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/* 7zCrcT8.c -- CRC32 calculation with 8 tables
2008-03-19
Igor Pavlov
Public domain */
#include "7zCrc.h"
#define kCrcPoly 0xEDB88320
#define CRC_NUM_TABLES 8
UInt32 g_CrcTable[256 * CRC_NUM_TABLES];
void MY_FAST_CALL CrcGenerateTable()
{
UInt32 i;
for (i = 0; i < 256; i++)
{
UInt32 r = i;
int j;
for (j = 0; j < 8; j++)
r = (r >> 1) ^ (kCrcPoly & ~((r & 1) - 1));
g_CrcTable[i] = r;
}
#if CRC_NUM_TABLES > 1
for (; i < 256 * CRC_NUM_TABLES; i++)
{
UInt32 r = g_CrcTable[i - 256];
g_CrcTable[i] = g_CrcTable[r & 0xFF] ^ (r >> 8);
}
#endif
}
UInt32 MY_FAST_CALL CrcUpdateT8(UInt32 v, const void *data, size_t size, const UInt32 *table);
UInt32 MY_FAST_CALL CrcUpdate(UInt32 v, const void *data, size_t size)
{
return CrcUpdateT8(v, data, size, g_CrcTable);
}
UInt32 MY_FAST_CALL CrcCalc(const void *data, size_t size)
{
return CrcUpdateT8(CRC_INIT_VAL, data, size, g_CrcTable) ^ 0xFFFFFFFF;
}
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