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

////                                                              ////

////  OR1200's Load/Store unit                                    ////

////                                                              ////

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

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

////                                                              ////

////  Description                                                 ////

////  Interface between CPU and DC.                               ////

////                                                              ////

////  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 1.3  2002/02/11 04:33:17  lampret

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

//

// Revision 1.2  2002/01/18 07:56:00  lampret

// No more low/high priority interrupts (PICPR removed). Added tick timer exception. Added exception prefix (SR[EPH]). Fixed single-step bug whenreading NPC.

//

// 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  2001/11/30 18:59:47  simons

// *** empty log message ***

//

// Revision 1.8  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 dc.v and ic.v. Fixed CR+LF.

//

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

// MP3 version.

//

// Revision 1.1.1.1  2001/10/06 10:18:36  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"

module or1200_lsu(

        // Clock and reset

        clk, rst,

        // Internal i/f

        addrbase, addrofs, lsu_op, lsu_datain, lsu_dataout, lsu_stall, lsu_unstall,

        du_stall, flushpipe, except_align, except_dtlbmiss, except_dmmufault, except_dbuserr,

        // External i/f to DC

        dcpu_adr_o, dcpu_cycstb_o, dcpu_we_o, dcpu_sel_o, dcpu_tag_o, dcpu_dat_o,

        dcpu_dat_i, dcpu_ack_i, dcpu_rty_i, dcpu_err_i, dcpu_tag_i

);

parameter dw = `OR1200_OPERAND_WIDTH;

parameter aw = `OR1200_REGFILE_ADDR_WIDTH;

//

// I/O

//

//

// Clock and reset

//

input                           clk;

input                           rst;

//

// Internal i/f

//

input   [31:0]                   addrbase;

input   [31:0]                   addrofs;

input   [`OR1200_LSUOP_WIDTH-1:0]        lsu_op;

input   [dw-1:0]         lsu_datain;

output  [dw-1:0]         lsu_dataout;

output                          lsu_stall;

output                          lsu_unstall;

input                           du_stall;

input                           flushpipe;

output                          except_align;

output                          except_dtlbmiss;

output                          except_dmmufault;

output                          except_dbuserr;

//

// External i/f to DC

//

output  [31:0]                   dcpu_adr_o;

output                          dcpu_cycstb_o;

output                          dcpu_we_o;

output  [3:0]                    dcpu_sel_o;

output  [3:0]                    dcpu_tag_o;

output  [31:0]                   dcpu_dat_o;

input   [31:0]                   dcpu_dat_i;

input                           dcpu_ack_i;

input                           dcpu_rty_i;

input                           dcpu_err_i;

input   [3:0]                    dcpu_tag_i;

//

// Internal wires/regs

//

reg     [3:0]                    dcpu_sel_o;

//

// Internal I/F assignments

//

assign lsu_stall = dcpu_rty_i & dcpu_cycstb_o;

assign lsu_unstall = dcpu_ack_i;

assign except_align = ((lsu_op == `OR1200_LSUOP_SH) | (lsu_op == `OR1200_LSUOP_LHZ) | (lsu_op == `OR1200_LSUOP_LHS)) & dcpu_adr_o[0]

                |  ((lsu_op == `OR1200_LSUOP_SW) | (lsu_op == `OR1200_LSUOP_LWZ) | (lsu_op == `OR1200_LSUOP_LWS)) & |dcpu_adr_o[1:0];

assign except_dtlbmiss = dcpu_err_i & (dcpu_tag_i == `OR1200_DTAG_TE);

assign except_dmmufault = dcpu_err_i & (dcpu_tag_i == `OR1200_DTAG_PE);

assign except_dbuserr = dcpu_err_i & (dcpu_tag_i == `OR1200_DTAG_BE);

//

// External I/F assignments

//

assign dcpu_adr_o = addrbase + addrofs;

assign dcpu_cycstb_o = du_stall | lsu_unstall ? 1'b0 : |lsu_op;

assign dcpu_we_o = lsu_op[3];

assign dcpu_tag_o = dcpu_cycstb_o ? `OR1200_DTAG_ND : `OR1200_DTAG_IDLE;

always @(lsu_op or dcpu_adr_o)

        casex({lsu_op, dcpu_adr_o[1:0]})

                {`OR1200_LSUOP_SB, 2'b00} : dcpu_sel_o = 4'b1000;

                {`OR1200_LSUOP_SB, 2'b01} : dcpu_sel_o = 4'b0100;

                {`OR1200_LSUOP_SB, 2'b10} : dcpu_sel_o = 4'b0010;

                {`OR1200_LSUOP_SB, 2'b11} : dcpu_sel_o = 4'b0001;

                {`OR1200_LSUOP_SH, 2'b00} : dcpu_sel_o = 4'b1100;

                {`OR1200_LSUOP_SH, 2'b10} : dcpu_sel_o = 4'b0011;

                {`OR1200_LSUOP_SW, 2'b00} : dcpu_sel_o = 4'b1111;

                {`OR1200_LSUOP_LBZ, 2'b00}, {`OR1200_LSUOP_LBS, 2'b00} : dcpu_sel_o = 4'b1000;

                {`OR1200_LSUOP_LBZ, 2'b01}, {`OR1200_LSUOP_LBS, 2'b01} : dcpu_sel_o = 4'b0100;

                {`OR1200_LSUOP_LBZ, 2'b10}, {`OR1200_LSUOP_LBS, 2'b10} : dcpu_sel_o = 4'b0010;

                {`OR1200_LSUOP_LBZ, 2'b11}, {`OR1200_LSUOP_LBS, 2'b11} : dcpu_sel_o = 4'b0001;

                {`OR1200_LSUOP_LHZ, 2'b00}, {`OR1200_LSUOP_LHS, 2'b00} : dcpu_sel_o = 4'b1100;

                {`OR1200_LSUOP_LHZ, 2'b10}, {`OR1200_LSUOP_LHS, 2'b10} : dcpu_sel_o = 4'b0011;

                {`OR1200_LSUOP_LWZ, 2'b00}, {`OR1200_LSUOP_LWS, 2'b00} : dcpu_sel_o = 4'b1111;

                default : dcpu_sel_o = 4'b0000;

        endcase

//

// Instantiation of Memory-to-regfile aligner

//

or1200_mem2reg or1200_mem2reg(

        .addr(dcpu_adr_o[1:0]),

        .lsu_op(lsu_op),

        .memdata(dcpu_dat_i),

        .regdata(lsu_dataout)

);

//

// Instantiation of Regfile-to-memory aligner

//

or1200_reg2mem or1200_reg2mem(

        .addr(dcpu_adr_o[1:0]),

        .lsu_op(lsu_op),

        .regdata(lsu_datain),

        .memdata(dcpu_dat_o)

);

endmodule