// ***************************************************************************
// ***************************************************************************
// Copyright 2013(c) Analog Devices, Inc.
//  Author: Lars-Peter Clausen <lars@metafoo.de>
// 
// 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 dmac_response_generator (
	input clk,
	input resetn,

	input enable,
	output reg enabled,

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

	input eot,

	output resp_valid,
	input resp_ready,
	output resp_eot,
	output [1:0] resp_resp
);

parameter C_ID_WIDTH = 3;

`include "inc_id.h"
`include "resp.h"

assign resp_resp = RESP_OKAY;
assign resp_eot = eot;

assign resp_valid = request_id != response_id;

// We have to wait for all responses before we can disable the response handler
always @(posedge clk) begin
	if (resetn == 1'b0) begin
		enabled <= 1'b0;
	end else begin
		if (enable)
			enabled <= 1'b1;
		else if (request_id == response_id)
			enabled <= 1'b0;
	end
end

always @(posedge clk) begin
	if (resetn == 1'b0) begin
		response_id <= 'h0;
	end else begin
		if ((resp_valid && resp_ready) ||
			(sync_id && response_id != request_id))
			response_id <= inc_id(response_id);
	end
end

endmodule