52 lines
1.6 KiB
C
52 lines
1.6 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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uint32_t
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br_i32_add(uint32_t *a, const uint32_t *b, uint32_t ctl)
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{
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uint32_t cc;
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size_t u, m;
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cc = 0;
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m = (a[0] + 63) >> 5;
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for (u = 1; u < m; u ++) {
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uint32_t aw, bw, naw;
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aw = a[u];
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bw = b[u];
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naw = aw + bw + cc;
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/*
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* Carry is 1 if naw < aw. Carry is also 1 if naw == aw
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* AND the carry was already 1.
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*/
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cc = (cc & EQ(naw, aw)) | LT(naw, aw);
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a[u] = MUX(ctl, naw, aw);
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}
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return cc;
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}
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