diff options
Diffstat (limited to 'Utilities/cmliblzma/liblzma/check/crc64_small.c')
-rw-r--r-- | Utilities/cmliblzma/liblzma/check/crc64_small.c | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/Utilities/cmliblzma/liblzma/check/crc64_small.c b/Utilities/cmliblzma/liblzma/check/crc64_small.c new file mode 100644 index 000000000..55d72316b --- /dev/null +++ b/Utilities/cmliblzma/liblzma/check/crc64_small.c @@ -0,0 +1,53 @@ +/////////////////////////////////////////////////////////////////////////////// +// +/// \file crc64_small.c +/// \brief CRC64 calculation (size-optimized) +// +// Author: Lasse Collin +// +// This file has been put into the public domain. +// You can do whatever you want with this file. +// +/////////////////////////////////////////////////////////////////////////////// + +#include "check.h" + + +static uint64_t crc64_table[256]; + + +static void +crc64_init(void) +{ + static const uint64_t poly64 = UINT64_C(0xC96C5795D7870F42); + + for (size_t b = 0; b < 256; ++b) { + uint64_t r = b; + for (size_t i = 0; i < 8; ++i) { + if (r & 1) + r = (r >> 1) ^ poly64; + else + r >>= 1; + } + + crc64_table[b] = r; + } + + return; +} + + +extern LZMA_API(uint64_t) +lzma_crc64(const uint8_t *buf, size_t size, uint64_t crc) +{ + mythread_once(crc64_init); + + crc = ~crc; + + while (size != 0) { + crc = crc64_table[*buf++ ^ (crc & 0xFF)] ^ (crc >> 8); + --size; + } + + return ~crc; +} |