Subversion Repositories srdydrdy_lib

//----------------------------------------------------------------------

// Srdy/Drdy output block

//

// Halts timing on all signals except ic_drdy

// ic_drdy is a combinatorial path from p_drdy

//

// Naming convention: c = consumer, p = producer, i = internal interface

//----------------------------------------------------------------------

// Author: Guy Hutchison

//

// This block is uncopyrighted and released into the public domain.

//----------------------------------------------------------------------

// Clocking statement for synchronous blocks.  Default is for

// posedge clocking and positive async reset

`ifndef SDLIB_CLOCKING

 `define SDLIB_CLOCKING posedge clk or posedge reset

`endif

// delay unit for nonblocking assigns, default is to #1

`ifndef SDLIB_DELAY

 `define SDLIB_DELAY #1

`endif

module sd_output

  #(parameter width = 8)

  (

   input              clk,

   input              reset,

   input              ic_srdy,

   output reg         ic_drdy,

   input [width-1:0]  ic_data,

   output reg         p_srdy,

   input              p_drdy,

   output reg [width-1:0] p_data

   );

  reg     load;   // true when data will be loaded into p_data

  reg     drain;  // true when data will be emptied from p_data

  reg     hold;   // true when data will be held in p_data

  reg     nxt_p_srdy;

  always @*

    begin

      drain = p_srdy & p_drdy;

      hold  = p_srdy & !p_drdy;

      ic_drdy = drain | !p_srdy;

      load  = ic_srdy & ic_drdy;

      nxt_p_srdy = load | hold;

    end

  always @(`SDLIB_CLOCKING)

    begin

      if (reset)

        begin

          p_srdy <= `SDLIB_DELAY 0;

        end

      else

        begin

          p_srdy <= `SDLIB_DELAY nxt_p_srdy;

        end // else: !if(reset)

    end // always @ (posedge clk)

  always @(posedge clk)

    if (load)

      p_data <= `SDLIB_DELAY ic_data;

endmodule // it_output