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/* Copyright (C) 2010-2016 The RetroArch team
*
* ---------------------------------------------------------------------------------------
* The following license statement only applies to this file (mismatch.c).
* ---------------------------------------------------------------------------------------
*
* 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 <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <retro_inline.h>
#include <algorithms/mismatch.h>
#include <compat/intrinsics.h>
#if defined(__x86_64__) || defined(__i386__) || defined(__i486__) || defined(__i686__)
#define CPU_X86
#endif
/* Other arches SIGBUS (usually) on unaligned accesses. */
#ifndef CPU_X86
#define NO_UNALIGNED_MEM
#endif
#if __SSE2__
#include <emmintrin.h>
#endif
/* There's no equivalent in libc, you'd think so ...
* std::mismatch exists, but it's not optimized at all. */
size_t find_change(const uint16_t *a, const uint16_t *b)
{
#if __SSE2__
const __m128i *a128 = (const __m128i*)a;
const __m128i *b128 = (const __m128i*)b;
for (;;)
{
__m128i v0 = _mm_loadu_si128(a128);
__m128i v1 = _mm_loadu_si128(b128);
__m128i c = _mm_cmpeq_epi32(v0, v1);
uint32_t mask = _mm_movemask_epi8(c);
if (mask != 0xffff) /* Something has changed, figure out where. */
{
size_t ret = (((uint8_t*)a128 - (uint8_t*)a) |
(compat_ctz(~mask))) >> 1;
return ret | (a[ret] == b[ret]);
}
a128++;
b128++;
}
#else
const uint16_t *a_org = a;
#ifdef NO_UNALIGNED_MEM
while (((uintptr_t)a & (sizeof(size_t) - 1)) && *a == *b)
{
a++;
b++;
}
if (*a == *b)
#endif
{
const size_t *a_big = (const size_t*)a;
const size_t *b_big = (const size_t*)b;
while (*a_big == *b_big)
{
a_big++;
b_big++;
}
a = (const uint16_t*)a_big;
b = (const uint16_t*)b_big;
while (*a == *b)
{
a++;
b++;
}
}
return a - a_org;
#endif
}
size_t find_same(const uint16_t *a, const uint16_t *b)
{
const uint16_t *a_org = a;
#ifdef NO_UNALIGNED_MEM
if (((uintptr_t)a & (sizeof(uint32_t) - 1)) && *a != *b)
{
a++;
b++;
}
if (*a != *b)
#endif
{
/* With this, it's random whether two consecutive identical
* words are caught.
*
* Luckily, compression rate is the same for both cases, and
* three is always caught.
*
* (We prefer to miss two-word blocks, anyways; fewer iterations
* of the outer loop, as well as in the decompressor.) */
const uint32_t *a_big = (const uint32_t*)a;
const uint32_t *b_big = (const uint32_t*)b;
while (*a_big != *b_big)
{
a_big++;
b_big++;
}
a = (const uint16_t*)a_big;
b = (const uint16_t*)b_big;
if (a != a_org && a[-1] == b[-1])
{
a--;
b--;
}
}
return a - a_org;
}
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