From a66be3237f5e9f4b6144cec093b047acfd70ffc6 Mon Sep 17 00:00:00 2001 From: "Pavel V. Shatov (Meister)" Date: Sun, 4 Dec 2016 23:07:58 +0300 Subject: Added README.md with core description, API details, etc Added previously forgotten generic replacements for vendor-specific primitives Minor clean up of comments Slightly reduced power consumption --- rtl/lowlevel/generic/subtractor32_generic.v | 67 +++++++++++++++++++++++++++++ 1 file changed, 67 insertions(+) create mode 100644 rtl/lowlevel/generic/subtractor32_generic.v (limited to 'rtl/lowlevel/generic/subtractor32_generic.v') diff --git a/rtl/lowlevel/generic/subtractor32_generic.v b/rtl/lowlevel/generic/subtractor32_generic.v new file mode 100644 index 0000000..46aefe8 --- /dev/null +++ b/rtl/lowlevel/generic/subtractor32_generic.v @@ -0,0 +1,67 @@ +//------------------------------------------------------------------------------ +// +// subtractor32_generic.v +// ----------------------------------------------------------------------------- +// Generic 32-bit subtractor. +// +// 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 subtractor32_generic + ( + input clk, + input [31: 0] a, + input [31: 0] b, + output [31: 0] d, + input b_in, + output b_out + ); + + // + // Difference + // + reg [32: 0] d_int; + + always @(posedge clk) + d_int <= {1'b0, a} - {1'b0, b} - {{32{1'b0}}, b_in}; + + // + // Output + // + assign d = d_int[31:0]; + assign b_out = d_int[32]; + +endmodule + +//------------------------------------------------------------------------------ +// End-of-File +//------------------------------------------------------------------------------ -- cgit v1.2.3