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[/] [openrisc/] [trunk/] [or1200/] [rtl/] [verilog/] [or1200_genpc.v] - Blame information for rev 21

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//////////////////////////////////////////////////////////////////////
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////                                                              ////
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////  OR1200's generate PC                                        ////
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////                                                              ////
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////  This file is part of the OpenRISC 1200 project              ////
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////  http://www.opencores.org/cores/or1k/                        ////
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////                                                              ////
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////  Description                                                 ////
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////  PC, interface to IC.                                        ////
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////                                                              ////
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////  To Do:                                                      ////
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////   - make it smaller and faster                               ////
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////                                                              ////
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////  Author(s):                                                  ////
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////      - Damjan Lampret, lampret@opencores.org                 ////
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////                                                              ////
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//////////////////////////////////////////////////////////////////////
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////                                                              ////
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//// Copyright (C) 2000 Authors and OPENCORES.ORG                 ////
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////                                                              ////
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//// This source file may be used and distributed without         ////
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//// restriction provided that this copyright statement is not    ////
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//// removed from the file and that any derivative work contains  ////
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//// the original copyright notice and the associated disclaimer. ////
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////                                                              ////
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//// This source file is free software; you can redistribute it   ////
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//// and/or modify it under the terms of the GNU Lesser General   ////
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//// Public License as published by the Free Software Foundation; ////
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//// either version 2.1 of the License, or (at your option) any   ////
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//// later version.                                               ////
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////                                                              ////
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//// This source is distributed in the hope that it will be       ////
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//// useful, but WITHOUT ANY WARRANTY; without even the implied   ////
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//// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR      ////
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//// PURPOSE.  See the GNU Lesser General Public License for more ////
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//// details.                                                     ////
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////                                                              ////
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//// You should have received a copy of the GNU Lesser General    ////
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//// Public License along with this source; if not, download it   ////
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//// from http://www.opencores.org/lgpl.shtml                     ////
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////                                                              ////
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//////////////////////////////////////////////////////////////////////
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//
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// CVS Revision History
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//
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// $Log: not supported by cvs2svn $
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// Revision 1.9  2004/04/05 08:29:57  lampret
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// Merged branch_qmem into main tree.
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//
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// Revision 1.7.4.3  2003/12/17 13:43:38  simons
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// Exception prefix configuration changed.
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//
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// Revision 1.7.4.2  2003/12/04 23:44:31  lampret
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// Static exception prefix.
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//
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// Revision 1.7.4.1  2003/07/08 15:36:37  lampret
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// Added embedded memory QMEM.
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//
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// Revision 1.7  2003/04/20 22:23:57  lampret
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// No functional change. Only added customization for exception vectors.
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//
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// Revision 1.6  2002/03/29 15:16:55  lampret
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// Some of the warnings fixed.
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//
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// Revision 1.5  2002/02/11 04:33:17  lampret
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// Speed optimizations (removed duplicate _cyc_ and _stb_). Fixed D/IMMU cache-inhibit attr.
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//
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// Revision 1.4  2002/01/28 01:16:00  lampret
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// Changed 'void' nop-ops instead of insn[0] to use insn[16]. Debug unit stalls the tick timer. Prepared new flag generation for add and and insns. Blocked DC/IC while they are turned off. Fixed I/D MMU SPRs layout except WAYs. TODO: smart IC invalidate, l.j 2 and TLB ways.
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//
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// Revision 1.3  2002/01/18 07:56:00  lampret
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// No more low/high priority interrupts (PICPR removed). Added tick timer exception. Added exception prefix (SR[EPH]). Fixed single-step bug whenreading NPC.
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//
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// Revision 1.2  2002/01/14 06:18:22  lampret
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// Fixed mem2reg bug in FAST implementation. Updated debug unit to work with new genpc/if.
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//
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// Revision 1.1  2002/01/03 08:16:15  lampret
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// New prefixes for RTL files, prefixed module names. Updated cache controllers and MMUs.
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//
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// Revision 1.10  2001/11/20 18:46:15  simons
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// Break point bug fixed
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//
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// Revision 1.9  2001/11/18 09:58:28  lampret
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// Fixed some l.trap typos.
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//
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// Revision 1.8  2001/11/18 08:36:28  lampret
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// For GDB changed single stepping and disabled trap exception.
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//
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// Revision 1.7  2001/10/21 17:57:16  lampret
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// Removed params from generic_XX.v. Added translate_off/on in sprs.v and id.v. Removed spr_addr from dc.v and ic.v. Fixed CR+LF.
