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[/] [sdr_ctrl/] [trunk/] [rtl/] [core/] [sdrc_bs_convert.v] - Rev 3

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/*********************************************************************
 
  SDRAM Controller buswidth converter                                  
 
  This file is part of the sdram controller project           
  http://www.opencores.org/cores/sdr_ctrl/                    
 
  Description: SDRAM Controller Buswidth converter
 
  This module does write/read data transalation between
     application data to SDRAM bus width
 
  To Do:                                                      
    nothing                                                   
 
  Author(s):                                                  
      - Dinesh Annayya, dinesha@opencores.org                 
  Version  :  1.0  - 8th Jan 2012
 
 
 
 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                     
 
*******************************************************************/
 
`include "sdrc.def"
module sdrc_bs_convert (
                    clk,
                    reset_n,
                    sdr_width,
 
                    app_req_addr,
                    app_req_addr_int,
                    app_req_len,
                    app_req_len_int,
                    app_req,
                    app_req_int,
                    app_req_dma_last,
                    app_req_dma_last_int,
                    app_req_wr_n,
                    app_req_ack,
                    app_req_ack_int,
 
                    app_wr_data,
                    app_wr_data_int,
                    app_wr_en_n,
                    app_wr_en_n_int,
                    app_wr_next_int,
                    app_wr_next,
 
                    app_rd_data_int,
                    app_rd_data,
                    app_rd_valid_int,
                    app_rd_valid
		);
parameter  APP_AW   = 30;  // Application Address Width
parameter  APP_DW   = 32;  // Application Data Width 
parameter  APP_BW   = 4;   // Application Byte Width
parameter  APP_RW   = 9;   // Application Request Width
 
parameter  SDR_DW   = 16;  // SDR Data Width 
parameter  SDR_BW   = 2;   // SDR Byte Width
 
input                    clk;
input                    reset_n ;
input                    sdr_width;
 
input [APP_AW-1:0]       app_req_addr;
output [APP_AW:0]        app_req_addr_int;
input  [APP_RW-1:0]      app_req_len ;
output [APP_RW-1:0]      app_req_len_int; 
input                    app_req_wr_n;
input                    app_req;
output                   app_req_int;
input                    app_req_dma_last;
output                   app_req_dma_last_int;
input                    app_req_ack_int;
output                   app_req_ack;
 
input  [APP_DW-1:0]      app_wr_data;
output [SDR_DW-1:0]      app_wr_data_int;
input  [APP_BW-1:0]      app_wr_en_n;
output [SDR_BW-1:0]      app_wr_en_n_int;
input                    app_wr_next_int;
output                   app_wr_next;
 
input [SDR_DW-1:0]       app_rd_data_int;
output [APP_DW-1:0]      app_rd_data;
input                    app_rd_valid_int;
output                   app_rd_valid;
 
reg [APP_AW:0]           app_req_addr_int;
reg [APP_RW-1:0]         app_req_len_int;
 
reg                      app_req_dma_last_int;
reg                      app_req_int;
reg                      app_req_ack;
 
reg [APP_DW-1:0]         app_rd_data;
reg                      app_rd_valid;
reg [SDR_DW-1:0]         app_wr_data_int;
reg [SDR_BW-1:0]         app_wr_en_n_int;
reg                      app_wr_next;
 
reg                      lcl_rd_valid;
reg                      lcl_wr_next;
reg [15:0]               saved_rd_data;
reg                      save_lower;
reg                      upper_word;
reg                      write_upper;
reg [7:0]                rd_xfr_count;
reg [7:0]                wr_xfr_count;
 
reg [3:0]               rd_state,next_rd_state;
reg [3:0]               wr_state,next_wr_state;
 
parameter            SDR16_IDLE = 0,
                     SDR16_RD_LO = 1,
                     SDR16_RD_HI = 2,
                     SDR16_WR_LO = 3,
                     SDR16_WR_HI = 4;
wire                  ok_to_req;                   
 
assign ok_to_req = ((wr_state == SDR16_IDLE) && (rd_state == SDR16_IDLE));
 
