pluto_hdl_adi/library/axi_dmac/request_generator.v

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// Copyright 2013(c) Analog Devices, Inc.
//  Author: Lars-Peter Clausen <lars@metafoo.de>
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module dmac_request_generator (
	input req_aclk,
	input req_aresetn,

	output [C_ID_WIDTH-1:0] request_id,
	input [C_ID_WIDTH-1:0] response_id,

	input req_valid,
	output reg req_ready,
	input [C_BURSTS_PER_TRANSFER_WIDTH-1:0] req_burst_count,

	input enable,
	input pause,

	output eot
);

parameter C_ID_WIDTH = 3;
parameter C_BURSTS_PER_TRANSFER_WIDTH = 17;

`include "inc_id.h"

/*
 * Here we only need to count the number of bursts, which means we can ignore
 * the lower bits of the byte count. The last last burst may not contain the
 * maximum number of bytes, but the address_generator and data_mover will take
 * care that only the requested ammount of bytes is transfered.
 */

reg [C_BURSTS_PER_TRANSFER_WIDTH-1:0] burst_count = 'h00;
reg [C_ID_WIDTH-1:0] id;
wire [C_ID_WIDTH-1:0] id_next = inc_id(id);

assign eot = burst_count == 'h00;
assign request_id = id;

always @(posedge req_aclk)
begin
	if (req_aresetn == 1'b0) begin
		burst_count <= 'h00;
		id <= 'h0;
		req_ready <= 1'b1;
	end else begin
		if (req_ready) begin
			if (req_valid && enable) begin
				burst_count <= req_burst_count;
				req_ready <= 1'b0;
			end
		end else if (response_id != id_next && ~pause) begin
			if (eot)
				req_ready <= 1'b1;
			burst_count <= burst_count - 1'b1;
			id <= id_next;
		end
	end
end

endmodule