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/* 7zCrc.c -- CRC32 init
2015-03-10 : Igor Pavlov : Public domain */
#include "Precomp.h"
#include "7zCrc.h"
#include "CpuArch.h"
#define kCrcPoly 0xEDB88320
#ifdef MY_CPU_LE
#define CRC_NUM_TABLES 8
#else
#define CRC_NUM_TABLES 9
#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);
UInt32 MY_FAST_CALL CrcUpdateT1_BeT8(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);
UInt32 MY_FAST_CALL CrcUpdateT8(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_CrcUpdateT4;
CRC_FUNC g_CrcUpdateT8;
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;
}
#define CRC_UPDATE_BYTE_2(crc, b) (table[((crc) ^ (b)) & 0xFF] ^ ((crc) >> 8))
UInt32 MY_FAST_CALL CrcUpdateT1(UInt32 v, const void *data, size_t size, const UInt32 *table)
{
const Byte *p = (const Byte *)data;
const Byte *pEnd = p + size;
for (; p != pEnd; p++)
v = CRC_UPDATE_BYTE_2(v, *p);
return v;
}
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);
}
#if CRC_NUM_TABLES < 4
g_CrcUpdate = CrcUpdateT1;
#else
#ifdef MY_CPU_LE
g_CrcUpdateT4 = CrcUpdateT4;
g_CrcUpdate = CrcUpdateT4;
#if CRC_NUM_TABLES >= 8
g_CrcUpdateT8 = CrcUpdateT8;
#ifdef MY_CPU_X86_OR_AMD64
if (!CPU_Is_InOrder())
g_CrcUpdate = CrcUpdateT8;
#endif
#endif
#else
{
#ifndef MY_CPU_BE
UInt32 k = 0x01020304;
const Byte *p = (const Byte *)&k;
if (p[0] == 4 && p[1] == 3)
{
g_CrcUpdateT4 = CrcUpdateT4;
g_CrcUpdate = CrcUpdateT4;
#if CRC_NUM_TABLES >= 8
g_CrcUpdateT8 = CrcUpdateT8;
// g_CrcUpdate = CrcUpdateT8;
#endif
}
else if (p[0] != 1 || p[1] != 2)
g_CrcUpdate = CrcUpdateT1;
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_CrcUpdateT4 = CrcUpdateT1_BeT4;
g_CrcUpdate = CrcUpdateT1_BeT4;
#if CRC_NUM_TABLES >= 8
g_CrcUpdateT8 = CrcUpdateT1_BeT8;
// g_CrcUpdate = CrcUpdateT1_BeT8;
#endif
}
}
#endif
#endif
}
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