1 /* 7zCrcOpt.c -- CRC32 calculation : optimized version 2 2009-11-23 : Igor Pavlov : Public domain */ 3 4 #include "CpuArch.h" 5 6 #ifdef MY_CPU_LE 7 8 #define CRC_UPDATE_BYTE_2(crc, b) (table[((crc) ^ (b)) & 0xFF] ^ ((crc) >> 8)) 9 10 UInt32 MY_FAST_CALL CrcUpdateT4(UInt32 v, const void *data, size_t size, const UInt32 *table) 11 { 12 const Byte *p = (const Byte *)data; 13 for (; size > 0 && ((unsigned)(ptrdiff_t)p & 3) != 0; size--, p++) 14 v = CRC_UPDATE_BYTE_2(v, *p); 15 for (; size >= 4; size -= 4, p += 4) 16 { 17 v ^= *(const UInt32 *)p; 18 v = 19 table[0x300 + (v & 0xFF)] ^ 20 table[0x200 + ((v >> 8) & 0xFF)] ^ 21 table[0x100 + ((v >> 16) & 0xFF)] ^ 22 table[0x000 + ((v >> 24))]; 23 } 24 for (; size > 0; size--, p++) 25 v = CRC_UPDATE_BYTE_2(v, *p); 26 return v; 27 } 28 29 UInt32 MY_FAST_CALL CrcUpdateT8(UInt32 v, const void *data, size_t size, const UInt32 *table) 30 { 31 return CrcUpdateT4(v, data, size, table); 32 } 33 34 #endif 35
