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https://gitlab.com/qemu-project/qemu
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ff7a1eb0a1
The new formulation makes better use of add-with-carry type insns that the host may have. Use gcc's sign adjustment trick to avoid having to perform a 128-bit negation. Signed-off-by: Richard Henderson <rth@twiddle.net> Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
89 lines
2.5 KiB
C
89 lines
2.5 KiB
C
/*
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* Utility compute operations used by translated code.
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*
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* Copyright (c) 2003 Fabrice Bellard
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* Copyright (c) 2007 Aurelien Jarno
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* 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, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include <stdlib.h>
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#include <stdint.h>
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#include "qemu/host-utils.h"
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/* Long integer helpers */
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#ifndef CONFIG_INT128
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static inline void mul64(uint64_t *plow, uint64_t *phigh,
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uint64_t a, uint64_t b)
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{
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typedef union {
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uint64_t ll;
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struct {
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#ifdef HOST_WORDS_BIGENDIAN
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uint32_t high, low;
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#else
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uint32_t low, high;
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#endif
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} l;
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} LL;
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LL rl, rm, rn, rh, a0, b0;
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uint64_t c;
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a0.ll = a;
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b0.ll = b;
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rl.ll = (uint64_t)a0.l.low * b0.l.low;
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rm.ll = (uint64_t)a0.l.low * b0.l.high;
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rn.ll = (uint64_t)a0.l.high * b0.l.low;
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rh.ll = (uint64_t)a0.l.high * b0.l.high;
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c = (uint64_t)rl.l.high + rm.l.low + rn.l.low;
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rl.l.high = c;
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c >>= 32;
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c = c + rm.l.high + rn.l.high + rh.l.low;
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rh.l.low = c;
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rh.l.high += (uint32_t)(c >> 32);
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*plow = rl.ll;
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*phigh = rh.ll;
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}
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/* Unsigned 64x64 -> 128 multiplication */
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void mulu64 (uint64_t *plow, uint64_t *phigh, uint64_t a, uint64_t b)
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{
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mul64(plow, phigh, a, b);
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}
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/* Signed 64x64 -> 128 multiplication */
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void muls64 (uint64_t *plow, uint64_t *phigh, int64_t a, int64_t b)
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{
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uint64_t rh;
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mul64(plow, &rh, a, b);
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/* Adjust for signs. */
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if (b < 0) {
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rh -= a;
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}
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if (a < 0) {
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rh -= b;
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}
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*phigh = rh;
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}
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#endif /* !CONFIG_INT128 */
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