diff options
Diffstat (limited to 'Utilities/cmliblzma/liblzma/check/crc64_fast.c')
-rw-r--r-- | Utilities/cmliblzma/liblzma/check/crc64_fast.c | 72 |
1 files changed, 72 insertions, 0 deletions
diff --git a/Utilities/cmliblzma/liblzma/check/crc64_fast.c b/Utilities/cmliblzma/liblzma/check/crc64_fast.c new file mode 100644 index 0000000..52af29e --- /dev/null +++ b/Utilities/cmliblzma/liblzma/check/crc64_fast.c @@ -0,0 +1,72 @@ +/////////////////////////////////////////////////////////////////////////////// +// +/// \file crc64.c +/// \brief CRC64 calculation +/// +/// Calculate the CRC64 using the slice-by-four algorithm. This is the same +/// idea that is used in crc32_fast.c, but for CRC64 we use only four tables +/// instead of eight to avoid increasing CPU cache usage. +// +// Author: Lasse Collin +// +// This file has been put into the public domain. +// You can do whatever you want with this file. +// +/////////////////////////////////////////////////////////////////////////////// + +#include "check.h" +#include "crc_macros.h" + + +#ifdef WORDS_BIGENDIAN +# define A1(x) ((x) >> 56) +#else +# define A1 A +#endif + + +// See the comments in crc32_fast.c. They aren't duplicated here. +extern LZMA_API(uint64_t) +lzma_crc64(const uint8_t *buf, size_t size, uint64_t crc) +{ + crc = ~crc; + +#ifdef WORDS_BIGENDIAN + crc = bswap64(crc); +#endif + + if (size > 4) { + while ((uintptr_t)(buf) & 3) { + crc = lzma_crc64_table[0][*buf++ ^ A1(crc)] ^ S8(crc); + --size; + } + + const uint8_t *const limit = buf + (size & ~(size_t)(3)); + size &= (size_t)(3); + + while (buf < limit) { +#ifdef WORDS_BIGENDIAN + const uint32_t tmp = (crc >> 32) + ^ *(const uint32_t *)(buf); +#else + const uint32_t tmp = crc ^ *(const uint32_t *)(buf); +#endif + buf += 4; + + crc = lzma_crc64_table[3][A(tmp)] + ^ lzma_crc64_table[2][B(tmp)] + ^ S32(crc) + ^ lzma_crc64_table[1][C(tmp)] + ^ lzma_crc64_table[0][D(tmp)]; + } + } + + while (size-- != 0) + crc = lzma_crc64_table[0][*buf++ ^ A1(crc)] ^ S8(crc); + +#ifdef WORDS_BIGENDIAN + crc = bswap64(crc); +#endif + + return ~crc; +} |