1/////////////////////////////////////////////////////////////////////////////// 2// 3/// \file crc64.c 4/// \brief CRC64 calculation 5/// 6/// Calculate the CRC64 using the slice-by-four algorithm. This is the same 7/// idea that is used in crc32_fast.c, but for CRC64 we use only four tables 8/// instead of eight to avoid increasing CPU cache usage. 9// 10// Author: Lasse Collin 11// 12// This file has been put into the public domain. 13// You can do whatever you want with this file. 14// 15/////////////////////////////////////////////////////////////////////////////// 16 17#include "check.h" 18#include "crc_macros.h" 19 20 21#ifdef WORDS_BIGENDIAN 22# define A1(x) ((x) >> 56) 23#else 24# define A1 A 25#endif 26 27 28// See the comments in crc32_fast.c. They aren't duplicated here. 29extern LZMA_API(uint64_t) 30lzma_crc64(const uint8_t *buf, size_t size, uint64_t crc) 31{ 32 crc = ~crc; 33 34#ifdef WORDS_BIGENDIAN 35 crc = bswap64(crc); 36#endif 37 38 if (size > 4) { 39 while ((uintptr_t)(buf) & 3) { 40 crc = lzma_crc64_table[0][*buf++ ^ A1(crc)] ^ S8(crc); 41 --size; 42 } 43 44 const uint8_t *const limit = buf + (size & ~(size_t)(3)); 45 size &= (size_t)(3); 46 47 while (buf < limit) { 48#ifdef WORDS_BIGENDIAN 49 const uint32_t tmp = (crc >> 32) 50 ^ *(const uint32_t *)(buf); 51#else 52 const uint32_t tmp = crc ^ *(const uint32_t *)(buf); 53#endif 54 buf += 4; 55 56 crc = lzma_crc64_table[3][A(tmp)] 57 ^ lzma_crc64_table[2][B(tmp)] 58 ^ S32(crc) 59 ^ lzma_crc64_table[1][C(tmp)] 60 ^ lzma_crc64_table[0][D(tmp)]; 61 } 62 } 63 64 while (size-- != 0) 65 crc = lzma_crc64_table[0][*buf++ ^ A1(crc)] ^ S8(crc); 66 67#ifdef WORDS_BIGENDIAN 68 crc = bswap64(crc); 69#endif 70 71 return ~crc; 72} 73