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//
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// Revision 1.6  2001/10/14 13:12:09  lampret
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// MP3 version.
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//
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// Revision 1.1.1.1  2001/10/06 10:18:36  igorm
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// no message
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//
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// Revision 1.1  2001/08/09 13:39:33  lampret
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// Major clean-up.
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//
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//
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// synopsys translate_off
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`include "timescale.v"
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// synopsys translate_on
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`include "or1200_defines.v"
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module or1200_genpc(
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        // Clock and reset
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        clk, rst,
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        // External i/f to IC
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        icpu_adr_o, icpu_cycstb_o, icpu_sel_o, icpu_tag_o,
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        icpu_rty_i, icpu_adr_i,
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        // Internal i/f
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        branch_op, except_type, except_prefix,
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        branch_addrofs, lr_restor, flag, taken, except_start,
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        binsn_addr, epcr, spr_dat_i, spr_pc_we, genpc_refetch,
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        genpc_freeze, genpc_stop_prefetch, no_more_dslot
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);
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//
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// I/O
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//
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//
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// Clock and reset
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//
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input                           clk;
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input                           rst;
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//
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// External i/f to IC
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//
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output  [31:0]                   icpu_adr_o;
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output                          icpu_cycstb_o;
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output  [3:0]                    icpu_sel_o;
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output  [3:0]                    icpu_tag_o;
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input                           icpu_rty_i;
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input   [31:0]                   icpu_adr_i;
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//
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// Internal i/f
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//
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input   [`OR1200_BRANCHOP_WIDTH-1:0]     branch_op;
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input   [`OR1200_EXCEPT_WIDTH-1:0]       except_type;
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input                                   except_prefix;
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input   [31:2]                  branch_addrofs;
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input   [31:0]                   lr_restor;
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input                           flag;
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output                          taken;
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input                           except_start;
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input   [31:2]                  binsn_addr;
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input   [31:0]                   epcr;
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input   [31:0]                   spr_dat_i;
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input                           spr_pc_we;
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input                           genpc_refetch;
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input                           genpc_stop_prefetch;
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input                           genpc_freeze;
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input                           no_more_dslot;
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//
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// Internal wires and regs
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//
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reg     [31:2]                  pcreg;
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reg     [31:0]                   pc;
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reg                             taken;  /* Set to in case of jump or taken branch */
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reg                             genpc_refetch_r;
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//
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// Address of insn to be fecthed
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//
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assign icpu_adr_o = !no_more_dslot & !except_start & !spr_pc_we & (icpu_rty_i | genpc_refetch) ? icpu_adr_i : pc;
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// assign icpu_adr_o = !except_start & !spr_pc_we & (icpu_rty_i | genpc_refetch) ? icpu_adr_i : pc;
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//
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// Control access to IC subsystem
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//
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// assign icpu_cycstb_o = !genpc_freeze & !no_more_dslot;
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assign icpu_cycstb_o = !genpc_freeze; // works, except remaining raised cycstb during long load/store
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//assign icpu_cycstb_o = !(genpc_freeze | genpc_refetch & genpc_refetch_r);
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//assign icpu_cycstb_o = !(genpc_freeze | genpc_stop_prefetch);
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assign icpu_sel_o = 4'b1111;
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assign icpu_tag_o = `OR1200_ITAG_NI;
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//
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// genpc_freeze_r
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//
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always @(posedge clk or posedge rst)
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        if (rst)
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                genpc_refetch_r <= #1 1'b0;
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        else if (genpc_refetch)
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                genpc_refetch_r <= #1 1'b1;
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        else
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                genpc_refetch_r <= #1 1'b0;
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//
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// Async calculation of new PC value. This value is used for addressing the IC.
