
347			`wire [NREGS:1] iqentry_6_cumulative;`
348			`wire [NREGS:1] iqentry_7_cumulative;`
349
350
351			`reg [2:0] tail0;`
352			`reg [2:0] tail1;`
353			`reg [2:0] tail2; // used only for three-way config`
354			`reg [2:0] head0;`
355			`reg [2:0] head1;`
356			`reg [2:0] head2; // used only to determine memory-access ordering`
357			`reg [2:0] head3; // used only to determine memory-access ordering`
358			`reg [2:0] head4; // used only to determine memory-access ordering`
359			`reg [2:0] head5; // used only to determine memory-access ordering`
360			`reg [2:0] head6; // used only to determine memory-access ordering`
361			`reg [2:0] head7; // used only to determine memory-access ordering`
362			`reg [2:0] headinc;`
363
364			`wire [2:0] missid;`
365			`reg fetchbuf; // determines which pair to read from & write to`
366
367			`reg [63:0] fetchbuf0_instr;`
368			`reg [DBW-1:0] fetchbuf0_pc;`
369			`reg fetchbuf0_v;`
370			`wire fetchbuf0_mem;`
371			`wire fetchbuf0_jmp;`
372			`wire fetchbuf0_fp;`
373			`wire fetchbuf0_rfw;`
374			`wire fetchbuf0_pfw;`
375			`reg [63:0] fetchbuf1_instr;`
376			`reg [DBW-1:0] fetchbuf1_pc;`
377			`reg fetchbuf1_v;`
378			`wire fetchbuf1_mem;`
379			`wire fetchbuf1_jmp;`
380			`wire fetchbuf1_fp;`
381			`wire fetchbuf1_rfw;`
382			`wire fetchbuf1_pfw;`
383			`wire fetchbuf1_bfw;`
384			`reg [63:0] fetchbuf2_instr;`
385			`reg [DBW-1:0] fetchbuf2_pc;`
386			`reg fetchbuf2_v;`
387			`wire fetchbuf2_mem;`
388			`wire fetchbuf2_jmp;`
389			`wire fetchbuf2_fp;`
390			`wire fetchbuf2_rfw;`
391			`wire fetchbuf2_pfw;`
392			`wire fetchbuf2_bfw;`
393
394			`reg [63:0] fetchbufA_instr;`
395			`reg [DBW-1:0] fetchbufA_pc;`
396			`reg fetchbufA_v;`
397			`reg [63:0] fetchbufB_instr;`
398			`reg [DBW-1:0] fetchbufB_pc;`
399			`reg fetchbufB_v;`
400			`reg [63:0] fetchbufC_instr;`
401			`reg [DBW-1:0] fetchbufC_pc;`
402			`reg fetchbufC_v;`
403			`reg [63:0] fetchbufD_instr;`
404			`reg [DBW-1:0] fetchbufD_pc;`
405			`reg fetchbufD_v;`
406
407			`reg did_branchback;`
408			`reg did_branchback0;`
409			`reg did_branchback1;`
410
411			`reg alu0_ld;`
412			`reg alu0_available;`
413			`reg alu0_dataready;`
414			`reg [3:0] alu0_sourceid;`
415			`reg [3:0] alu0_insnsz;`
416			`reg [7:0] alu0_op;`
417			`reg [5:0] alu0_fn;`
418			`reg [3:0] alu0_cond;`
419			`reg alu0_bt;`
420			`reg alu0_cmt;`
421			`reg [DBW-1:0] alu0_argA;`
422			`reg [DBW-1:0] alu0_argB;`
423			`reg [DBW-1:0] alu0_argC;`
424			`reg [DBW-1:0] alu0_argT;`
425			`reg [DBW-1:0] alu0_argI;`
426			`reg [3:0] alu0_pred;`
427			`reg [DBW-1:0] alu0_pc;`
428			`reg [DBW-1:0] alu0_bus;`
429			`reg [3:0] alu0_id;`
430			`wire [3:0] alu0_exc;`
431			`reg alu0_v;`
432			`wire alu0_branchmiss;`
433	13	robfinch	`reg [ABW:0] alu0_misspc;`
434	3	robfinch
435			`reg alu1_ld;`
436			`reg alu1_available;`
437			`reg alu1_dataready;`
438			`reg [3:0] alu1_sourceid;`
439			`reg [3:0] alu1_insnsz;`
440			`reg [7:0] alu1_op;`
441			`reg [5:0] alu1_fn;`
442			`reg [3:0] alu1_cond;`
443			`reg alu1_bt;`
444			`reg alu1_cmt;`
445			`reg [DBW-1:0] alu1_argA;`
446			`reg [DBW-1:0] alu1_argB;`
447			`reg [DBW-1:0] alu1_argC;`
448			`reg [DBW-1:0] alu1_argT;`
449			`reg [DBW-1:0] alu1_argI;`
450			`reg [3:0] alu1_pred;`
451			`reg [DBW-1:0] alu1_pc;`
452			`reg [DBW-1:0] alu1_bus;`
453			`reg [3:0] alu1_id;`
454			`wire [3:0] alu1_exc;`
455			`reg alu1_v;`
456			`wire alu1_branchmiss;`
457	13	robfinch	`reg [ABW:0] alu1_misspc;`
458	3	robfinch
459	10	robfinch	`wire jmpi_miss;`
460			`reg [ABW-1:0] jmpi_misspc;`
461	9	robfinch	`wire mem_stringmissx;`
462			`reg mem_stringmiss;`
463	3	robfinch	`wire branchmiss;`
464	13	robfinch	`wire [ABW:0] misspc;`
465	3	robfinch
466			`ifdef FLOATING_POINT
467			`reg fp0_ld;`
468			`reg fp0_available;`
469			`reg fp0_dataready;`
470			`reg [3:0] fp0_sourceid;`
471			`reg [7:0] fp0_op;`
472			`reg [5:0] fp0_fn;`
