35 lines
923 B
C
35 lines
923 B
C
/* 7zCrcOpt.c -- CRC32 calculation : optimized version
|
|
2009-11-23 : Igor Pavlov : Public domain */
|
|
|
|
#include "CpuArch.h"
|
|
|
|
#ifdef MY_CPU_LE
|
|
|
|
#define CRC_UPDATE_BYTE_2(crc, b) (table[((crc) ^ (b)) & 0xFF] ^ ((crc) >> 8))
|
|
|
|
UInt32 MY_FAST_CALL CrcUpdateT4(UInt32 v, const void *data, size_t size, const UInt32 *table)
|
|
{
|
|
const Byte *p = (const Byte *)data;
|
|
for (; size > 0 && ((unsigned)(ptrdiff_t)p & 3) != 0; size--, p++)
|
|
v = CRC_UPDATE_BYTE_2(v, *p);
|
|
for (; size >= 4; size -= 4, p += 4)
|
|
{
|
|
v ^= *(const UInt32 *)p;
|
|
v =
|
|
table[0x300 + (v & 0xFF)] ^
|
|
table[0x200 + ((v >> 8) & 0xFF)] ^
|
|
table[0x100 + ((v >> 16) & 0xFF)] ^
|
|
table[0x000 + ((v >> 24))];
|
|
}
|
|
for (; size > 0; size--, p++)
|
|
v = CRC_UPDATE_BYTE_2(v, *p);
|
|
return v;
|
|
}
|
|
|
|
UInt32 MY_FAST_CALL CrcUpdateT8(UInt32 v, const void *data, size_t size, const UInt32 *table)
|
|
{
|
|
return CrcUpdateT4(v, data, size, table);
|
|
}
|
|
|
|
#endif
|