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/* 7zCrc.c -- CRC32 init↩
2017-06-06 : Igor Pavlov : Public domain */↩
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#include "Precomp.h"↩
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#include "7zCrc.h"↩
#include "CpuArch.h"↩
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#define kCrcPoly 0xEDB88320↩
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#ifdef MY_CPU_LE↩
#define CRC_NUM_TABLES 8↩
#else↩
#define CRC_NUM_TABLES 9↩
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#define CRC_UINT32_SWAP(v) ((v >> 24) | ((v >> 8) & 0xFF00) | ((v << 8) & 0xFF0000) | (v << 24))↩
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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↩
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#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↩
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typedef UInt32 (MY_FAST_CALL *CRC_FUNC)(UInt32 v, const void *data, size_t size, const UInt32 *table);↩
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CRC_FUNC g_CrcUpdateT4;↩
CRC_FUNC g_CrcUpdateT8;↩
CRC_FUNC g_CrcUpdate;↩
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UInt32 g_CrcTable[256 * CRC_NUM_TABLES];↩
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UInt32 MY_FAST_CALL CrcUpdate(UInt32 v, const void *data, size_t size)↩
{↩
return g_CrcUpdate(v, data, size, g_CrcTable);↩
}↩
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UInt32 MY_FAST_CALL CrcCalc(const void *data, size_t size)↩
{↩
return g_CrcUpdate(CRC_INIT_VAL, data, size, g_CrcTable) ^ CRC_INIT_VAL;↩
}↩
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#define CRC_UPDATE_BYTE_2(crc, b) (table[((crc) ^ (b)) & 0xFF] ^ ((crc) >> 8))↩
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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;↩
}↩
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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 & ((UInt32)0 - (r & 1)));↩
g_CrcTable[i] = r;↩
}↩
for (i = 256; i < 256 * CRC_NUM_TABLES; i++)↩
{↩
UInt32 r = g_CrcTable[(size_t)i - 256];↩
g_CrcTable[i] = g_CrcTable[r & 0xFF] ^ (r >> 8);↩
}↩
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#if CRC_NUM_TABLES < 4↩
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g_CrcUpdate = CrcUpdateT1;↩
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#else↩
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#ifdef MY_CPU_LE↩
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g_CrcUpdateT4 = CrcUpdateT4;↩
g_CrcUpdate = CrcUpdateT4;↩
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#if CRC_NUM_TABLES >= 8↩
g_CrcUpdateT8 = CrcUpdateT8;↩
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#ifdef MY_CPU_X86_OR_AMD64↩
if (!CPU_Is_InOrder())↩
#endif↩
g_CrcUpdate = CrcUpdateT8;↩
#endif↩
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#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[(size_t)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↩
}↩