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[/] [wb_lpc/] [trunk/] [rtl/] [verilog/] [wb_regfile.v] - Blame information for rev 20

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1 3 hharte 
//////////////////////////////////////////////////////////////////////
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////                                                              ////
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////  $Id: wb_regfile.v,v 1.3 2008-07-26 19:15:32 hharte Exp $    ////
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////  wb_regfile.v - Small Wishbone register file for testing     ////
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////                                                              ////
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////  This file is part of the Wishbone LPC Bridge project        ////
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////  http://www.opencores.org/projects/wb_lpc/                   ////
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////                                                              ////
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////  Author:                                                     ////
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////      - Howard M. Harte (hharte@opencores.org)                ////
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////                                                              ////
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//////////////////////////////////////////////////////////////////////
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////                                                              ////
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//// Copyright (C) 2008 Howard M. Harte                           ////
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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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module wb_regfile (clk_i, nrst_i, wb_adr_i, wb_dat_o, wb_dat_i, wb_sel_i, wb_we_i,
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                   wb_stb_i, wb_cyc_i, wb_ack_o, wb_err_o, ws_i, datareg0, datareg1);
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    input          clk_i;
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    input          nrst_i;
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    input    [3:0] wb_adr_i;
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    output reg [31:0] wb_dat_o;
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    input   [31:0] wb_dat_i;
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    input    [3:0] wb_sel_i;
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    input          wb_we_i;
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    input          wb_stb_i;
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    input          wb_cyc_i;
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    output reg     wb_ack_o;
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    output         wb_err_o;
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    input    [7:0] ws_i;
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    output  [31:0] datareg0;
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    output  [31:0] datareg1;
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    reg      [7:0] waitstate;
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    //
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    // generate wishbone register bank writes
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    wire wb_acc = wb_cyc_i & wb_stb_i;    // WISHBONE access
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    wire wb_wr  = wb_acc & wb_we_i;       // WISHBONE write access
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    reg [7:0]   datareg0_0;
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    reg [7:0]   datareg0_1;
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    reg [7:0]   datareg0_2;
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    reg [7:0]   datareg0_3;
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    reg [7:0]   datareg1_0;
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    reg [7:0]   datareg1_1;
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    reg [7:0]   datareg1_2;
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    reg [7:0]   datareg1_3;
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    always @(posedge clk_i or negedge nrst_i)
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        if (~nrst_i)                // reset registers
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            begin
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                datareg0_0 <= 8'h00;
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                datareg0_1 <= 8'h01;
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                datareg0_2 <= 8'h02;
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                datareg0_3 <= 8'h03;
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                datareg1_0 <= 8'h10;
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                datareg1_1 <= 8'h11;
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                datareg1_2 <= 8'h12;
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                datareg1_3 <= 8'h13;
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                wb_ack_o <= 1'b0;
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                waitstate <= 4'b0;
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                                         wb_dat_o <= 32'h00000000;
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            end
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        else if(wb_wr)          // wishbone write cycle
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            case (wb_sel_i)
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                4'b0000:
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                    case (wb_adr_i)         // synopsys full_case parallel_case
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                        4'b0000: datareg0_0 <= wb_dat_i[7:0];
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                        4'b0001: datareg0_1 <= wb_dat_i[7:0];
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                        4'b0010: datareg0_2 <= wb_dat_i[7:0];
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                        4'b0011: datareg0_3 <= wb_dat_i[7:0];
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                        4'b0100: datareg1_0 <= wb_dat_i[7:0];
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                        4'b0101: datareg1_1 <= wb_dat_i[7:0];
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                        4'b0110: datareg1_2 <= wb_dat_i[7:0];
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                        4'b0111: datareg1_3 <= wb_dat_i[7:0];
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                    endcase
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                4'b0001:
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                    case (wb_adr_i)         // synopsys full_case parallel_case
