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[/] [openrisc/] [trunk/] [or1200/] [rtl/] [verilog/] [or1200_operandmuxes.v] - Rev 346
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////////////////////////////////////////////////////////////////////// //// //// //// OR1200's register file read operands mux //// //// //// //// This file is part of the OpenRISC 1200 project //// //// http://www.opencores.org/project,or1k //// //// //// //// Description //// //// Mux for two register file read operands. //// //// //// //// 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 //// //// //// ////////////////////////////////////////////////////////////////////// // // $Log: or1200_operandmuxes.v,v $ // Revision 2.0 2010/06/30 11:00:00 ORSoC // Minor update: // Bugs fixed. // synopsys translate_off `include "timescale.v" // synopsys translate_on `include "or1200_defines.v" module or1200_operandmuxes( // Clock and reset clk, rst, // Internal i/f id_freeze, ex_freeze, rf_dataa, rf_datab, ex_forw, wb_forw, simm, sel_a, sel_b, operand_a, operand_b, muxed_a, muxed_b ); parameter width = `OR1200_OPERAND_WIDTH; // // I/O // input clk; input rst; input id_freeze; input ex_freeze; input [width-1:0] rf_dataa; input [width-1:0] rf_datab; input [width-1:0] ex_forw; input [width-1:0] wb_forw; input [width-1:0] simm; input [`OR1200_SEL_WIDTH-1:0] sel_a; input [`OR1200_SEL_WIDTH-1:0] sel_b; output [width-1:0] operand_a; output [width-1:0] operand_b; output [width-1:0] muxed_a; output [width-1:0] muxed_b; // // Internal wires and regs // reg [width-1:0] operand_a; reg [width-1:0] operand_b; reg [width-1:0] muxed_a; reg [width-1:0] muxed_b; reg saved_a; reg saved_b; // // Operand A register // always @(posedge clk or posedge rst) begin if (rst) begin operand_a <= 32'd0; saved_a <= 1'b0; end else if (!ex_freeze && id_freeze && !saved_a) begin operand_a <= muxed_a; saved_a <= 1'b1; end else if (!ex_freeze && !saved_a) begin operand_a <= muxed_a; end else if (!ex_freeze && !id_freeze) saved_a <= 1'b0; end // // Operand B register // always @(posedge clk or posedge rst) begin if (rst) begin operand_b <= 32'd0; saved_b <= 1'b0; end else if (!ex_freeze && id_freeze && !saved_b) begin operand_b <= muxed_b; saved_b <= 1'b1; end else if (!ex_freeze && !saved_b) begin operand_b <= muxed_b; end else if (!ex_freeze && !id_freeze) saved_b <= 1'b0; end // // Forwarding logic for operand A register // always @(ex_forw or wb_forw or rf_dataa or sel_a) begin `ifdef OR1200_ADDITIONAL_SYNOPSYS_DIRECTIVES casex (sel_a) // synopsys parallel_case infer_mux `else casex (sel_a) // synopsys parallel_case `endif `OR1200_SEL_EX_FORW: muxed_a = ex_forw; `OR1200_SEL_WB_FORW: muxed_a = wb_forw; default: muxed_a = rf_dataa; endcase end // // Forwarding logic for operand B register // always @(simm or ex_forw or wb_forw or rf_datab or sel_b) begin `ifdef OR1200_ADDITIONAL_SYNOPSYS_DIRECTIVES casex (sel_b) // synopsys parallel_case infer_mux `else casex (sel_b) // synopsys parallel_case `endif `OR1200_SEL_IMM: muxed_b = simm; `OR1200_SEL_EX_FORW: muxed_b = ex_forw; `OR1200_SEL_WB_FORW: muxed_b = wb_forw; default: muxed_b = rf_datab; endcase end endmodule
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