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// ***************************************************************************
// ***************************************************************************
// Copyright 2013(c) Analog Devices, Inc.
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification,
// are permitted provided that the following conditions are met:
// - Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// - Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in
// the documentation and/or other materials provided with the
// distribution.
// - Neither the name of Analog Devices, Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
// - The use of this software may or may not infringe the patent rights
// of one or more patent holders. This license does not release you
// from the requirement that you obtain separate licenses from these
// patent holders to use this software.
// - Use of the software either in source or binary form, must be run
// on or directly connected to an Analog Devices Inc. component.
//
// THIS SOFTWARE IS PROVIDED BY ANALOG DEVICES "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
// INCLUDING, BUT NOT LIMITED TO, NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS FOR A
// PARTICULAR PURPOSE ARE DISCLAIMED.
//
// IN NO EVENT SHALL ANALOG DEVICES BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, INTELLECTUAL PROPERTY
// RIGHTS, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
// BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// ***************************************************************************
// ***************************************************************************
module axi_register_slice (
input clk,
input resetn,
input s_axi_valid,
output s_axi_ready,
input [DATA_WIDTH-1:0] s_axi_data,
output m_axi_valid,
input m_axi_ready,
output [DATA_WIDTH-1:0] m_axi_data
);
parameter DATA_WIDTH = 32;
parameter FORWARD_REGISTERED = 0;
parameter BACKWARD_REGISTERED = 0;
/*
s_axi_data -> bwd_data -> fwd_data(1) -> m_axi_data
s_axi_valid -> bwd_valid -> fwd_valid(1) -> m_axi_valid
s_axi_ready <- bwd_ready(2) <- fwd_ready <- m_axi_ready
(1) FORWARD_REGISTERED inserts a set of FF before m_axi_data and m_axi_valid
(2) BACKWARD_REGISTERED insters a FF before s_axi_ready
*/
wire [DATA_WIDTH-1:0] bwd_data_s;
wire bwd_valid_s;
wire bwd_ready_s;
wire [DATA_WIDTH-1:0] fwd_data_s;
wire fwd_valid_s;
wire fwd_ready_s;
generate if (FORWARD_REGISTERED == 1) begin
reg fwd_valid = 1'b0;
reg [DATA_WIDTH-1:0] fwd_data = 'h00;
assign fwd_ready_s = ~fwd_valid | m_axi_ready;
assign fwd_valid_s = fwd_valid;
assign fwd_data_s = fwd_data;
always @(posedge clk) begin
if (~fwd_valid | m_axi_ready)
fwd_data <= bwd_data_s;
end
always @(posedge clk) begin
if (resetn == 1'b0) begin
fwd_valid <= 1'b0;
end else begin
if (bwd_valid_s)
fwd_valid <= 1'b1;
else if (m_axi_ready)
fwd_valid <= 1'b0;
end
end
end else begin
assign fwd_data_s = bwd_data_s;
assign fwd_valid_s = bwd_valid_s;
assign fwd_ready_s = m_axi_ready;
end
endgenerate
generate if (BACKWARD_REGISTERED == 1) begin
reg bwd_ready = 1'b1;
reg [DATA_WIDTH-1:0] bwd_data = 'h00;
assign bwd_valid_s = ~bwd_ready | s_axi_valid;
assign bwd_data_s = bwd_ready ? s_axi_data : bwd_data;
assign bwd_ready_s = bwd_ready;
always @(posedge clk) begin
if (bwd_ready)
bwd_data <= s_axi_data;
end
always @(posedge clk) begin
if (resetn == 1'b0) begin
bwd_ready <= 1'b1;
end else begin
if (fwd_ready_s)
bwd_ready <= 1'b1;
else if (s_axi_valid)
bwd_ready <= 1'b0;
end
end
end else begin
assign bwd_valid_s = s_axi_valid;
assign bwd_data_s = s_axi_data;
assign bwd_ready_s = fwd_ready_s;
end endgenerate
assign m_axi_data = fwd_data_s;
assign m_axi_valid = fwd_valid_s;
assign s_axi_ready = bwd_ready_s;
endmodule
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