repo sync | baa3858 | 2013-07-26 17:53:31 -0700 | [diff] [blame] | 1 | /* 7zCrc.c -- CRC32 calculation
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| 2 | 2009-11-23 : Igor Pavlov : Public domain */
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| 3 |
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| 4 | #include "7zCrc.h"
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| 5 | #include "CpuArch.h"
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| 6 |
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| 7 | #define kCrcPoly 0xEDB88320
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| 8 |
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| 9 | #ifdef MY_CPU_LE
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| 10 | #define CRC_NUM_TABLES 8
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| 11 | #else
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| 12 | #define CRC_NUM_TABLES 1
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| 13 | #endif
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| 14 |
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| 15 | typedef UInt32 (MY_FAST_CALL *CRC_FUNC)(UInt32 v, const void *data, size_t size, const UInt32 *table);
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| 16 |
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| 17 | static CRC_FUNC g_CrcUpdate;
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| 18 | UInt32 g_CrcTable[256 * CRC_NUM_TABLES];
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| 19 |
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| 20 | #if CRC_NUM_TABLES == 1
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| 21 |
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| 22 | #define CRC_UPDATE_BYTE_2(crc, b) (table[((crc) ^ (b)) & 0xFF] ^ ((crc) >> 8))
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| 23 |
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| 24 | static UInt32 MY_FAST_CALL CrcUpdateT1(UInt32 v, const void *data, size_t size, const UInt32 *table)
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| 25 | {
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| 26 | const Byte *p = (const Byte *)data;
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| 27 | for (; size > 0; size--, p++)
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| 28 | v = CRC_UPDATE_BYTE_2(v, *p);
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| 29 | return v;
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| 30 | }
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| 31 |
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| 32 | #else
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| 33 |
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| 34 | UInt32 MY_FAST_CALL CrcUpdateT4(UInt32 v, const void *data, size_t size, const UInt32 *table);
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| 35 | UInt32 MY_FAST_CALL CrcUpdateT8(UInt32 v, const void *data, size_t size, const UInt32 *table);
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| 36 |
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| 37 | #endif
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| 38 |
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| 39 | UInt32 MY_FAST_CALL CrcUpdate(UInt32 v, const void *data, size_t size)
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| 40 | {
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| 41 | return g_CrcUpdate(v, data, size, g_CrcTable);
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| 42 | }
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| 43 |
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| 44 | UInt32 MY_FAST_CALL CrcCalc(const void *data, size_t size)
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| 45 | {
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| 46 | return g_CrcUpdate(CRC_INIT_VAL, data, size, g_CrcTable) ^ CRC_INIT_VAL;
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| 47 | }
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| 48 |
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| 49 | void MY_FAST_CALL CrcGenerateTable()
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| 50 | {
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| 51 | UInt32 i;
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| 52 | for (i = 0; i < 256; i++)
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| 53 | {
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| 54 | UInt32 r = i;
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| 55 | unsigned j;
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| 56 | for (j = 0; j < 8; j++)
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| 57 | r = (r >> 1) ^ (kCrcPoly & ~((r & 1) - 1));
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| 58 | g_CrcTable[i] = r;
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| 59 | }
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| 60 | #if CRC_NUM_TABLES == 1
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| 61 | g_CrcUpdate = CrcUpdateT1;
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| 62 | #else
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| 63 | for (; i < 256 * CRC_NUM_TABLES; i++)
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| 64 | {
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| 65 | UInt32 r = g_CrcTable[i - 256];
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| 66 | g_CrcTable[i] = g_CrcTable[r & 0xFF] ^ (r >> 8);
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| 67 | }
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| 68 | g_CrcUpdate = CrcUpdateT4;
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| 69 | #ifdef MY_CPU_X86_OR_AMD64
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| 70 | if (!CPU_Is_InOrder())
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| 71 | g_CrcUpdate = CrcUpdateT8;
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| 72 | #endif
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| 73 | #endif
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| 74 | }
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