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[/] [8051/] [tags/] [rel_12/] [rtl/] [verilog/] [oc8051_alu_src_sel.v] - Blame information for rev 81

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1 81 simont
//////////////////////////////////////////////////////////////////////
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////                                                              ////
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////  8051 alu source select module                               ////
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////                                                              ////
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////  This file is part of the 8051 cores project                 ////
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////  http://www.opencores.org/cores/8051/                        ////
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////                                                              ////
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////  Description                                                 ////
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////   Multiplexer wiht whitch we select data on alu sources      ////
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////                                                              ////
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////  To Do:                                                      ////
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////   nothing                                                    ////
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////                                                              ////
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////  Author(s):                                                  ////
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////      - Simon Teran, simont@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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//
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//
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// synopsys translate_off
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`include "oc8051_timescale.v"
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// synopsys translate_on
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`include "oc8051_defines.v"
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module oc8051_alu_src_sel (clk, rst, rd, sel1, sel2, sel3,
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                     acc, ram, pc, dptr,
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                     op1, op2, op3,
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                     src1, src2, src3);
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input clk, rst, rd, sel3;
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input [2:0] sel1, sel2;
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input [7:0] acc, ram;
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input [15:0] dptr;
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input [15:0] pc;
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input [7:0] op1, op2, op3;
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output [7:0] src1, src2, src3;
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reg [7:0] src1, src2, src3;
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reg [7:0] op1_r, op2_r, op3_r;
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reg [15:0] pc_r;
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///////
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//
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// src1
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//
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///////
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always @(sel1 or op1_r or op2_r or op3_r or pc_r or acc or ram)
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begin
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  case (sel1)
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    `OC8051_AS1_RAM: src1 = ram;
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    `OC8051_AS1_ACC: src1 = acc;
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    `OC8051_AS1_OP1: src1 = op1_r;
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    `OC8051_AS1_OP2: src1 = op2_r;
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    `OC8051_AS1_OP3: src1 = op3_r;
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    `OC8051_AS1_PCH: src1 = pc_r[15:8];
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    `OC8051_AS1_PCL: src1 = pc_r[7:0];
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    default: src1 = 8'h00;
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  endcase
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end
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///////
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//
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// src2
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//
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///////
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always @(sel2 or op2_r or pc_r or acc or ram or op1_r or pc)
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begin
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  case (sel2)
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    `OC8051_AS2_ACC: src2= acc;
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    `OC8051_AS2_ZERO: src2= 8'h00;
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    `OC8051_AS2_RAM: src2= ram;
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    `OC8051_AS2_OP2: src2= op2_r;
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    `OC8051_AS2_PCL: src2= pc_r[7:0];
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    default: src2= 8'h00;
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  endcase
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end
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///////
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//
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// src3
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//
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///////
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always @(sel3 or pc[15:8] or dptr[15:8] or op1_r)
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begin
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  case (sel3)
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    `OC8051_AS3_DP:   src3= dptr[15:8];
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    `OC8051_AS3_PC:   src3= pc[15:8];
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    default: src3= 16'h0;
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  endcase
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end
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always @(posedge clk or posedge rst)
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  if (rst) begin
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    op1_r <= #1 8'h00;
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    op2_r <= #1 8'h00;
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    op3_r <= #1 8'h00;
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  end else begin
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    op1_r <= #1 op1;
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    op2_r <= #1 op2;
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    op3_r <= #1 op3;
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  end
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always @(posedge clk or posedge rst)
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  if (rst) begin
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    pc_r <= #1 16'h0;
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  end else if (rd) begin
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    pc_r <= #1 pc;
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  end
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endmodule

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