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<##//////////////////////////////////////////////////////////////////

////                                                             ////

////  Author: Eyal Hochberg                                      ////

////          eyal@provartec.com                                 ////

////                                                             ////

////  Downloaded from: http://www.opencores.org                  ////

/////////////////////////////////////////////////////////////////////

////                                                             ////

//// Copyright (C) 2010 Provartec LTD                            ////

//// www.provartec.com                                           ////

//// info@provartec.com                                          ////

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//// removed from the file and that any derivative work contains ////

//// the original copyright notice and the associated disclaimer.////

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//// 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.////

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//// 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. http://www.gnu.org/licenses/lgpl.html              ////

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//////////////////////////////////////////////////////////////////##>

OUTFILE prgen_fifo.v

ITER DX 1 15

module prgen_fifo(PORTS);

   parameter                  WIDTH      = 8;

   parameter                  DEPTH_FULL = 8;

   parameter                  SINGLE     = DEPTH_FULL == 1;

   parameter                  DEPTH      = SINGLE ? 1 : DEPTH_FULL -1;

   parameter                  DEPTH_BITS =

                              (DEPTH <= EXPR(2^DX)) ? DX :

                              0; //0 is ilegal

   parameter                  LAST_LINE  = DEPTH-1;

   input                      clk;

   input                      reset;

   input                      push;

   input                      pop;

   input [WIDTH-1:0]           din;

   output [WIDTH-1:0]          dout;

   output                     empty;

   output                     full;

   wire                       reg_push;

   wire                       reg_pop;

   wire                       fifo_push;

   wire                       fifo_pop;

   reg [DEPTH-1:0]             fullness_in;

   reg [DEPTH-1:0]             fullness_out;

   reg [DEPTH-1:0]             fullness;

   reg [WIDTH-1:0]             fifo [DEPTH-1:0];

   wire                       fifo_empty;

   wire                       next;

   reg [WIDTH-1:0]             dout;

   reg                        dout_empty;

   reg [DEPTH_BITS-1:0]       ptr_in;

   reg [DEPTH_BITS-1:0]       ptr_out;

   assign                     reg_push  = push & fifo_empty & (dout_empty | pop);

   assign                     reg_pop   = pop & fifo_empty;

   assign                     fifo_push = !SINGLE & push & (~reg_push);

   assign                     fifo_pop  = !SINGLE & pop & (~reg_pop);

   always @(posedge clk or posedge reset)

     if (reset)

       begin

          dout       <= #FFD {WIDTH{1'b0}};

          dout_empty <= #FFD 1'b1;

       end

     else if (reg_push)

       begin

          dout       <= #FFD din;

          dout_empty <= #FFD 1'b0;

       end

     else if (reg_pop)

       begin

          dout       <= #FFD {WIDTH{1'b0}};

          dout_empty <= #FFD 1'b1;

       end

     else if (fifo_pop)

       begin

          dout       <= #FFD fifo[ptr_out];

          dout_empty <= #FFD 1'b0;

       end

   always @(posedge clk or posedge reset)

     if (reset)

       ptr_in <= #FFD {DEPTH_BITS{1'b0}};

     else if (fifo_push)

       ptr_in <= #FFD ptr_in == LAST_LINE ? 0 : ptr_in + 1'b1;

   always @(posedge clk or posedge reset)

     if (reset)

       ptr_out <= #FFD {DEPTH_BITS{1'b0}};

     else if (fifo_pop)

       ptr_out <= #FFD ptr_out == LAST_LINE ? 0 : ptr_out + 1'b1;

   always @(posedge clk)

     if (fifo_push)

       fifo[ptr_in] <= #FFD din;

   always @(*)

     begin

        fullness_in = {DEPTH{1'b0}};

        fullness_in[ptr_in] = fifo_push;

     end

   always @(*)

     begin

        fullness_out = {DEPTH{1'b0}};

        fullness_out[ptr_out] = fifo_pop;

     end

   always @(posedge clk or posedge reset)

     if (reset)

       fullness <= #FFD {DEPTH{1'b0}};

     else if (fifo_push | fifo_pop)

       fullness <= #FFD (fullness & (~fullness_out)) | fullness_in;

   assign next       = |fullness;

   assign fifo_empty = ~next;

   assign empty      = fifo_empty & dout_empty;

   assign full       = SINGLE ? !dout_empty : &fullness;

endmodule