URL
https://opencores.org/ocsvn/versatile_mem_ctrl/versatile_mem_ctrl/trunk
Subversion Repositories versatile_mem_ctrl
Compare Revisions
- This comparison shows the changes necessary to convert path
/
- from Rev 84 to Rev 85
- ↔ Reverse comparison
Rev 84 → Rev 85
/versatile_mem_ctrl/trunk/rtl/verilog/versatile_fifo_async_cmp.v
0,0 → 1,161
////////////////////////////////////////////////////////////////////// |
//// //// |
//// Versatile counter //// |
//// //// |
//// Description //// |
//// Versatile counter, a reconfigurable binary, gray or LFSR //// |
//// counter //// |
//// //// |
//// To Do: //// |
//// - add LFSR with more taps //// |
//// //// |
//// Author(s): //// |
//// - Michael Unneback, unneback@opencores.org //// |
//// ORSoC AB //// |
//// //// |
////////////////////////////////////////////////////////////////////// |
//// //// |
//// Copyright (C) 2009 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 //// |
//// //// |
////////////////////////////////////////////////////////////////////// |
|
module versatile_fifo_async_cmp ( wptr, rptr, fifo_empty, fifo_full, fifo_flag, wclk, rclk, rst ); |
|
parameter ADDR_WIDTH = 4; |
parameter N = ADDR_WIDTH-1; |
|
parameter Q1 = 2'b00; |
parameter Q2 = 2'b01; |
parameter Q3 = 2'b11; |
parameter Q4 = 2'b10; |
|
parameter going_empty = 1'b0; |
parameter going_full = 1'b1; |
|
parameter fifo_flag_value = 4'd4; |
|
input [N:0] wptr, rptr; |
output reg fifo_empty; |
output fifo_full; |
output fifo_flag; |
input wclk, rclk, rst; |
|
wire direction; |
reg direction_set, direction_clr; |
|
wire async_empty, async_full; |
wire fifo_full2; |
reg fifo_empty2; |
reg [N:0] wptr1, wptr2, wptr_bin, rptr_bin; |
reg [N:0] ptr_diff; |
|
integer i; |
|
// direction_set |
always @ (wptr[N:N-1] or rptr[N:N-1]) |
case ({wptr[N:N-1],rptr[N:N-1]}) |
{Q1,Q2} : direction_set <= 1'b1; |
{Q2,Q3} : direction_set <= 1'b1; |
{Q3,Q4} : direction_set <= 1'b1; |
{Q4,Q1} : direction_set <= 1'b1; |
default : direction_set <= 1'b0; |
endcase |
|
// direction_clear |
always @ (wptr[N:N-1] or rptr[N:N-1] or rst) |
if (rst) |
direction_clr <= 1'b1; |
else |
case ({wptr[N:N-1],rptr[N:N-1]}) |
{Q2,Q1} : direction_clr <= 1'b1; |
{Q3,Q2} : direction_clr <= 1'b1; |
{Q4,Q3} : direction_clr <= 1'b1; |
{Q1,Q4} : direction_clr <= 1'b1; |
default : direction_clr <= 1'b0; |
endcase |
|
`ifndef GENERATE_DIRECTION_AS_LATCH |
dff_sr dff_sr_dir( .aclr(direction_clr), .aset(direction_set), .clock(1'b1), .data(1'b1), .q(direction)); |
`endif |
|
`ifdef GENERATE_DIRECTION_AS_LATCH |
always @ (posedge direction_set or posedge direction_clr) |
if (direction_clr) |
direction <= going_empty; |
else |
direction <= going_full; |
`endif |
|
assign async_empty = (wptr == rptr) && (direction==going_empty); |
assign async_full = (wptr == rptr) && (direction==going_full); |
|
dff_sr dff_sr_empty0( .aclr(rst), .aset(async_full), .clock(wclk), .data(async_full), .q(fifo_full2)); |
dff_sr dff_sr_empty1( .aclr(rst), .aset(async_full), .clock(wclk), .data(fifo_full2), .q(fifo_full)); |
|
/* |
always @ (posedge wclk or posedge rst or posedge async_full) |
if (rst) |
{fifo_full, fifo_full2} <= 2'b00; |
else if (async_full) |
{fifo_full, fifo_full2} <= 2'b11; |
else |
{fifo_full, fifo_full2} <= {fifo_full2, async_full}; |
*/ |
always @ (posedge rclk or posedge async_empty) |
if (async_empty) |
{fifo_empty, fifo_empty2} <= 2'b11; |
else |
{fifo_empty,fifo_empty2} <= {fifo_empty2,async_empty}; |
|
|
// Write-domain to read-domain synchronizer |
always @ (posedge rclk or posedge rst) |
if (rst) |
{wptr2,wptr1} <= {4'b0000,4'b0000}; |
else |
{wptr2,wptr1} <= {wptr1,wptr}; |
|
// Gray-to-bin conversion |
always @(wptr2) |
for (i=0;i<4; i=i+1) |
wptr_bin[i] = ^(wptr2>>i); |
|
always @(rptr) |
for (i=0;i<4; i=i+1) |
rptr_bin[i] = ^(rptr>>i); |
|
// Pointer difference |
always @ (wptr_bin or rptr_bin) |
if (wptr_bin > rptr_bin) |
ptr_diff <= wptr_bin - rptr_bin; |
else if (wptr_bin < rptr_bin) |
ptr_diff <= ((5'd16 - rptr_bin) + wptr_bin); |
else |
ptr_diff <= 4'd0; |
|
// Flag |
assign fifo_flag = (ptr_diff >= fifo_flag_value); |
|
|
endmodule // async_comp |