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| 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 U
Int32 *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 U
Int32 *table) |
| 30 { |
| 31 return CrcUpdateT4(v, data, size, table); |
| 32 } |
| 33 |
| 34 #endif |
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