//------------------------------------------------------------------------------
//
// mac16_generic.v
// -----------------------------------------------------------------------------
// Generic 16-bit multiplier and 47-bit accumulator.
//
// Authors: Pavel Shatov
//
// Copyright (c) 2016, NORDUnet A/S
//
// 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 the NORDUnet nor the names of its contributors may be
// used to endorse or promote products derived from this software without
// specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 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 mac16_generic
(
input clk, // clock
input clr, // clear accumulator (active-high)
input ce, // enable clock (active-high)
input [15: 0] a, // operand input
input [15: 0] b, // operand input
output [46: 0] s // sum output
);
//
// Multiplier
//
wire [31: 0] p = {{16{1'b0}}, a} * {{16{1'b0}}, b};
wire [46: 0] p_ext = {{15{1'b0}}, p};
//
// Accumulator
//
reg [46: 0] s_int;
always @(posedge clk)
//
if (ce) s_int <= clr ? p_ext : p_ext + s_int;
//
// Output
//
assign s = s_int;
endmodule
//------------------------------------------------------------------------------
// End-of-File
//------------------------------------------------------------------------------