473			`reg [3:0] fp0_cond;`
474			`wire fp0_cmt;`
475			`reg fp0_done;`
476			`reg [DBW-1:0] fp0_argA;`
477			`reg [DBW-1:0] fp0_argB;`
478			`reg [DBW-1:0] fp0_argC;`
479			`reg [DBW-1:0] fp0_argI;`
480			`reg [3:0] fp0_pred;`
481			`reg [DBW-1:0] fp0_pc;`
482			`wire [DBW-1:0] fp0_bus;`
483			`wire [3:0] fp0_id;`
484			`wire [7:0] fp0_exc;`
485			`wire fp0_v;`
486			`endif
487
488			`wire dram_avail;`
489			`reg [2:0] dram0; // state of the DRAM request (latency = 4; can have three in pipeline)`
490			`reg [2:0] dram1; // state of the DRAM request (latency = 4; can have three in pipeline)`
491			`reg [2:0] dram2; // state of the DRAM request (latency = 4; can have three in pipeline)`
492			`reg [2:0] tlb_state;`
493			`reg [3:0] tlb_id;`
494			`reg [3:0] tlb_op;`
495			`reg [3:0] tlb_regno;`
496			`reg [8:0] tlb_tgt;`
497			`reg [DBW-1:0] tlb_data;`
498
499			`wire [DBW-1:0] tlb_dato;`
500			`reg dram0_owns_bus;`
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[/] [thor/] [trunk/] [rtl/] [verilog/] [Thor.v] - Blame information for rev 39

Line No.	Rev	Author	Line
1	3	robfinch	`//`
2			`// COPYRIGHT 2000 by Bruce L. Jacob`
3			`// (contact info: http://www.ece.umd.edu/~blj/)`
4			`//`
5			`// You are welcome to use, modify, copy, and/or redistribute this implementation, provided:`
6			`// 1. you share with the author (Bruce Jacob) any changes you make;`
7			`// 2. you properly credit the author (Bruce Jacob) if used within a larger work; and`
8			`// 3. you do not modify, delete, or in any way obscure the implementation's copyright`
9			`// notice or following comments (i.e. the first 3-4 dozen lines of this file).`
10			`//`
11			`// RiSC-16`
12			`//`
13			`// This is an out-of-order implementation of the RiSC-16, a teaching instruction-set used by`
14			`// the author at the University of Maryland, and which is a blatant (but sanctioned) rip-off`
15			`// of the Little Computer (LC-896) developed by Peter Chen at the University of Michigan.`
16			`// The primary differences include the following:`
17			`// 1. a move from 17-bit to 16-bit instructions; and`
18			`// 2. the replacement of the NOP and HALT opcodes by ADDI and LUI ... HALT and NOP are`
19			`// now simply special instances of other instructions: NOP is a do-nothing ADD, and`
20			`// HALT is a subset of JALR.`
21			`//`
22			`// RiSC stands for Ridiculously Simple Computer, which makes sense in the context in which`
23			`// the instruction-set is normally used -- to teach simple organization and architecture to`
24			`// undergraduates who do not yet know how computers work. This implementation was targetted`
25			`// towards more advanced undergraduates doing design & implementation and was intended to`
26			`// demonstrate some high-performance concepts on a small scale -- an 8-entry reorder buffer,`
27			`// eight opcodes, two ALUs, two-way issue, two-way commit, etc. However, the out-of-order`
28			`// core is much more complex than I anticipated, and I hope that its complexity does not`
29			`// obscure its underlying structure. We'll see how well it flies in class ...`
30			`//`
31			`// CAVEAT FREELOADER: This Verilog implementation was developed and debugged in a (somewhat`
32			`// frantic) 2-week period before the start of the Fall 2000 semester. Not surprisingly, it`
33			`// still contains many bugs and some horrible, horrible logic. The logic is also written so`
34			`// as to be debuggable and/or explain its function, rather than to be efficient -- e.g. in`
35			`// several places, signals are over-constrained so that they are easy to read in the debug`
36			`// output ... also, you will see statements like`
37			`//`
38			// if (xyz[`INSTRUCTION_OP] == `BEQ \|\| xyz[`INSTRUCTION_OP] == `SW)
39			`//`
40			`// instead of and/nand combinations of bits ... sorry; can't be helped. Use at your own risk.`