Modified source engine (2017) developed by valve and leaked in 2020. Not for commercial purporses
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/* XzCrc64.c -- CRC64 calculation
2011-06-28 : Igor Pavlov : Public domain */
#include "Precomp.h"
#include "XzCrc64.h"
#include "CpuArch.h"
#define kCrc64Poly UINT64_CONST(0xC96C5795D7870F42)
#ifdef MY_CPU_LE
#define CRC_NUM_TABLES 4
#else
#define CRC_NUM_TABLES 5
#define CRC_UINT64_SWAP(v) \
((v >> 56) | \
((v >> 40) & ((UInt64)0xFF << 8)) | \
((v >> 24) & ((UInt64)0xFF << 16)) | \
((v >> 8) & ((UInt64)0xFF << 24)) | \
((v << 8) & ((UInt64)0xFF << 32)) | \
((v << 24) & ((UInt64)0xFF << 40)) | \
((v << 40) & ((UInt64)0xFF << 48)) | \
(v << 56))
UInt64 MY_FAST_CALL XzCrc64UpdateT1_BeT4(UInt64 v, const void *data, size_t size, const UInt64 *table);
#endif
#ifndef MY_CPU_BE
UInt64 MY_FAST_CALL XzCrc64UpdateT4(UInt64 v, const void *data, size_t size, const UInt64 *table);
#endif
typedef UInt64 (MY_FAST_CALL *CRC_FUNC)(UInt64 v, const void *data, size_t size, const UInt64 *table);
static CRC_FUNC g_Crc64Update;
UInt64 g_Crc64Table[256 * CRC_NUM_TABLES];
UInt64 MY_FAST_CALL Crc64Update(UInt64 v, const void *data, size_t size)
{
return g_Crc64Update(v, data, size, g_Crc64Table);
}
UInt64 MY_FAST_CALL Crc64Calc(const void *data, size_t size)
{
return g_Crc64Update(CRC64_INIT_VAL, data, size, g_Crc64Table) ^ CRC64_INIT_VAL;
}
void MY_FAST_CALL Crc64GenerateTable()
{
UInt32 i;
for (i = 0; i < 256; i++)
{
UInt64 r = i;
unsigned j;
for (j = 0; j < 8; j++)
r = (r >> 1) ^ (kCrc64Poly & ~((r & 1) - 1));
g_Crc64Table[i] = r;
}
for (; i < 256 * CRC_NUM_TABLES; i++)
{
UInt64 r = g_Crc64Table[i - 256];
g_Crc64Table[i] = g_Crc64Table[r & 0xFF] ^ (r >> 8);
}
#ifdef MY_CPU_LE
g_Crc64Update = XzCrc64UpdateT4;
#else
{
#ifndef MY_CPU_BE
UInt32 k = 1;
if (*(const Byte *)&k == 1)
g_Crc64Update = XzCrc64UpdateT4;
else
#endif
{
for (i = 256 * CRC_NUM_TABLES - 1; i >= 256; i--)
{
UInt64 x = g_Crc64Table[i - 256];
g_Crc64Table[i] = CRC_UINT64_SWAP(x);
}
g_Crc64Update = XzCrc64UpdateT1_BeT4;
}
}
#endif
}