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//
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always @(pcreg or branch_addrofs or binsn_addr or flag or branch_op or except_type
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        or except_start or lr_restor or epcr or spr_pc_we or spr_dat_i or except_prefix) begin
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        casex ({spr_pc_we, except_start, branch_op})    // synopsys parallel_case
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                {2'b00, `OR1200_BRANCHOP_NOP}: begin
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                        pc = {pcreg + 30'd1, 2'b0};
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                        taken = 1'b0;
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                end
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                {2'b00, `OR1200_BRANCHOP_J}: begin
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`ifdef OR1200_VERBOSE
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// synopsys translate_off
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                        $display("%t: BRANCHOP_J: pc <= branch_addrofs %h", $time, branch_addrofs);
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// synopsys translate_on
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`endif
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                        pc = {branch_addrofs, 2'b0};
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                        taken = 1'b1;
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                end
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                {2'b00, `OR1200_BRANCHOP_JR}: begin
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`ifdef OR1200_VERBOSE
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// synopsys translate_off
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                        $display("%t: BRANCHOP_JR: pc <= lr_restor %h", $time, lr_restor);
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// synopsys translate_on
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`endif
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                        pc = lr_restor;
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                        taken = 1'b1;
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                end
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                {2'b00, `OR1200_BRANCHOP_BAL}: begin
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`ifdef OR1200_VERBOSE
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// synopsys translate_off
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                        $display("%t: BRANCHOP_BAL: pc %h = binsn_addr %h + branch_addrofs %h", $time, binsn_addr + branch_addrofs, binsn_addr, branch_addrofs);
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// synopsys translate_on
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`endif
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                        pc = {binsn_addr + branch_addrofs, 2'b0};
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                        taken = 1'b1;
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                end
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                {2'b00, `OR1200_BRANCHOP_BF}:
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                        if (flag) begin
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`ifdef OR1200_VERBOSE
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// synopsys translate_off
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                                $display("%t: BRANCHOP_BF: pc %h = binsn_addr %h + branch_addrofs %h", $time, binsn_addr + branch_addrofs, binsn_addr, branch_addrofs);
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// synopsys translate_on
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`endif
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                                pc = {binsn_addr + branch_addrofs, 2'b0};
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                                taken = 1'b1;
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                        end
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                        else begin
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`ifdef OR1200_VERBOSE
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// synopsys translate_off
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                                $display("%t: BRANCHOP_BF: not taken", $time);
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// synopsys translate_on
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`endif
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                                pc = {pcreg + 30'd1, 2'b0};
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                                taken = 1'b0;
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                        end
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                {2'b00, `OR1200_BRANCHOP_BNF}:
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                        if (flag) begin
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                                pc = {pcreg + 30'd1, 2'b0};
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`ifdef OR1200_VERBOSE
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// synopsys translate_off
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                                $display("%t: BRANCHOP_BNF: not taken", $time);
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// synopsys translate_on
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`endif
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                                taken = 1'b0;
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                        end
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                        else begin
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`ifdef OR1200_VERBOSE
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// synopsys translate_off
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                                $display("%t: BRANCHOP_BNF: pc %h = binsn_addr %h + branch_addrofs %h", $time, binsn_addr + branch_addrofs, binsn_addr, branch_addrofs);
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// synopsys translate_on
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`endif
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                                pc = {binsn_addr + branch_addrofs, 2'b0};
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                                taken = 1'b1;
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                        end
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                {2'b00, `OR1200_BRANCHOP_RFE}: begin
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`ifdef OR1200_VERBOSE
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// synopsys translate_off
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                        $display("%t: BRANCHOP_RFE: pc <= epcr %h", $time, epcr);
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// synopsys translate_on
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`endif
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                        pc = epcr;
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                        taken = 1'b1;
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                end
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                {2'b01, 3'bxxx}: begin
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`ifdef OR1200_VERBOSE
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// synopsys translate_off
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                        $display("Starting exception: %h.", except_type);
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// synopsys translate_on
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`endif
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                        pc = {(except_prefix ? `OR1200_EXCEPT_EPH1_P : `OR1200_EXCEPT_EPH0_P), except_type, `OR1200_EXCEPT_V};
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                        taken = 1'b1;
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                end
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                default: begin
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`ifdef OR1200_VERBOSE
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// synopsys translate_off
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                        $display("l.mtspr writing into PC: %h.", spr_dat_i);
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// synopsys translate_on
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`endif
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                        pc = spr_dat_i;
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                        taken = 1'b0;
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                end
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        endcase
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end
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//
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// PC register
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//
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always @(posedge clk or posedge rst)
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        if (rst)
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//              pcreg <= #1 30'd63;
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                pcreg <= #1 ({(except_prefix ? `OR1200_EXCEPT_EPH1_P : `OR1200_EXCEPT_EPH0_P), `OR1200_EXCEPT_RESET, `OR1200_EXCEPT_V} - 1) >> 2;
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        else if (spr_pc_we)
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                pcreg <= #1 spr_dat_i[31:2];
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        else if (no_more_dslot | except_start | !genpc_freeze & !icpu_rty_i & !genpc_refetch)
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//      else if (except_start | !genpc_freeze & !icpu_rty_i & !genpc_refetch)
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                pcreg <= #1 pc[31:2];
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endmodule

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