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                        4'b0000: datareg0_0 <= wb_dat_i[7:0];
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                        4'b0001: datareg0_1 <= wb_dat_i[7:0];
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                        4'b0010: datareg0_2 <= wb_dat_i[7:0];
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                        4'b0011: datareg0_3 <= wb_dat_i[7:0];
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                        4'b0100: datareg1_0 <= wb_dat_i[7:0];
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                        4'b0101: datareg1_1 <= wb_dat_i[7:0];
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                        4'b0110: datareg1_2 <= wb_dat_i[7:0];
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                        4'b0111: datareg1_3 <= wb_dat_i[7:0];
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                    endcase
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                4'b0011:
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                    {datareg0_1, datareg0_0} <= wb_dat_i[15:0];
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//                  case (wb_adr_i)         // synopsys full_case parallel_case
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//                      3'b000: {datareg0_1, datareg0_0} <= wb_dat_i[15:0];
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//                  endcase
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                4'b1111:
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                    {datareg0_3, datareg0_2, datareg0_1, datareg0_0} <= wb_dat_i[31:0];
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//                  case (wb_adr_i)         // synopsys full_case parallel_case
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//                      3'b000: {datareg0_3, datareg0_2, datareg0_1, datareg0_0} <= wb_dat_i[31:0];
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//                  endcase
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            endcase
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    // generate dat_o
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    always @(posedge clk_i)
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        case (wb_sel_i)
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            4'b0000:
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                case (wb_adr_i)     // synopsys full_case parallel_case
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                    4'b0000: wb_dat_o[7:0] <= datareg0_0;
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                    4'b0001: wb_dat_o[7:0] <= datareg0_1;
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                    4'b0010: wb_dat_o[7:0] <= datareg0_2;
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                    4'b0011: wb_dat_o[7:0] <= datareg0_3;
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                    4'b0100: wb_dat_o[7:0] <= datareg1_0;
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                    4'b0101: wb_dat_o[7:0] <= datareg1_1;
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                    4'b0110: wb_dat_o[7:0] <= datareg1_2;
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                    4'b0111: wb_dat_o[7:0] <= datareg1_3;
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                endcase
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            4'b0001:
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                case (wb_adr_i)     // synopsys full_case parallel_case
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                    4'b0000: wb_dat_o[7:0] <= datareg0_0;
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                    4'b0001: wb_dat_o[7:0] <= datareg0_1;
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                    4'b0010: wb_dat_o[7:0] <= datareg0_2;
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                    4'b0011: wb_dat_o[7:0] <= datareg0_3;
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                    4'b0100: wb_dat_o[7:0] <= datareg1_0;
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                    4'b0101: wb_dat_o[7:0] <= datareg1_1;
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                    4'b0110: wb_dat_o[7:0] <= datareg1_2;
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                    4'b0111: wb_dat_o[7:0] <= datareg1_3;
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                endcase
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            4'b0011:
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                    wb_dat_o[15:0] <= {datareg0_1, datareg0_0};
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            4'b1111:
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                    wb_dat_o[31:0] <= {datareg0_3, datareg0_2, datareg0_1, datareg0_0};
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        endcase
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   // generate ack_o
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    always @(posedge clk_i or negedge nrst_i)
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        if (nrst_i) begin            // not in reset
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            if (ws_i == 0) begin
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                wb_ack_o <= wb_acc & !wb_ack_o;
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                end else
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            if((waitstate == 4'b0) && (ws_i != 0)) begin
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                wb_ack_o <= 1'b0;
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                if(wb_acc) begin
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                    waitstate <= waitstate + 1;
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                end
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            end
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            else begin
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                if(wb_acc) waitstate <= waitstate + 1;
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                if(waitstate == ws_i) begin
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                    if(wb_acc) wb_ack_o <= 1'b1;
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                    waitstate <= 1'b0;
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                end
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            end
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        end
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    assign datareg0 = { datareg0_3, datareg0_2, datareg0_1, datareg0_0 };
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    assign datareg1 = { datareg1_3, datareg1_2, datareg1_1, datareg1_0 };
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    // Generate an error for registers 0x8-0xF
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    assign wb_err_o = wb_ack_o & wb_adr_i[3];
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endmodule

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