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