From dc25573ed79a0d55c5a24b20474aa8504a758a2c Mon Sep 17 00:00:00 2001 From: David Monniaux Date: Sat, 2 Feb 2019 12:03:44 +0100 Subject: BearSSL --- test/monniaux/BearSSL/src/int/i32_sub.c | 51 +++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) create mode 100644 test/monniaux/BearSSL/src/int/i32_sub.c (limited to 'test/monniaux/BearSSL/src/int/i32_sub.c') diff --git a/test/monniaux/BearSSL/src/int/i32_sub.c b/test/monniaux/BearSSL/src/int/i32_sub.c new file mode 100644 index 00000000..9c500238 --- /dev/null +++ b/test/monniaux/BearSSL/src/int/i32_sub.c @@ -0,0 +1,51 @@ +/* + * Copyright (c) 2016 Thomas Pornin + * + * Permission is hereby granted, free of charge, to any person obtaining + * a copy of this software and associated documentation files (the + * "Software"), to deal in the Software without restriction, including + * without limitation the rights to use, copy, modify, merge, publish, + * distribute, sublicense, and/or sell copies of the Software, and to + * permit persons to whom the Software is furnished to do so, subject to + * the following conditions: + * + * The above copyright notice and this permission notice shall be + * included in all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, + * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND + * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS + * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN + * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN + * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE + * SOFTWARE. + */ + +#include "inner.h" + +/* see inner.h */ +uint32_t +br_i32_sub(uint32_t *a, const uint32_t *b, uint32_t ctl) +{ + uint32_t cc; + size_t u, m; + + cc = 0; + m = (a[0] + 63) >> 5; + for (u = 1; u < m; u ++) { + uint32_t aw, bw, naw; + + aw = a[u]; + bw = b[u]; + naw = aw - bw - cc; + + /* + * Carry is 1 if naw > aw. Carry is 1 also if naw == aw + * AND the carry was already 1. + */ + cc = (cc & EQ(naw, aw)) | GT(naw, aw); + a[u] = MUX(ctl, naw, aw); + } + return cc; +} -- cgit