diff options
Diffstat (limited to 'src/libs/7zip/win/C/7zCrc.c')
-rw-r--r-- | src/libs/7zip/win/C/7zCrc.c | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/src/libs/7zip/win/C/7zCrc.c b/src/libs/7zip/win/C/7zCrc.c new file mode 100644 index 000000000..a92084961 --- /dev/null +++ b/src/libs/7zip/win/C/7zCrc.c @@ -0,0 +1,74 @@ +/* 7zCrc.c -- CRC32 calculation +2009-11-23 : Igor Pavlov : Public domain */ + +#include "7zCrc.h" +#include "CpuArch.h" + +#define kCrcPoly 0xEDB88320 + +#ifdef MY_CPU_LE +#define CRC_NUM_TABLES 8 +#else +#define CRC_NUM_TABLES 1 +#endif + +typedef UInt32 (MY_FAST_CALL *CRC_FUNC)(UInt32 v, const void *data, size_t size, const UInt32 *table); + +static CRC_FUNC g_CrcUpdate; +UInt32 g_CrcTable[256 * CRC_NUM_TABLES]; + +#if CRC_NUM_TABLES == 1 + +#define CRC_UPDATE_BYTE_2(crc, b) (table[((crc) ^ (b)) & 0xFF] ^ ((crc) >> 8)) + +static UInt32 MY_FAST_CALL CrcUpdateT1(UInt32 v, const void *data, size_t size, const UInt32 *table) +{ + const Byte *p = (const Byte *)data; + for (; size > 0; size--, p++) + v = CRC_UPDATE_BYTE_2(v, *p); + return v; +} + +#else + +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 + +UInt32 MY_FAST_CALL CrcUpdate(UInt32 v, const void *data, size_t size) +{ + return g_CrcUpdate(v, data, size, g_CrcTable); +} + +UInt32 MY_FAST_CALL CrcCalc(const void *data, size_t size) +{ + return g_CrcUpdate(CRC_INIT_VAL, data, size, g_CrcTable) ^ CRC_INIT_VAL; +} + +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 & ~((r & 1) - 1)); + g_CrcTable[i] = r; + } + #if CRC_NUM_TABLES == 1 + g_CrcUpdate = CrcUpdateT1; + #else + for (; i < 256 * CRC_NUM_TABLES; i++) + { + UInt32 r = g_CrcTable[i - 256]; + g_CrcTable[i] = g_CrcTable[r & 0xFF] ^ (r >> 8); + } + g_CrcUpdate = CrcUpdateT4; + #ifdef MY_CPU_X86_OR_AMD64 + if (!CPU_Is_InOrder()) + g_CrcUpdate = CrcUpdateT8; + #endif + #endif +} |