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[/] [wb4pb/] [trunk/] [rtl/] [wbm_picoblaze.v] - Blame information for rev 26

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1 2 ste.fis
////////////////////////////////////////////////////////////////////////////////
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// This sourcecode is released under BSD license.
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// Please see http://www.opensource.org/licenses/bsd-license.php for details!
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////////////////////////////////////////////////////////////////////////////////
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//
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// Copyright (c) 2010, Stefan Fischer <Ste.Fis@OpenCores.org>
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without 
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// modification, are permitted provided that the following conditions are met:
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//
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//  * Redistributions of source code must retain the above copyright notice, 
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//    this list of conditions and the following disclaimer.
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//  * Redistributions in binary form must reproduce the above copyright notice,
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//    this list of conditions and the following disclaimer in the documentation
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//    and/or other materials provided with the distribution. 
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//  * Neither the name of the author nor the names of his contributors may be 
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//    used to endorse or promote products derived from this software without 
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//    specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
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// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
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// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE 
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// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
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// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
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// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
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// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
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// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
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// POSSIBILITY OF SUCH DAMAGE.
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//
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////////////////////////////////////////////////////////////////////////////////
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// filename: wbm_picoblaze.v
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// description: synthesizable wishbone master adapter for PicoBlaze (TM),
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//              working together with "wb_wr" and "wb_rd" assembler subroutines
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// todo4user: module should not be changed!
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// version: 0.0.0
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// changelog: - 0.0.0, initial release
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//            - ...
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////////////////////////////////////////////////////////////////////////////////
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module wbm_picoblaze (
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  rst,
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  clk,
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  wbm_cyc_o,
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  wbm_stb_o,
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  wbm_we_o,
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  wbm_adr_o,
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  wbm_dat_m2s_o,
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  wbm_dat_s2m_i,
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  wbm_ack_i,
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  pb_port_id_i,
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  pb_write_strobe_i,
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  pb_out_port_i,
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  pb_read_strobe_i,
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  pb_in_port_o
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);
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  input rst;
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  wire  rst;
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  input clk;
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  wire  clk;
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  output wbm_cyc_o;
69 10 ste.fis
  wire   wbm_cyc_o;
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  output wbm_stb_o;
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  reg    wbm_stb_o;
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  output wbm_we_o;
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  reg    wbm_we_o;
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  output[7:0] wbm_adr_o;
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  reg   [7:0] wbm_adr_o;
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  output[7:0] wbm_dat_m2s_o;
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  reg   [7:0] wbm_dat_m2s_o;
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  input[7:0] wbm_dat_s2m_i;
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  wire [7:0] wbm_dat_s2m_i;
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  input wbm_ack_i;
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  wire  wbm_ack_i;
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  input[7:0] pb_port_id_i;
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  wire [7:0] pb_port_id_i;
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  input pb_write_strobe_i;
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  wire  pb_write_strobe_i;
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  input[7:0] pb_out_port_i;
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  wire [7:0] pb_out_port_i;
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  input pb_read_strobe_i;
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  wire  pb_read_strobe_i;
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  output[7:0] pb_in_port_o;
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  reg   [7:0] pb_in_port_o;
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  reg[7:0] wb_buffer;
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  parameter[7:0] WB_ACK_FLAG = 8'h01;
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  parameter[1:0]
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    S_IDLE = 2'b00,
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    S_WAIT_ON_WB_ACK = 2'b01,
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    S_SOFTWARE_HANDSHAKE = 2'b10,
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    S_SOFTWARE_READ = 2'b11
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  ;
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  reg[1:0] state;
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  assign wbm_cyc_o = wbm_stb_o;
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  always@(posedge clk) begin
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    case(state)
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      S_IDLE:
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        // setting up wishbone address, data and control signals from 
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        // PicoBlaze (TM) signals
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        if (pb_write_strobe_i) begin
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          wbm_stb_o <= 1'b1;
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          wbm_we_o <= 1'b1;
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          wbm_adr_o <= pb_port_id_i;
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          wbm_dat_m2s_o <= pb_out_port_i;
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          state <= S_WAIT_ON_WB_ACK;
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        end else if (pb_read_strobe_i) begin
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          wbm_stb_o <= 1'b1;
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          wbm_we_o <= 1'b0;
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          wbm_adr_o <= pb_port_id_i;
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          state <= S_WAIT_ON_WB_ACK;
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        end
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      S_WAIT_ON_WB_ACK:
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        // waiting on slave peripheral to complete wishbone transfer cycle
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        if (wbm_ack_i) begin
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          wbm_stb_o <= 1'b0;
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          wb_buffer <= wbm_dat_s2m_i;
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          pb_in_port_o <= WB_ACK_FLAG;
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          state <= S_SOFTWARE_HANDSHAKE;
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        end
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      S_SOFTWARE_HANDSHAKE:
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        // software recognition of wishbone handshake
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        if (pb_read_strobe_i)
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          // transfer complete for a write access
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          if (wbm_we_o) begin
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            pb_in_port_o <= 8'h00;
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            state <= S_IDLE;
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          // presenting valid wishbone data to PicoBlaze (TM) port in read 
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          // access
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          end else begin
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            pb_in_port_o <= wb_buffer;
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            state <= S_SOFTWARE_READ;
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          end
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      S_SOFTWARE_READ:
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        // transfer complete for a read access after software recognition of
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        // wishbone data
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        if (pb_read_strobe_i) begin
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          pb_in_port_o <= 8'h00;
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          state <= S_IDLE;
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        end
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      default: ;
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    endcase
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    if (rst) begin
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      wbm_stb_o <= 1'b0;
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      pb_in_port_o <= 8'h00;
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      state <= S_IDLE;
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    end
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  end
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endmodule

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