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[/] [apbi2c/] [trunk/] [rtl/] [fifo.v] - Blame information for rev 11

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1 2 redbear
//////////////////////////////////////////////////////////////////
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////
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////
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////    FIFO BLOCK to I2C Core
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////
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////
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////
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//// This file is part of the APB to I2C project
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////
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//// http://www.opencores.org/cores/apbi2c/
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////
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////
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////
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//// Description
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////
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//// Implementation of APB IP core according to
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////
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//// apbi2c_spec IP core specification document.
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////
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////
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////
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//// To Do: This block inst functional yet when you try only write half registers and it didnt go correctly FULL and EMPTY
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////
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////
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////
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////
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////
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//// Author(s): - Felipe Fernandes Da Costa, fefe2560@gmail.com
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////              Ronal Dario Celaya
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////
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///////////////////////////////////////////////////////////////// 
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////
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////
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//// Copyright (C) 2009 Authors and OPENCORES.ORG
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////
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////
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////
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//// This source file may be used and distributed without
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////
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//// restriction provided that this copyright statement is not
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////
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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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////
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//// This source file is free software; you can redistribute it
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////
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//// and/or modify it under the terms of the GNU Lesser General
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////
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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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////
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//// later version.
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////
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////
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////
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//// This source is distributed in the hope that it will be
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////
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//// useful, but WITHOUT ANY WARRANTY; without even the implied
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////
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//// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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////
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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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////
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////
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//// You should have received a copy of the GNU Lesser General
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////
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//// Public License along with this source; if not, download it
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////
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//// from http://www.opencores.org/lgpl.shtml
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////
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////
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///////////////////////////////////////////////////////////////////
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module fifo
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#(
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        parameter integer DWIDTH = 32,
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        parameter integer AWIDTH = 4
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)
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(
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        input clock, reset, wr_en, rd_en,
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        input [DWIDTH-1:0] data_in,
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        output f_full, f_empty,
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        output [DWIDTH-1:0] data_out
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);
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        reg [DWIDTH-1:0] mem [0:2**AWIDTH-1];
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        reg [AWIDTH-1:0] wr_ptr;
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        reg [AWIDTH-1:0] rd_ptr;
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        reg last_was_write;
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        always @ (posedge clock)
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                if (reset)
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                //SYNCHRONOUS RESET
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                begin
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                rd_ptr <= {AWIDTH{1'b0}};
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                wr_ptr <= {AWIDTH{1'b0}};
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                last_was_write <= 1'b1;
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                // NONBLOCKING
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                end
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                else
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                begin
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                if (wr_en )//WRITE OPERATION
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                begin
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                        mem[wr_ptr] <= data_in; //WRITE TO ARRAY
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                        wr_ptr <= wr_ptr + 11'd1;
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                        if(wr_ptr == {AWIDTH{1'b1}})
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                        begin
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                                last_was_write <= 1'b0;
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                        end
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                        rd_ptr <= {AWIDTH{1'b0}};//POINTER GOES TO INITIAL ADDRESSS
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                end
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                else if (rd_en)// READ OPERATION
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                begin
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                        rd_ptr <= rd_ptr + 11'd1;
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                        if(rd_ptr == {AWIDTH{1'b1}})//SIGNAL USED TO NOTICE I2C FIFO IS EMPTY
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                        begin
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                                last_was_write <= 1'b1;
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                                wr_ptr <= {AWIDTH{1'b0}};//POINTER GOES TO INITIAL ADDRESSS
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                        end
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                        else if(wr_ptr != {AWIDTH{1'b0}} && wr_ptr == rd_ptr )//HALF FULL EMPTY CONDITION
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                        begin
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                                last_was_write <= 1'b1;
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                                wr_ptr <= {AWIDTH{1'b0}};//POINTER GOES TO INITIAL ADDRESSS
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                        end
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                end
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                else if(wr_ptr != rd_ptr && !wr_en)//THIS INST TESTED YET
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                begin
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                        last_was_write <= 1'b0;
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                end
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                end
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        assign f_full = (!last_was_write)? 1'b1:1'b0;
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        assign f_empty = (last_was_write)? 1'b1:1'b0;
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        assign data_out = mem[rd_ptr];//WRITE ON OUTPUT
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endmodule

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