always @(*) begin
        if(!sdr_width) // 32 Bit SDR Mode
          begin
            app_req_addr_int = {1'b0,app_req_addr};
            app_req_len_int = app_req_len;
            app_wr_data_int = app_wr_data;
            app_wr_en_n_int = app_wr_en_n;
            app_req_dma_last_int = app_req_dma_last;
            app_req_int = app_req;
            app_wr_next = app_wr_next_int;
            app_rd_data = app_rd_data_int;
            app_rd_valid = app_rd_valid_int;
            app_req_ack = app_req_ack_int;
          end
        else   // 16 Bit SDR Mode
          begin
           // Changed the address and length to match the 16 bit SDR Mode
            app_req_addr_int = {app_req_addr,1'b0};
            app_req_len_int = {app_req_len,1'b0};
            app_req_dma_last_int = app_req_dma_last;
            app_req_int = app_req && ok_to_req;
            app_req_ack = app_req_ack_int;
            app_wr_next = lcl_wr_next;
            app_rd_valid = lcl_rd_valid;
            if(write_upper)
              begin
                app_wr_en_n_int = app_wr_en_n[3:2];
                app_wr_data_int = app_wr_data[31:16];
              end
            else
              begin
                app_wr_en_n_int = app_wr_en_n[1:0];
                app_wr_data_int = app_wr_data[15:0];
              end
 
            app_rd_data = {app_rd_data_int[15:0],saved_rd_data};
          end
        end
 
//
// WRITES
//
always @(*) begin
 
        lcl_wr_next = 1'b0;
        upper_word = 1'b0;
        next_wr_state = wr_state;
 
        case(wr_state)
          SDR16_IDLE:
            begin
              if(app_req_ack_int && sdr_width)
                begin
                  if(~app_req_wr_n)
                    begin
                      next_wr_state = SDR16_WR_LO;
                    end
                end
              else
                begin
                  next_wr_state = SDR16_IDLE;
                end
            end
          SDR16_WR_LO:
            begin
              if(app_wr_next)
                begin
                  upper_word = 1'b1;
                  next_wr_state = SDR16_WR_HI;
                end
             end
          SDR16_WR_HI:
            begin
              if(app_wr_next_int)
                if(~(|wr_xfr_count))
                  begin
                    lcl_wr_next = 1'b1;
                    next_wr_state = SDR16_IDLE;
                  end
                else
                  begin
                    lcl_wr_next = 1'b1;
                    next_wr_state = SDR16_WR_LO;
                  end
            end
          default:
            begin
              next_wr_state = SDR16_IDLE;
            end
        endcase
        end
//
// READS
//
always @(*) begin
 
        lcl_rd_valid = 1'b0;
        save_lower = 1'b0;
        next_rd_state = rd_state;
 
        case(rd_state)
          SDR16_IDLE:
            begin
              if(app_req_ack_int && sdr_width)
                begin
                  if(app_req_wr_n)
                    begin
                      next_rd_state = SDR16_RD_LO;
                    end
                end
              else
                begin
                  next_rd_state = SDR16_IDLE;
                end
            end
          SDR16_RD_LO:
            begin
              if(app_rd_valid_int)
                begin
                  save_lower = 1'b1;
                  next_rd_state = SDR16_RD_HI;
                end
            end
          SDR16_RD_HI:
            begin
              if(app_rd_valid_int)
                if(~(|rd_xfr_count))
                  begin
                    lcl_rd_valid = 1'b1;
                    next_rd_state = SDR16_IDLE;
                  end
                else
                  begin
                    lcl_rd_valid = 1'b1;
                    next_rd_state = SDR16_RD_LO;
                  end
            end
          default:
            begin
              next_rd_state = SDR16_IDLE;
            end
        endcase
        end
 
reg lcl_mc_req_wr_n;
 
always @(posedge clk)
  begin
    if(!reset_n)
      begin
        rd_xfr_count <= 8'b0;
        wr_xfr_count <= 8'b0;
        lcl_mc_req_wr_n <= 1'b1;
      end
    else
      begin
        if(app_req_ack) begin
           wr_xfr_count    <= app_req_len - 1'b1;
           rd_xfr_count    <= app_req_len - 1'b1;
           lcl_mc_req_wr_n <= app_req_wr_n;
        end
        else if((lcl_wr_next & !lcl_mc_req_wr_n) || (lcl_rd_valid & lcl_mc_req_wr_n)) begin
           wr_xfr_count <= wr_xfr_count - 1'b1;
           rd_xfr_count <= rd_xfr_count - 1'b1;
        end
      end
  end
//
//
always @(posedge clk)
  begin
    if(!reset_n)
      begin
        rd_state      <= SDR16_IDLE;
        wr_state      <= SDR16_IDLE;
        saved_rd_data <= 16'b0;
        write_upper   <= 1'b0;
      end
    else
      begin
        rd_state        <= next_rd_state;
        wr_state        <= next_wr_state;
        if(save_lower)
          saved_rd_data <= app_rd_data_int[15:0];
        write_upper <= upper_word;
      end
  end
 
endmodule // sdr_bs_convert
 

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