mirror of
https://github.com/libretro/RetroArch
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140 lines
3.9 KiB
C
140 lines
3.9 KiB
C
/* Copyright (C) 2010-2016 The RetroArch team
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*
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* ---------------------------------------------------------------------------------------
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* The following license statement only applies to this file (mismatch.c).
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* ---------------------------------------------------------------------------------------
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*
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* Permission is hereby granted, free of charge,
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* to any person obtaining a copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation the rights to
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* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software,
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* and to permit persons to whom the Software is 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 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 IMPLIED,
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* INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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* 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 THE SOFTWARE.
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*/
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#include <stdint.h>
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#include <stdlib.h>
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#include <string.h>
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#include <retro_inline.h>
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#include <algorithms/mismatch.h>
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#include <compat/intrinsics.h>
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#if defined(__x86_64__) || defined(__i386__) || defined(__i486__) || defined(__i686__)
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#define CPU_X86
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#endif
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/* Other arches SIGBUS (usually) on unaligned accesses. */
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#ifndef CPU_X86
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#define NO_UNALIGNED_MEM
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#endif
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#if __SSE2__
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#include <emmintrin.h>
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#endif
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/* There's no equivalent in libc, you'd think so ...
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* std::mismatch exists, but it's not optimized at all. */
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size_t find_change(const uint16_t *a, const uint16_t *b)
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{
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#if __SSE2__
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const __m128i *a128 = (const __m128i*)a;
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const __m128i *b128 = (const __m128i*)b;
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for (;;)
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{
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__m128i v0 = _mm_loadu_si128(a128);
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__m128i v1 = _mm_loadu_si128(b128);
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__m128i c = _mm_cmpeq_epi32(v0, v1);
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uint32_t mask = _mm_movemask_epi8(c);
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if (mask != 0xffff) /* Something has changed, figure out where. */
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{
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size_t ret = (((uint8_t*)a128 - (uint8_t*)a) |
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(compat_ctz(~mask))) >> 1;
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return ret | (a[ret] == b[ret]);
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}
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a128++;
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b128++;
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}
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#else
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const uint16_t *a_org = a;
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#ifdef NO_UNALIGNED_MEM
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while (((uintptr_t)a & (sizeof(size_t) - 1)) && *a == *b)
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{
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a++;
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b++;
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}
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if (*a == *b)
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#endif
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{
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const size_t *a_big = (const size_t*)a;
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const size_t *b_big = (const size_t*)b;
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while (*a_big == *b_big)
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{
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a_big++;
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b_big++;
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}
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a = (const uint16_t*)a_big;
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b = (const uint16_t*)b_big;
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while (*a == *b)
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{
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a++;
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b++;
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}
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}
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return a - a_org;
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#endif
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}
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size_t find_same(const uint16_t *a, const uint16_t *b)
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{
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const uint16_t *a_org = a;
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#ifdef NO_UNALIGNED_MEM
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if (((uintptr_t)a & (sizeof(uint32_t) - 1)) && *a != *b)
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{
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a++;
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b++;
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}
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if (*a != *b)
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#endif
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{
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/* With this, it's random whether two consecutive identical
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* words are caught.
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*
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* Luckily, compression rate is the same for both cases, and
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* three is always caught.
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*
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* (We prefer to miss two-word blocks, anyways; fewer iterations
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* of the outer loop, as well as in the decompressor.) */
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const uint32_t *a_big = (const uint32_t*)a;
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const uint32_t *b_big = (const uint32_t*)b;
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while (*a_big != *b_big)
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{
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a_big++;
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b_big++;
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}
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a = (const uint16_t*)a_big;
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b = (const uint16_t*)b_big;
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if (a != a_org && a[-1] == b[-1])
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{
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a--;
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b--;
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}
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}
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return a - a_org;
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}
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