62 lines
1.8 KiB
C
62 lines
1.8 KiB
C
/*
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* Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#include "inner.h"
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/* see inner.h */
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void
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br_i31_mulacc(uint32_t *d, const uint32_t *a, const uint32_t *b)
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{
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size_t alen, blen, u;
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uint32_t dl, dh;
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alen = (a[0] + 31) >> 5;
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blen = (b[0] + 31) >> 5;
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/*
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* We want to add the two bit lengths, but these are encoded,
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* which requires some extra care.
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*/
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dl = (a[0] & 31) + (b[0] & 31);
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dh = (a[0] >> 5) + (b[0] >> 5);
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d[0] = (dh << 5) + dl + (~(uint32_t)(dl - 31) >> 31);
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for (u = 0; u < blen; u ++) {
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uint32_t f;
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size_t v;
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uint64_t cc;
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f = b[1 + u];
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cc = 0;
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for (v = 0; v < alen; v ++) {
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uint64_t z;
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z = (uint64_t)d[1 + u + v] + MUL31(f, a[1 + v]) + cc;
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cc = z >> 31;
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d[1 + u + v] = (uint32_t)z & 0x7FFFFFFF;
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}
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d[1 + u + alen] = (uint32_t)cc;
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}
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}
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