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64 lines
1.7 KiB
C
64 lines
1.7 KiB
C
/* 7zCrcOpt.c -- CRC32 calculation
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2010-12-01 : Igor Pavlov : Public domain */
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#include "CpuArch.h"
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#define CRC_UPDATE_BYTE_2(crc, b) (table[((crc) ^ (b)) & 0xFF] ^ ((crc) >> 8))
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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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{
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const Byte *p = (const Byte *)data;
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for (; size > 0 && ((unsigned)(ptrdiff_t)p & 3) != 0; size--, p++)
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v = CRC_UPDATE_BYTE_2(v, *p);
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for (; size >= 4; size -= 4, p += 4)
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{
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v ^= *(const UInt32 *)p;
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v =
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table[0x300 + (v & 0xFF)] ^
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table[0x200 + ((v >> 8) & 0xFF)] ^
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table[0x100 + ((v >> 16) & 0xFF)] ^
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table[0x000 + ((v >> 24))];
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}
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for (; size > 0; size--, p++)
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v = CRC_UPDATE_BYTE_2(v, *p);
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return v;
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}
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UInt32 MY_FAST_CALL CrcUpdateT8(UInt32 v, const void *data, size_t size, const UInt32 *table)
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{
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return CrcUpdateT4(v, data, size, table);
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}
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#endif
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#ifndef MY_CPU_LE
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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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{
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const Byte *p = (const Byte *)data;
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for (; size > 0 && ((unsigned)(ptrdiff_t)p & 3) != 0; size--, p++)
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v = CRC_UPDATE_BYTE_2(v, *p);
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v = CRC_UINT32_SWAP(v);
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table += 0x100;
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for (; size >= 4; size -= 4, p += 4)
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{
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v ^= *(const UInt32 *)p;
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v =
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table[0x000 + (v & 0xFF)] ^
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table[0x100 + ((v >> 8) & 0xFF)] ^
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table[0x200 + ((v >> 16) & 0xFF)] ^
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table[0x300 + ((v >> 24))];
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}
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table -= 0x100;
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v = CRC_UINT32_SWAP(v);
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for (; size > 0; size--, p++)
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v = CRC_UPDATE_BYTE_2(v, *p);
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return v;
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}
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#endif
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