1 /* 7zCrc.c -- CRC32 init
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2 2015-03-10 : Igor Pavlov : Public domain */
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9 #define kCrcPoly 0xEDB88320
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12 #define CRC_NUM_TABLES 8
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14 #define CRC_NUM_TABLES 9
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16 #define CRC_UINT32_SWAP(v) ((v >> 24) | ((v >> 8) & 0xFF00) | ((v << 8) & 0xFF0000) | (v << 24))
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18 UInt32 MY_FAST_CALL CrcUpdateT1_BeT4(UInt32 v, const void *data, size_t size, const UInt32 *table);
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19 UInt32 MY_FAST_CALL CrcUpdateT1_BeT8(UInt32 v, const void *data, size_t size, const UInt32 *table);
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23 UInt32 MY_FAST_CALL CrcUpdateT4(UInt32 v, const void *data, size_t size, const UInt32 *table);
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24 UInt32 MY_FAST_CALL CrcUpdateT8(UInt32 v, const void *data, size_t size, const UInt32 *table);
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27 typedef UInt32 (MY_FAST_CALL *CRC_FUNC)(UInt32 v, const void *data, size_t size, const UInt32 *table);
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29 CRC_FUNC g_CrcUpdateT4;
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30 CRC_FUNC g_CrcUpdateT8;
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31 CRC_FUNC g_CrcUpdate;
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33 UInt32 g_CrcTable[256 * CRC_NUM_TABLES];
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35 UInt32 MY_FAST_CALL CrcUpdate(UInt32 v, const void *data, size_t size)
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37 return g_CrcUpdate(v, data, size, g_CrcTable);
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40 UInt32 MY_FAST_CALL CrcCalc(const void *data, size_t size)
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42 return g_CrcUpdate(CRC_INIT_VAL, data, size, g_CrcTable) ^ CRC_INIT_VAL;
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45 #define CRC_UPDATE_BYTE_2(crc, b) (table[((crc) ^ (b)) & 0xFF] ^ ((crc) >> 8))
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47 UInt32 MY_FAST_CALL CrcUpdateT1(UInt32 v, const void *data, size_t size, const UInt32 *table)
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49 const Byte *p = (const Byte *)data;
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50 const Byte *pEnd = p + size;
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51 for (; p != pEnd; p++)
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52 v = CRC_UPDATE_BYTE_2(v, *p);
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56 void MY_FAST_CALL CrcGenerateTable()
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59 for (i = 0; i < 256; i++)
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63 for (j = 0; j < 8; j++)
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64 r = (r >> 1) ^ (kCrcPoly & ~((r & 1) - 1));
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67 for (; i < 256 * CRC_NUM_TABLES; i++)
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69 UInt32 r = g_CrcTable[i - 256];
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70 g_CrcTable[i] = g_CrcTable[r & 0xFF] ^ (r >> 8);
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73 #if CRC_NUM_TABLES < 4
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75 g_CrcUpdate = CrcUpdateT1;
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81 g_CrcUpdateT4 = CrcUpdateT4;
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82 g_CrcUpdate = CrcUpdateT4;
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84 #if CRC_NUM_TABLES >= 8
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85 g_CrcUpdateT8 = CrcUpdateT8;
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87 #ifdef MY_CPU_X86_OR_AMD64
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88 if (!CPU_Is_InOrder())
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89 g_CrcUpdate = CrcUpdateT8;
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96 UInt32 k = 0x01020304;
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97 const Byte *p = (const Byte *)&k;
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98 if (p[0] == 4 && p[1] == 3)
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100 g_CrcUpdateT4 = CrcUpdateT4;
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101 g_CrcUpdate = CrcUpdateT4;
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102 #if CRC_NUM_TABLES >= 8
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103 g_CrcUpdateT8 = CrcUpdateT8;
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104 // g_CrcUpdate = CrcUpdateT8;
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107 else if (p[0] != 1 || p[1] != 2)
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108 g_CrcUpdate = CrcUpdateT1;
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112 for (i = 256 * CRC_NUM_TABLES - 1; i >= 256; i--)
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114 UInt32 x = g_CrcTable[i - 256];
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115 g_CrcTable[i] = CRC_UINT32_SWAP(x);
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117 g_CrcUpdateT4 = CrcUpdateT1_BeT4;
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118 g_CrcUpdate = CrcUpdateT1_BeT4;
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119 #if CRC_NUM_TABLES >= 8
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120 g_CrcUpdateT8 = CrcUpdateT1_BeT8;
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121 // g_CrcUpdate = CrcUpdateT1_BeT8;
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