pluto_hdl_adi/library/common/ad_upack.v

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// ***************************************************************************
// ***************************************************************************
// Copyright 2014 - 2022 (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
// Unpacker:
// - unpack O_W number of data units from I_W number of data units
// - data unit defined in bits by UNIT_W e.g 8 is a byte
//
// Constraints:
// - O_W < I_W
// - LATENCY 1
// - no backpressure
//
// Data format:
// idata [U(I_W-1) .... U(0)]
// odata [U(O_W-1) .... U(0)]
//
// e.g
// I_W = 6
// O_W = 4
// UNIT_W = 8
//
// idata : [B5,B4,B3,B2,B1,B0],[B11,B10,B9,B8,B7,B6]
// odata : [B3,B2,B1,B0],[B7,B6,B5,B4],[B11,B10,B9,B8]
//
module ad_upack #(
parameter I_W = 4,
parameter O_W = 3,
parameter UNIT_W = 8,
parameter O_REG = 1
) (
input clk,
input reset,
input [I_W*UNIT_W-1:0] idata,
input ivalid,
output iready,
output reg [O_W*UNIT_W-1:0] odata = 'h0,
output reg ovalid = 'b0
);
// The Width of the shift reg is an integer multiple of output data width
localparam SH_W = ((I_W/O_W) + ((I_W%O_W) > 0) + ((O_W % (I_W - ((I_W/O_W)*O_W) + ((I_W%O_W) == 0))) > 0))*O_W;
// The Step of the algorithm is the greatest common divisor of I_W and O_W
localparam STEP = gcd(I_W, O_W);
localparam LATENCY = 1; // Minimum input latency from iready to ivalid
integer i;
reg [SH_W*UNIT_W-1:0] idata_sh;
reg [SH_W*UNIT_W-1:0] idata_d = 'h0;
reg [SH_W*UNIT_W-1:0] idata_d_nx;
reg [SH_W-1:0] in_use = 'h0;
reg [SH_W-1:0] inmask;
wire [SH_W-1:0] out_mask = {O_W{1'b1}};
wire [SH_W-1:0] in_use_nx;
wire [SH_W-1:0] unit_valid;
wire [O_W*UNIT_W-1:0] odata_s;
wire ovalid_s;
function [31:0] gcd;
input [31:0] a;
input [31:0] b;
begin
while (a != b) begin
if (a > b) begin
a = a-b;
end else begin
b = b-a;
end
end
gcd = a;
end
endfunction
assign unit_valid = (in_use | inmask);
assign in_use_nx = unit_valid >> O_W;
always @(posedge clk) begin
if (reset) begin
in_use <= 'h0;
end else if (ovalid_s) begin
in_use <= in_use_nx;
end
end
always @(*) begin
inmask = {I_W{ivalid}};
for (i = STEP; i < O_W; i=i+STEP) begin
if (in_use[i-1]) begin
inmask = {I_W{ivalid}} << i;
end
end
end
always @(*) begin
idata_d_nx = idata_d;
if (ivalid) begin
idata_d_nx = {{(SH_W-I_W)*UNIT_W{1'b0}},idata};
for (i = STEP; i < O_W; i=i+STEP) begin
if (in_use[i-1]) begin
idata_d_nx = (idata << UNIT_W*i) | idata_d;
end
end
end
end
always @(posedge clk) begin
if (ovalid_s) begin
idata_d <= idata_d_nx >> O_W*UNIT_W;
end
end
assign iready = ~unit_valid[LATENCY*O_W + O_W -1];
assign odata_s = idata_d_nx[O_W*UNIT_W-1:0];
assign ovalid_s = unit_valid[O_W-1];
generate
if (O_REG) begin : o_reg
always @(posedge clk) begin
if (reset) begin
ovalid <= 1'b0;
end else begin
ovalid <= ovalid_s;
end
end
always @(posedge clk) begin
odata <= odata_s;
end
end else begin
always @(*) begin
odata = odata_s;
ovalid = ovalid_s;
end
end
endgenerate
endmodule