75 lines
1.7 KiB
C
75 lines
1.7 KiB
C
/* 7zCrc.c -- CRC32 calculation
|
|
2009-11-23 : Igor Pavlov : Public domain */
|
|
|
|
#include "7zCrc.h"
|
|
#include "CpuArch.h"
|
|
|
|
#define kCrcPoly 0xEDB88320
|
|
|
|
#ifdef MY_CPU_LE
|
|
#define CRC_NUM_TABLES 8
|
|
#else
|
|
#define CRC_NUM_TABLES 1
|
|
#endif
|
|
|
|
typedef UInt32 (MY_FAST_CALL *CRC_FUNC)(UInt32 v, const void *data, size_t size, const UInt32 *table);
|
|
|
|
static CRC_FUNC g_CrcUpdate;
|
|
UInt32 g_CrcTable[256 * CRC_NUM_TABLES];
|
|
|
|
#if CRC_NUM_TABLES == 1
|
|
|
|
#define CRC_UPDATE_BYTE_2(crc, b) (table[((crc) ^ (b)) & 0xFF] ^ ((crc) >> 8))
|
|
|
|
static UInt32 MY_FAST_CALL CrcUpdateT1(UInt32 v, const void *data, size_t size, const UInt32 *table)
|
|
{
|
|
const Byte *p = (const Byte *)data;
|
|
for (; size > 0; size--, p++)
|
|
v = CRC_UPDATE_BYTE_2(v, *p);
|
|
return v;
|
|
}
|
|
|
|
#else
|
|
|
|
UInt32 MY_FAST_CALL CrcUpdateT4(UInt32 v, const void *data, size_t size, const UInt32 *table);
|
|
UInt32 MY_FAST_CALL CrcUpdateT8(UInt32 v, const void *data, size_t size, const UInt32 *table);
|
|
|
|
#endif
|
|
|
|
UInt32 MY_FAST_CALL CrcUpdate(UInt32 v, const void *data, size_t size)
|
|
{
|
|
return g_CrcUpdate(v, data, size, g_CrcTable);
|
|
}
|
|
|
|
UInt32 MY_FAST_CALL CrcCalc(const void *data, size_t size)
|
|
{
|
|
return g_CrcUpdate(CRC_INIT_VAL, data, size, g_CrcTable) ^ CRC_INIT_VAL;
|
|
}
|
|
|
|
void MY_FAST_CALL CrcGenerateTable()
|
|
{
|
|
UInt32 i;
|
|
for (i = 0; i < 256; i++)
|
|
{
|
|
UInt32 r = i;
|
|
unsigned j;
|
|
for (j = 0; j < 8; j++)
|
|
r = (r >> 1) ^ (kCrcPoly & ~((r & 1) - 1));
|
|
g_CrcTable[i] = r;
|
|
}
|
|
#if CRC_NUM_TABLES == 1
|
|
g_CrcUpdate = CrcUpdateT1;
|
|
#else
|
|
for (; i < 256 * CRC_NUM_TABLES; i++)
|
|
{
|
|
UInt32 r = g_CrcTable[i - 256];
|
|
g_CrcTable[i] = g_CrcTable[r & 0xFF] ^ (r >> 8);
|
|
}
|
|
g_CrcUpdate = CrcUpdateT4;
|
|
#ifdef MY_CPU_X86_OR_AMD64
|
|
if (!CPU_Is_InOrder())
|
|
g_CrcUpdate = CrcUpdateT8;
|
|
#endif
|
|
#endif
|
|
}
|