| /* 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; |
| /* FIXME |
| #ifdef MY_CPU_X86_OR_AMD64 |
| if (!CPU_Is_InOrder()) |
| g_CrcUpdate = CrcUpdateT8; |
| #endif |
| */ |
| #endif |
| } |