pluto_hdl_adi/library/util_var_fifo/util_var_fifo.v

171 lines
5.7 KiB
Verilog

// ***************************************************************************
// ***************************************************************************
// Copyright 2014 - 2017 (c) Analog Devices, Inc. All rights reserved.
//
// In this HDL repository, there are many different and unique modules, consisting
// of various HDL (Verilog or VHDL) components. The individual modules are
// developed independently, and may be accompanied by separate and unique license
// terms.
//
// The user should read each of these license terms, and understand the
// freedoms and responsibilities that he or she has by using this source/core.
//
// This core 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.
//
// Redistribution and use of source or resulting binaries, with or without modification
// of this file, are permitted under one of the following two license terms:
//
// 1. The GNU General Public License version 2 as published by the
// Free Software Foundation, which can be found in the top level directory
// of this repository (LICENSE_GPL2), and also online at:
// <https://www.gnu.org/licenses/old-licenses/gpl-2.0.html>
//
// OR
//
// 2. An ADI specific BSD license, which can be found in the top level directory
// of this repository (LICENSE_ADIBSD), and also on-line at:
// https://github.com/analogdevicesinc/hdl/blob/master/LICENSE_ADIBSD
// This will allow to generate bit files and not release the source code,
// as long as it attaches to an ADI device.
//
// ***************************************************************************
// ***************************************************************************
`timescale 1ns/100ps
module util_var_fifo #(
// parameters
parameter DATA_WIDTH = 32,
parameter ADDRESS_WIDTH = 13
) (
input clk,
input rst,
input [31:0] depth,
input [DATA_WIDTH -1:0] data_in,
input data_in_valid,
output [DATA_WIDTH-1:0] data_out,
output data_out_valid,
output wea_w,
output en_w,
output [ADDRESS_WIDTH-1:0] addr_w,
output [DATA_WIDTH-1:0] din_w,
output en_r,
output [ADDRESS_WIDTH-1:0] addr_r,
input [DATA_WIDTH-1:0] dout_r
);
localparam MAX_DEPTH = (2 ** ADDRESS_WIDTH) - 1;
// internal registers
reg [ADDRESS_WIDTH-1:0] addra = 'd0;
reg [ADDRESS_WIDTH-1:0] addrb = 'd0;
reg [31:0] depth_d1 = 'd0;
reg [DATA_WIDTH-1:0] data_in_d1 = 'd0;
reg [DATA_WIDTH-1:0] data_in_d2 = 'd0;
reg [DATA_WIDTH-1:0] data_in_d3 = 'd0;
reg [DATA_WIDTH-1:0] data_in_d4 = 'd0;
reg data_active = 'd0;
reg fifo_active = 'd0;
reg data_in_valid_d1 = 'd0;
reg data_in_valid_d2 = 'd0;
reg interpolation_on = 'd0;
reg interpolation_on_d1 = 'd0;
reg interpolation_by_2 = 'd0;
reg interpolation_by_2_d1 = 'd0;
reg [DATA_WIDTH-1:0] data_out_d1 = 'd0;
reg [DATA_WIDTH-1:0] data_out_d2 = 'd0;
reg [DATA_WIDTH-1:0] data_out_d3 = 'd0;
// internal signals
wire reset;
wire [DATA_WIDTH-1:0] data_out_s;
wire data_out_valid_s;
assign reset = ((rst == 1'b1) || (depth != depth_d1) || (interpolation_on != interpolation_on_d1) || (interpolation_by_2 != interpolation_by_2_d1)) ? 1 : 0;
assign data_out = fifo_active ? data_out_s : data_in_d4;
assign data_out_valid_s = data_active & data_in_valid;
assign data_out_valid = fifo_active ? data_out_valid_s : data_in_valid;
assign wea_w = data_in_valid & fifo_active;
assign en_w = fifo_active;
assign addr_w = addra;
assign din_w = data_in;
assign en_r = fifo_active;
assign addr_r = addrb;
assign data_out_s = interpolation_on ? (interpolation_by_2 ? data_out_d2 : data_out_d3) : dout_r;
// in case the interpolation is on, the data is available with one sample
// delay. If interpolation is off, the data is available with two or three
// sample delay. Add an extra delay if interpolation is on.
always @(posedge clk) begin
data_in_valid_d1 <= data_in_valid;
data_in_valid_d2 <= data_in_valid_d1;
interpolation_on_d1 = interpolation_on;
interpolation_by_2_d1 = interpolation_by_2;
if (data_in_valid == 1'b1) begin
if (data_in_valid_d1 == 1'b1) begin
interpolation_on <= 1'b0;
end else begin
interpolation_on <= 1'b1;
if (data_in_valid_d2 == 1'b1) begin
interpolation_by_2 <= 1'b1;
end else begin
interpolation_by_2 <= 1'b0;
end
end
end
if(data_out_valid == 1'b1) begin
data_out_d1 <= dout_r;
data_out_d2 <= data_out_d1;
data_out_d3 <= data_out_d2;
end
end
always @(posedge clk) begin
depth_d1 <= depth;
if (depth == 32'h0) begin
fifo_active <= 0;
end else begin
fifo_active <= 1;
end
if (data_in_valid == 1'b1 && fifo_active == 1'b0) begin
data_in_d1 <= data_in;
data_in_d2 <= data_in_d1;
data_in_d3 <= data_in_d2;
data_in_d4 <= data_in_d3;
end
end
always @(posedge clk) begin
if(reset == 1'b1 || fifo_active == 1'b0) begin
addra <= 0;
addrb <= 0;
data_active <= 1'b0;
end else begin
if (data_in_valid == 1'b1) begin
addra <= addra + 1;
if (data_active == 1'b1) begin
addrb <= addrb + 1;
end
end
if (addra > depth || addra > MAX_DEPTH - 2) begin
data_active <= 1'b1;
end
end
end
endmodule