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/i31_mulacc.c | 74 ++++++++++++++++++++++++++++++ 1 file changed, 74 insertions(+) create mode 100644 test/monniaux/BearSSL/src/int/i31_mulacc.c (limited to 'test/monniaux/BearSSL/src/int/i31_mulacc.c') diff --git a/test/monniaux/BearSSL/src/int/i31_mulacc.c b/test/monniaux/BearSSL/src/int/i31_mulacc.c new file mode 100644 index 00000000..7410e546 --- /dev/null +++ b/test/monniaux/BearSSL/src/int/i31_mulacc.c @@ -0,0 +1,74 @@ +/* + * 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 */ +void +br_i31_mulacc(uint32_t *d, const uint32_t *a, const uint32_t *b) +{ + size_t alen, blen, u; + uint32_t dl, dh; + + alen = (a[0] + 31) >> 5; + blen = (b[0] + 31) >> 5; + + /* + * We want to add the two bit lengths, but these are encoded, + * which requires some extra care. + */ + dl = (a[0] & 31) + (b[0] & 31); + dh = (a[0] >> 5) + (b[0] >> 5); + d[0] = (dh << 5) + dl + (~(uint32_t)(dl - 31) >> 31); + + for (u = 0; u < blen; u ++) { + uint32_t f; + size_t v; + + /* + * Carry always fits on 31 bits; we want to keep it in a + * 32-bit register on 32-bit architectures (on a 64-bit + * architecture, cast down from 64 to 32 bits means + * clearing the high bits, which is not free; on a 32-bit + * architecture, the same operation really means ignoring + * the top register, which has negative or zero cost). + */ +#if BR_64 + uint64_t cc; +#else + uint32_t cc; +#endif + + f = b[1 + u]; + cc = 0; + for (v = 0; v < alen; v ++) { + uint64_t z; + + z = (uint64_t)d[1 + u + v] + MUL31(f, a[1 + v]) + cc; + cc = z >> 31; + d[1 + u + v] = (uint32_t)z & 0x7FFFFFFF; + } + d[1 + u + alen] = (uint32_t)cc; + } +} -- cgit