1 // SPDX-License-Identifier: 0BSD 2 3 /////////////////////////////////////////////////////////////////////////////// 4 // 5 /// \file crc64_small.c 6 /// \brief CRC64 calculation (size-optimized) 7 // 8 // Author: Lasse Collin 9 // 10 /////////////////////////////////////////////////////////////////////////////// 11 12 #include "check.h" 13 14 15 static uint64_t crc64_table[256]; 16 17 18 #ifdef HAVE_FUNC_ATTRIBUTE_CONSTRUCTOR 19 __attribute__((__constructor__)) 20 #endif 21 static void 22 crc64_init(void) 23 { 24 static const uint64_t poly64 = UINT64_C(0xC96C5795D7870F42); 25 26 for (size_t b = 0; b < 256; ++b) { 27 uint64_t r = b; 28 for (size_t i = 0; i < 8; ++i) { 29 if (r & 1) 30 r = (r >> 1) ^ poly64; 31 else 32 r >>= 1; 33 } 34 35 crc64_table[b] = r; 36 } 37 38 return; 39 } 40 41 42 extern LZMA_API(uint64_t) 43 lzma_crc64(const uint8_t *buf, size_t size, uint64_t crc) 44 { 45 #ifndef HAVE_FUNC_ATTRIBUTE_CONSTRUCTOR 46 mythread_once(crc64_init); 47 #endif 48 49 crc = ~crc; 50 51 while (size != 0) { 52 crc = crc64_table[*buf++ ^ (crc & 0xFF)] ^ (crc >> 8); 53 --size; 54 } 55 56 return ~crc; 57 } 58