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/* 7zCrc.c -- CRC32 init
2013-11-12 : Igor Pavlov : Public domain */
#include "Precomp.h"
#include "7zCrc.h"
#include "CpuArch.h"
#define kCrcPoly 0xEDB88320
#ifdef MY_CPU_X86_OR_AMD64
#define CRC_NUM_TABLES 8
UInt32 MY_FAST_CALL CrcUpdateT8(UInt32 v, const void *data, size_t size, const UInt32 *table);
#elif defined(MY_CPU_LE)
#define CRC_NUM_TABLES 4
#else
#define CRC_NUM_TABLES 5
#define CRC_UINT32_SWAP(v) ((v >> 24) | ((v >> 8) & 0xFF00) | ((v << 8) & 0xFF0000) | (v << 24))
UInt32 MY_FAST_CALL CrcUpdateT1_BeT4(UInt32 v, const void *data, size_t size, const UInt32 *table);
#endif
#ifndef MY_CPU_BE
UInt32 MY_FAST_CALL CrcUpdateT4(UInt32 v, const void *data, size_t size, const UInt32 *table);
#endif
typedef UInt32 (MY_FAST_CALL *CRC_FUNC)(UInt32 v, const void *data, size_t size, const UInt32 *table);
CRC_FUNC g_CrcUpdate;
UInt32 g_CrcTable[256 * CRC_NUM_TABLES];
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;
}
for (; i < 256 * CRC_NUM_TABLES; i++)
{
UInt32 r = g_CrcTable[i - 256];
g_CrcTable[i] = g_CrcTable[r & 0xFF] ^ (r >> 8);
}
#ifdef MY_CPU_LE
g_CrcUpdate = CrcUpdateT4;
#if CRC_NUM_TABLES == 8
if (!CPU_Is_InOrder())
g_CrcUpdate = CrcUpdateT8;
#endif
#else
{
#ifndef MY_CPU_BE
UInt32 k = 1;
if (*(const Byte *)&k == 1)
g_CrcUpdate = CrcUpdateT4;
else
#endif
{
for (i = 256 * CRC_NUM_TABLES - 1; i >= 256; i--)
{
UInt32 x = g_CrcTable[i - 256];
g_CrcTable[i] = CRC_UINT32_SWAP(x);
}
g_CrcUpdate = CrcUpdateT1_BeT4;
}
}
#endif
}
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