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Diffstat (limited to 'src/rtl/shr.v')
| -rw-r--r-- | src/rtl/shr.v | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/src/rtl/shr.v b/src/rtl/shr.v new file mode 100644 index 0000000..40ef111 --- /dev/null +++ b/src/rtl/shr.v @@ -0,0 +1,56 @@ +//====================================================================== +// +// shr32.v +// ------- +// One bit right shift with carry in and carry out. +// Used in the montprod module of the modexp core. +// +// +// Author: Peter Magnusson, Joachim Strömbergson +// Copyright (c) 2015, NORDUnet A/S 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 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 shr #(parameter OPW = 32) + ( + input wire [(OPW - 1) : 0] a, + input wire carry_in, + + output wire [(OPW - 1) : 0] adiv2, + output wire carry_out + ); + + assign adiv2 = {carry_in, a[(OPW - 1) : 1]}; + assign carry_out = a[0]; + +endmodule // shr + +//====================================================================== +// EOF shr.v +//====================================================================== |