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//
// Copyright 2012 Ettus Research, a National Instruments Company
//
// SPDX-License-Identifier: LGPL-3.0-or-later
//
//
// axi_loopback.v
//
// Loopback all data assuming it's in CHDR format, and swap SRC/DST in the SID in the process
// thus reflecting it back to it's origin...in theory!
//
module axi_loopback
#(
parameter WIDTH = 64
)
(
input clk,
input reset,
// Input AXIS
input [WIDTH-1:0] i_tdata,
input i_tlast,
input i_tvalid,
output i_tready,
// Output AXIS
output [WIDTH-1:0] o_tdata,
output o_tlast,
output o_tvalid,
input o_tready
);
wire [WIDTH-1:0] fifoin_tdata,fifoout_tdata,dmux_tdata;
wire fifoin_tlast,dmux_tlast;
wire fifoin_tvalid,dmux_tvalid;
wire fifoin_tready,dmux_tready;
// Since most real endpoints go via Demux4 place one in here to look for bugs.
axi_demux4 #(.ACTIVE_CHAN(4'b0001), .WIDTH(WIDTH)) demux
(.clk(clk), .reset(reset), .clear(1'b0),
.header(), .dest(2'b00),
.i_tdata(i_tdata), .i_tlast(i_tlast), .i_tvalid(i_tvalid), .i_tready(i_tready),
.o0_tdata(dmux_tdata), .o0_tlast(dmux_tlast), .o0_tvalid(dmux_tvalid), .o0_tready(dmux_tready),
.o1_tdata(), .o1_tlast(), .o1_tvalid(), .o1_tready(1'b1),
.o2_tdata(), .o2_tlast(), .o2_tvalid(), .o2_tready(1'b1),
.o3_tdata(), .o3_tlast(), .o3_tvalid(), .o3_tready(1'b1));
axi_fifo_short #(.WIDTH(WIDTH+1)) axi_fifo_short1
(.clk(clk), .reset(reset), .clear(1'b0),
.i_tdata({dmux_tlast,dmux_tdata}), .i_tvalid(dmux_tvalid), .i_tready(dmux_tready),
.o_tdata({fifoin_tlast,fifoin_tdata}), .o_tvalid(fifoin_tvalid), .o_tready(fifoin_tready),
.space(), .occupied());
reg header;
always @(posedge clk) begin
if(reset) begin
header <= 1'b1;
end else if (header) begin
if(fifoin_tvalid & fifoin_tready & ~fifoin_tlast) header <= 1'b0;
end else begin
if(fifoin_tvalid & fifoin_tready & fifoin_tlast) header <= 1'b1;
end
end
assign fifoout_tdata = header ?
{fifoin_tdata[63:32] ,fifoin_tdata[15:0],fifoin_tdata[31:16]} :
fifoin_tdata;
axi_fifo_short #(.WIDTH(WIDTH+1)) axi_fifo_short2
(.clk(clk), .reset(reset), .clear(1'b0),
.i_tdata({fifoin_tlast,fifoout_tdata}), .i_tvalid(fifoin_tvalid), .i_tready(fifoin_tready),
.o_tdata({o_tlast,o_tdata}), .o_tvalid(o_tvalid), .o_tready(o_tready),
.space(), .occupied());
endmodule // axi_loopback
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