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Diffstat (limited to 'port/port_posix_sse.cc')
-rw-r--r-- | port/port_posix_sse.cc | 133 |
1 files changed, 0 insertions, 133 deletions
diff --git a/port/port_posix_sse.cc b/port/port_posix_sse.cc deleted file mode 100644 index 08d9aee..0000000 --- a/port/port_posix_sse.cc +++ /dev/null @@ -1,133 +0,0 @@ -// Copyright 2016 The LevelDB Authors. All rights reserved. -// Use of this source code is governed by a BSD-style license that can be -// found in the LICENSE file. See the AUTHORS file for names of contributors. -// -// A portable implementation of crc32c, optimized to handle -// four bytes at a time. -// -// In a separate source file to allow this accelerated CRC32C function to be -// compiled with the appropriate compiler flags to enable x86 SSE 4.2 -// instructions. - -#include <stdint.h> -#include <string.h> -#include "port/port.h" - -#if defined(LEVELDB_PLATFORM_POSIX_SSE) - -#if defined(_MSC_VER) -#include <intrin.h> -#elif defined(__GNUC__) && defined(__SSE4_2__) -#include <nmmintrin.h> -#include <cpuid.h> -#endif - -#endif // defined(LEVELDB_PLATFORM_POSIX_SSE) - -namespace leveldb { -namespace port { - -#if defined(LEVELDB_PLATFORM_POSIX_SSE) - -// Used to fetch a naturally-aligned 32-bit word in little endian byte-order -static inline uint32_t LE_LOAD32(const uint8_t *p) { - // SSE is x86 only, so ensured that |p| is always little-endian. - uint32_t word; - memcpy(&word, p, sizeof(word)); - return word; -} - -#if defined(_M_X64) || defined(__x86_64__) // LE_LOAD64 is only used on x64. - -// Used to fetch a naturally-aligned 64-bit word in little endian byte-order -static inline uint64_t LE_LOAD64(const uint8_t *p) { - uint64_t dword; - memcpy(&dword, p, sizeof(dword)); - return dword; -} - -#endif // defined(_M_X64) || defined(__x86_64__) - -static inline bool HaveSSE42() { -#if defined(_MSC_VER) - int cpu_info[4]; - __cpuid(cpu_info, 1); - return (cpu_info[2] & (1 << 20)) != 0; -#elif defined(__GNUC__) - unsigned int eax, ebx, ecx, edx; - __get_cpuid(1, &eax, &ebx, &ecx, &edx); - return (ecx & (1 << 20)) != 0; -#else - return false; -#endif -} - -#endif // defined(LEVELDB_PLATFORM_POSIX_SSE) - -// For further improvements see Intel publication at: -// http://download.intel.com/design/intarch/papers/323405.pdf -uint32_t AcceleratedCRC32C(uint32_t crc, const char* buf, size_t size) { -#if !defined(LEVELDB_PLATFORM_POSIX_SSE) - return 0; -#else - static bool have = HaveSSE42(); - if (!have) { - return 0; - } - - const uint8_t *p = reinterpret_cast<const uint8_t *>(buf); - const uint8_t *e = p + size; - uint32_t l = crc ^ 0xffffffffu; - -#define STEP1 do { \ - l = _mm_crc32_u8(l, *p++); \ -} while (0) -#define STEP4 do { \ - l = _mm_crc32_u32(l, LE_LOAD32(p)); \ - p += 4; \ -} while (0) -#define STEP8 do { \ - l = _mm_crc32_u64(l, LE_LOAD64(p)); \ - p += 8; \ -} while (0) - - if (size > 16) { - // Point x at first 8-byte aligned byte in string. This must be inside the - // string, due to the size check above. - const uintptr_t pval = reinterpret_cast<uintptr_t>(p); - const uint8_t* x = reinterpret_cast<const uint8_t*>(((pval + 7) >> 3) << 3); - // Process bytes until p is 8-byte aligned. - while (p != x) { - STEP1; - } - - // _mm_crc32_u64 is only available on x64. -#if defined(_M_X64) || defined(__x86_64__) - // Process 8 bytes at a time - while ((e-p) >= 8) { - STEP8; - } - // Process 4 bytes at a time - if ((e-p) >= 4) { - STEP4; - } -#else // !(defined(_M_X64) || defined(__x86_64__)) - // Process 4 bytes at a time - while ((e-p) >= 4) { - STEP4; - } -#endif // defined(_M_X64) || defined(__x86_64__) - } - // Process the last few bytes - while (p != e) { - STEP1; - } -#undef STEP8 -#undef STEP4 -#undef STEP1 - return l ^ 0xffffffffu; -#endif // defined(LEVELDB_PLATFORM_POSIX_SSE) -} - -} // namespace port -} // namespace leveldb |