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//
// Copyright 2016 Ettus Research
// Copyright 2018 Ettus Research, a National Instruments Company
//
// SPDX-License-Identifier: LGPL-3.0-or-later
//
// Settings register with AXI stream output.
//
// Parameters / common use cases:
// USE_ADDR_LAST & ADDR_LAST User wants additional address that when written to asserts tlast.
// Useful for the last word in a packet.
// USE_FIFO & FIFO_SIZE Downstream block can throttle and a FIFO is needed to handle that case.
// STROBE_LAST User always wants to assert tlast on writes. More efficient than USE_ADDR_LAST
// since only one address is used instead of two.
// REPEATS Keep tvalid asserted after initial write.
// STROBE_LAST & REPEATS tlast is asserted on the initial write then deasserted for repeating output.
// MSB_ALIGN Left justify data versus right justify.
module axi_setting_reg #(
parameter ADDR = 0,
parameter USE_ADDR_LAST = 0,
parameter ADDR_LAST = ADDR+1,
parameter AWIDTH = 8,
parameter WIDTH = 32,
parameter USE_FIFO = 0,
parameter FIFO_SIZE = 5,
parameter DATA_AT_RESET = 0,
parameter VALID_AT_RESET = 0,
parameter LAST_AT_RESET = 0,
parameter STROBE_LAST = 0,
parameter REPEATS = 0,
parameter MSB_ALIGN = 0
)
(
input clk, input reset, output reg error_stb,
input set_stb, input [AWIDTH-1:0] set_addr, input [31:0] set_data,
output [WIDTH-1:0] o_tdata, output o_tlast, output o_tvalid, input o_tready
);
reg init;
reg [WIDTH-1:0] o_tdata_int;
reg o_tlast_int, o_tvalid_int = VALID_AT_RESET;
wire o_tready_int;
always @(posedge clk) begin
if (reset) begin
o_tdata_int <= DATA_AT_RESET;
o_tvalid_int <= VALID_AT_RESET;
o_tlast_int <= LAST_AT_RESET;
init <= 1'b0;
error_stb <= 1'b0;
end else begin
error_stb <= 1'b0;
if (o_tvalid_int & o_tready_int) begin
// Deassert tvalid / tlast only if not repeating the output
if (REPEATS == 0) begin
o_tvalid_int <= 1'b0;
end
if ((REPEATS == 0) | (STROBE_LAST == 1)) begin
o_tlast_int <= 1'b0;
end
end
if (set_stb & ((ADDR[AWIDTH-1:0] == set_addr) | (USE_ADDR_LAST & (ADDR_LAST[AWIDTH-1:0] == set_addr)))) begin
init <= 1'b1;
o_tdata_int <= (MSB_ALIGN == 0) ? set_data[WIDTH-1:0] : set_data[31:32-WIDTH];
o_tvalid_int <= 1'b1;
if (set_stb & (STROBE_LAST | (USE_ADDR_LAST & (ADDR_LAST[AWIDTH-1:0] == set_addr)))) begin
o_tlast_int <= 1'b1;
end else begin
o_tlast_int <= 1'b0;
end
if (~o_tready_int) begin
error_stb <= 1'b1;
end
end
end
end
generate
if (USE_FIFO) begin
axi_fifo #(
.WIDTH(WIDTH+1), .SIZE(FIFO_SIZE))
axi_fifo (
.clk(clk), .reset(reset), .clear(1'b0),
.i_tdata({o_tlast_int,o_tdata_int}), .i_tvalid(o_tvalid_int), .i_tready(o_tready_int),
.o_tdata({o_tlast,o_tdata}), .o_tvalid(o_tvalid), .o_tready(o_tready),
.space(), .occupied());
end else begin
assign o_tdata = o_tdata_int;
assign o_tlast = o_tlast_int;
assign o_tvalid = o_tvalid_int;
assign o_tready_int = o_tready;
end
endgenerate
endmodule
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