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//
// Copyright 2011 Ettus Research LLC
// Copyright 2018 Ettus Research, a National Instruments Company
//
// SPDX-License-Identifier: LGPL-3.0-or-later
//
module acc
#(parameter IWIDTH=16, OWIDTH=30)
(input clk,
input clear,
input acc,
input [IWIDTH-1:0] in,
output reg [OWIDTH-1:0] out);
wire [OWIDTH-1:0] in_signext;
sign_extend #(.bits_in(IWIDTH),.bits_out(OWIDTH))
acc_signext (.in(in),.out(in_signext));
// CLEAR & ~ACC --> clears the accumulator
// CLEAR & ACC --> loads the accumulator
// ~CLEAR & ACC --> accumulates
// ~CLEAR & ~ACC --> hold
wire [OWIDTH-1:0] addend1 = clear ? 0 : out;
wire [OWIDTH-1:0] addend2 = ~acc ? 0 : in_signext;
wire [OWIDTH-1:0] sum_int = addend1 + addend2;
always @(posedge clk)
out <= sum_int;
endmodule // acc
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