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//////////////////////////////////////////////////////////////////////

////                                                              ////

////  OR1200's IC FSM                                             ////

////                                                              ////

////  This file is part of the OpenRISC 1200 project              ////

////  http://www.opencores.org/cores/or1k/                        ////

////                                                              ////

////  Description                                                 ////

////  Insn cache state machine                                    ////

////                                                              ////

////  To Do:                                                      ////

////   - make it smaller and faster                               ////

////                                                              ////

////  Author(s):                                                  ////

////      - Damjan Lampret, lampret@opencores.org                 ////

////                                                              ////

//////////////////////////////////////////////////////////////////////

////                                                              ////

//// Copyright (C) 2000 Authors and OPENCORES.ORG                 ////

////                                                              ////

//// This source file may be used and distributed without         ////

//// restriction provided that this copyright statement is not    ////

//// removed from the file and that any derivative work contains  ////

//// the original copyright notice and the associated disclaimer. ////

////                                                              ////

//// 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 2.1 of the License, or (at your option) any   ////

//// later version.                                               ////

////                                                              ////

//// This source 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 Lesser General Public License for more ////

//// details.                                                     ////

////                                                              ////

//// You should have received a copy of the GNU Lesser General    ////

//// Public License along with this source; if not, download it   ////

//// from http://www.opencores.org/lgpl.shtml                     ////

////                                                              ////

//////////////////////////////////////////////////////////////////////

//

// CVS Revision History

//

// $Log: not supported by cvs2svn $

// Revision 1.9  2004/04/05 08:29:57  lampret

// Merged branch_qmem into main tree.

//

// Revision 1.8.4.1  2003/07/08 15:36:37  lampret

// Added embedded memory QMEM.

//

// Revision 1.8  2003/06/06 02:54:47  lampret

// When OR1200_NO_IMMU and OR1200_NO_IC are not both defined or undefined at the same time, results in a IC bug. Fixed.

//

// Revision 1.7  2002/03/29 15:16:55  lampret

// Some of the warnings fixed.

//

// Revision 1.6  2002/03/28 19:10:40  lampret

// Optimized cache controller FSM.

//

// Revision 1.1.1.1  2002/03/21 16:55:45  lampret

// First import of the "new" XESS XSV environment.

//

//

// Revision 1.5  2002/02/11 04:33:17  lampret

// Speed optimizations (removed duplicate _cyc_ and _stb_). Fixed D/IMMU cache-inhibit attr.

//

// Revision 1.4  2002/02/01 19:56:54  lampret

// Fixed combinational loops.

//

// Revision 1.3  2002/01/28 01:16:00  lampret

// 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.

//

// Revision 1.2  2002/01/14 06:18:22  lampret

// Fixed mem2reg bug in FAST implementation. Updated debug unit to work with new genpc/if.

//

// Revision 1.1  2002/01/03 08:16:15  lampret

// New prefixes for RTL files, prefixed module names. Updated cache controllers and MMUs.

//

// Revision 1.9  2001/10/21 17:57:16  lampret

// Removed params from generic_XX.v. Added translate_off/on in sprs.v and id.v. Removed spr_addr from ic.v and ic.v. Fixed CR+LF.

//

// Revision 1.8  2001/10/19 23:28:46  lampret

// Fixed some synthesis warnings. Configured with caches and MMUs.

//

// Revision 1.7  2001/10/14 13:12:09  lampret

// MP3 version.

//

// Revision 1.1.1.1  2001/10/06 10:18:35  igorm

// no message

//

// Revision 1.2  2001/08/09 13:39:33  lampret

// Major clean-up.

//

// Revision 1.1  2001/07/20 00:46:03  lampret

// Development version of RTL. Libraries are missing.

//

//

// synopsys translate_off

`include "timescale.v"

// synopsys translate_on

`include "or1200_defines.v"

`define OR1200_ICFSM_IDLE       2'd0

`define OR1200_ICFSM_CFETCH     2'd1

`define OR1200_ICFSM_LREFILL3   2'd2

`define OR1200_ICFSM_IFETCH     2'd3

//

// Data cache FSM for cache line of 16 bytes (4x singleword)

//

module or1200_ic_fsm(

        // Clock and reset

        clk, rst,

        // Internal i/f to top level IC

        ic_en, icqmem_cycstb_i, icqmem_ci_i,

        tagcomp_miss, biudata_valid, biudata_error, start_addr, saved_addr,

        icram_we, biu_read, first_hit_ack, first_miss_ack, first_miss_err,

        burst, tag_we

);

//

// I/O

//

input                           clk;

input                           rst;

input                           ic_en;

input                           icqmem_cycstb_i;

input                           icqmem_ci_i;

input                           tagcomp_miss;

input                           biudata_valid;

input                           biudata_error;

input   [31:0]                   start_addr;

output  [31:0]                   saved_addr;

output  [3:0]                    icram_we;

output                          biu_read;

output                          first_hit_ack;

output                          first_miss_ack;

output                          first_miss_err;

output                          burst;

output                          tag_we;

