118 lines
3.5 KiB
Verilog
118 lines
3.5 KiB
Verilog
// ***************************************************************************
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// ***************************************************************************
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// Copyright 2014 - 2017 (c) Analog Devices, Inc. All rights reserved.
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//
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// In this HDL repository, there are many different and unique modules, consisting
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// of various HDL (Verilog or VHDL) components. The individual modules are
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// developed independently, and may be accompanied by separate and unique license
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// terms.
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//
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// The user should read each of these license terms, and understand the
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// freedoms and responsabilities that he or she has by using this source/core.
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//
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// This core is distributed in the hope that it will be useful, but WITHOUT ANY
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// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
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// A PARTICULAR PURPOSE.
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//
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// Redistribution and use of source or resulting binaries, with or without modification
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// of this file, are permitted under one of the following two license terms:
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//
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// 1. The GNU General Public License version 2 as published by the
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// Free Software Foundation, which can be found in the top level directory
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// of this repository (LICENSE_GPL2), and also online at:
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// <https://www.gnu.org/licenses/old-licenses/gpl-2.0.html>
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//
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// OR
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//
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// 2. An ADI specific BSD license, which can be found in the top level directory
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// of this repository (LICENSE_ADIBSD), and also on-line at:
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// https://github.com/analogdevicesinc/hdl/blob/master/LICENSE_ADIBSD
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// This will allow to generate bit files and not release the source code,
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// as long as it attaches to an ADI device.
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//
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// ***************************************************************************
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// ***************************************************************************
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// A simple adder/substracter width preconfigured input ports width and turn-around value
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// Output = A - B_constant or A + B_constant
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// Constraints: Awidth >= Bwidth
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`timescale 1ns/1ps
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module ad_addsub #(
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parameter A_DATA_WIDTH = 32,
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parameter B_DATA_VALUE = 32'h1,
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parameter ADD_OR_SUB_N = 0) (
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input clk,
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input [(A_DATA_WIDTH-1):0] A,
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input [(A_DATA_WIDTH-1):0] Amax,
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output reg [(A_DATA_WIDTH-1):0] out,
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input CE);
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localparam ADDER = 1;
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localparam SUBSTRACTER = 0;
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// registers
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reg [A_DATA_WIDTH:0] out_d = 'b0;
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reg [A_DATA_WIDTH:0] out_d2 = 'b0;
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reg [(A_DATA_WIDTH-1):0] A_d = 'b0;
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reg [(A_DATA_WIDTH-1):0] A_d2 = 'b0;
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reg [(A_DATA_WIDTH-1):0] Amax_d = 'b0;
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reg [(A_DATA_WIDTH-1):0] Amax_d2 = 'b0;
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// constant regs
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reg [(A_DATA_WIDTH-1):0] B_reg = B_DATA_VALUE;
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// latch the inputs
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always @(posedge clk) begin
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A_d <= A;
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A_d2 <= A_d;
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Amax_d <= Amax;
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Amax_d2 <= Amax_d;
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end
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// ADDER/SUBSTRACTER
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always @(posedge clk) begin
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if ( ADD_OR_SUB_N == ADDER ) begin
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out_d <= A_d + B_reg;
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end else begin
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out_d <= A_d - B_reg;
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end
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end
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// Resolve
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always @(posedge clk) begin
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if ( ADD_OR_SUB_N == ADDER ) begin
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if ( out_d > Amax_d2 ) begin
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out_d2 <= out_d - Amax_d2;
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end else begin
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out_d2 <= out_d;
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end
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end else begin // SUBSTRACTER
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if ( out_d[A_DATA_WIDTH] == 1'b1 ) begin
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out_d2 <= Amax_d2 + out_d;
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end else begin
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out_d2 <= out_d;
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end
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end
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end
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// output logic
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always @(posedge clk) begin
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if ( CE ) begin
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out <= out_d2;
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end else begin
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out <= 'b0;
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end
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end
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endmodule
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