diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/liblzma/common/memcmplen.h | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/src/liblzma/common/memcmplen.h b/src/liblzma/common/memcmplen.h index f66e7cdb..c1efc9e2 100644 --- a/src/liblzma/common/memcmplen.h +++ b/src/liblzma/common/memcmplen.h @@ -19,11 +19,6 @@ # include <immintrin.h> #endif -/// How many extra bytes lzma_memcmplen() may read. This depends on -/// the method but since it is just a few bytes the biggest possible -/// value is used here. -#define LZMA_MEMCMPLEN_EXTRA 16 - /// Find out how many equal bytes the two buffers have. /// @@ -39,6 +34,11 @@ /// /// \return Number of equal bytes in the buffers is returned. /// This is always at least len and at most limit. +/// +/// \note LZMA_MEMCMPLEN_EXTRA defines how many extra bytes may be read. +/// It's rounded up to 2^n. This extra amount needs to be +/// allocated in the buffers being used. It needs to be +/// initialized too to keep Valgrind quiet. static inline uint32_t lzma_attribute((__always_inline__)) lzma_memcmplen(const uint8_t *buf1, const uint8_t *buf2, uint32_t len, uint32_t limit) @@ -59,6 +59,7 @@ lzma_memcmplen(const uint8_t *buf1, const uint8_t *buf2, // to be a good method. This may be fine on other 64-bit CPUs too. // On big endian one should use xor instead of subtraction and switch // to __builtin_clzll(). +#define LZMA_MEMCMPLEN_EXTRA 8 while (len < limit) { const uint64_t x = *(const uint64_t *)(buf1 + len) - *(const uint64_t *)(buf2 + len); @@ -91,6 +92,7 @@ lzma_memcmplen(const uint8_t *buf1, const uint8_t *buf2, // version is sometimes significantly faster and sometimes // slightly slower than this SSE2 version, so this SSE2 // version isn't used on x86-64. +# define LZMA_MEMCMPLEN_EXTRA 16 while (len < limit) { const uint32_t x = 0xFFFF ^ _mm_movemask_epi8(_mm_cmpeq_epi8( _mm_loadu_si128((const __m128i *)(buf1 + len)), @@ -116,6 +118,7 @@ lzma_memcmplen(const uint8_t *buf1, const uint8_t *buf2, #elif defined(TUKLIB_FAST_UNALIGNED_ACCESS) && !defined(WORDS_BIGENDIAN) // Generic 32-bit little endian method +# define LZMA_MEMCMPLEN_EXTRA 4 while (len < limit) { uint32_t x = *(const uint32_t *)(buf1 + len) - *(const uint32_t *)(buf2 + len); @@ -138,6 +141,7 @@ lzma_memcmplen(const uint8_t *buf1, const uint8_t *buf2, #elif defined(TUKLIB_FAST_UNALIGNED_ACCESS) && defined(WORDS_BIGENDIAN) // Generic 32-bit big endian method +# define LZMA_MEMCMPLEN_EXTRA 4 while (len < limit) { uint32_t x = *(const uint32_t *)(buf1 + len) ^ *(const uint32_t *)(buf2 + len); @@ -160,6 +164,7 @@ lzma_memcmplen(const uint8_t *buf1, const uint8_t *buf2, #else // Simple portable version that doesn't use unaligned access. +# define LZMA_MEMCMPLEN_EXTRA 0 while (len < limit && buf1[len] == buf2[len]) ++len; |