//

// Internal wires and regs

//

reg     [31:0]                   saved_addr_r;

reg     [1:0]                    state;

reg     [2:0]                    cnt;

reg                             hitmiss_eval;

reg                             load;

reg                             cache_inhibit;

//

// Generate of ICRAM write enables

//

assign icram_we = {4{biu_read & biudata_valid & !cache_inhibit}};

assign tag_we = biu_read & biudata_valid & !cache_inhibit;

//

// BIU read and write

//

assign biu_read = (hitmiss_eval & tagcomp_miss) | (!hitmiss_eval & load);

//assign saved_addr = hitmiss_eval ? start_addr : saved_addr_r;

assign saved_addr = saved_addr_r;

//

// Assert for cache hit first word ready

// Assert for cache miss first word stored/loaded OK

// Assert for cache miss first word stored/loaded with an error

//

assign first_hit_ack = (state == `OR1200_ICFSM_CFETCH) & hitmiss_eval & !tagcomp_miss & !cache_inhibit & !icqmem_ci_i;

assign first_miss_ack = (state == `OR1200_ICFSM_CFETCH) & biudata_valid;

assign first_miss_err = (state == `OR1200_ICFSM_CFETCH) & biudata_error;

//

// Assert burst when doing reload of complete cache line

//

assign burst = (state == `OR1200_ICFSM_CFETCH) & tagcomp_miss & !cache_inhibit

                | (state == `OR1200_ICFSM_LREFILL3);

//

// Main IC FSM

//

always @(posedge clk or posedge rst) begin

        if (rst) begin

                state <= #1 `OR1200_ICFSM_IDLE;

                saved_addr_r <= #1 32'b0;

                hitmiss_eval <= #1 1'b0;

                load <= #1 1'b0;

                cnt <= #1 3'b000;

                cache_inhibit <= #1 1'b0;

        end

        else

        case (state)    // synopsys parallel_case

                `OR1200_ICFSM_IDLE :

                        if (ic_en & icqmem_cycstb_i) begin              // fetch

                                state <= #1 `OR1200_ICFSM_CFETCH;

                                saved_addr_r <= #1 start_addr;

                                hitmiss_eval <= #1 1'b1;

                                load <= #1 1'b1;

                                cache_inhibit <= #1 1'b0;

                        end

                        else begin                                                      // idle

                                hitmiss_eval <= #1 1'b0;

                                load <= #1 1'b0;

                                cache_inhibit <= #1 1'b0;

                        end

                `OR1200_ICFSM_CFETCH: begin     // fetch

                        if (icqmem_cycstb_i & icqmem_ci_i)

                                cache_inhibit <= #1 1'b1;

                        if (hitmiss_eval)

                                saved_addr_r[31:13] <= #1 start_addr[31:13];

                        if ((!ic_en) ||

                            (hitmiss_eval & !icqmem_cycstb_i) ||        // fetch aborted (usually caused by IMMU)

                            (biudata_error) ||                                          // fetch terminated with an error

                            (cache_inhibit & biudata_valid)) begin      // fetch from cache-inhibited page

                                state <= #1 `OR1200_ICFSM_IDLE;

                                hitmiss_eval <= #1 1'b0;

                                load <= #1 1'b0;

                                cache_inhibit <= #1 1'b0;

                        end

                        else if (tagcomp_miss & biudata_valid) begin    // fetch missed, finish current external fetch and refill

                                state <= #1 `OR1200_ICFSM_LREFILL3;

                                saved_addr_r[3:2] <= #1 saved_addr_r[3:2] + 1'd1;

                                hitmiss_eval <= #1 1'b0;

                                cnt <= #1 `OR1200_ICLS-2;

                                cache_inhibit <= #1 1'b0;

                        end

                        else if (!tagcomp_miss & !icqmem_ci_i) begin    // fetch hit, finish immediately

                                saved_addr_r <= #1 start_addr;

                                cache_inhibit <= #1 1'b0;

                        end

                        else if (!icqmem_cycstb_i) begin        // fetch aborted (usually caused by exception)

                                state <= #1 `OR1200_ICFSM_IDLE;

                                hitmiss_eval <= #1 1'b0;

                                load <= #1 1'b0;

                                cache_inhibit <= #1 1'b0;

                        end

                        else                                            // fetch in-progress

                                hitmiss_eval <= #1 1'b0;

                end

                `OR1200_ICFSM_LREFILL3 : begin

                        if (biudata_valid && (|cnt)) begin              // refill ack, more fetchs to come

                                cnt <= #1 cnt - 3'd1;

                                saved_addr_r[3:2] <= #1 saved_addr_r[3:2] + 1'd1;

                        end

                        else if (biudata_valid) begin                   // last fetch of line refill

                                state <= #1 `OR1200_ICFSM_IDLE;

                                saved_addr_r <= #1 start_addr;

                                hitmiss_eval <= #1 1'b0;

                                load <= #1 1'b0;

                        end

                end

                default:

                        state <= #1 `OR1200_ICFSM_IDLE;

        endcase

end

endmodule