1 /* 7zCrc.c -- CRC32 init 2 2017-06-06 : Igor Pavlov : Public domain */ 3 4 #include "Precomp.h" 5 6 #include "7zCrc.h" 7 #include "CpuArch.h" 8 9 #define kCrcPoly 0xEDB88320 10 11 #ifdef MY_CPU_LE 12 #define CRC_NUM_TABLES 8 13 #else 14 #define CRC_NUM_TABLES 9 15 16 #define CRC_UINT32_SWAP(v) ((v >> 24) | ((v >> 8) & 0xFF00) | ((v << 8) & 0xFF0000) | (v << 24)) 17 18 UInt32 MY_FAST_CALL CrcUpdateT1_BeT4(UInt32 v, const void *data, size_t size, const UInt32 *table); 19 UInt32 MY_FAST_CALL CrcUpdateT1_BeT8(UInt32 v, const void *data, size_t size, const UInt32 *table); 20 #endif 21 22 #ifndef MY_CPU_BE 23 UInt32 MY_FAST_CALL CrcUpdateT4(UInt32 v, const void *data, size_t size, const UInt32 *table); 24 UInt32 MY_FAST_CALL CrcUpdateT8(UInt32 v, const void *data, size_t size, const UInt32 *table); 25 #endif 26 27 typedef UInt32 (MY_FAST_CALL *CRC_FUNC)(UInt32 v, const void *data, size_t size, const UInt32 *table); 28 29 CRC_FUNC g_CrcUpdateT4; 30 CRC_FUNC g_CrcUpdateT8; 31 CRC_FUNC g_CrcUpdate; 32 33 UInt32 g_CrcTable[256 * CRC_NUM_TABLES]; 34 35 UInt32 MY_FAST_CALL CrcUpdate(UInt32 v, const void *data, size_t size) 36 { 37 return g_CrcUpdate(v, data, size, g_CrcTable); 38 } 39 40 UInt32 MY_FAST_CALL CrcCalc(const void *data, size_t size) 41 { 42 return g_CrcUpdate(CRC_INIT_VAL, data, size, g_CrcTable) ^ CRC_INIT_VAL; 43 } 44 45 #define CRC_UPDATE_BYTE_2(crc, b) (table[((crc) ^ (b)) & 0xFF] ^ ((crc) >> 8)) 46 47 UInt32 MY_FAST_CALL CrcUpdateT1(UInt32 v, const void *data, size_t size, const UInt32 *table) 48 { 49 const Byte *p = (const Byte *)data; 50 const Byte *pEnd = p + size; 51 for (; p != pEnd; p++) 52 v = CRC_UPDATE_BYTE_2(v, *p); 53 return v; 54 } 55 56 void MY_FAST_CALL CrcGenerateTable() 57 { 58 UInt32 i; 59 for (i = 0; i < 256; i++) 60 { 61 UInt32 r = i; 62 unsigned j; 63 for (j = 0; j < 8; j++) 64 r = (r >> 1) ^ (kCrcPoly & ((UInt32)0 - (r & 1))); 65 g_CrcTable[i] = r; 66 } 67 for (i = 256; i < 256 * CRC_NUM_TABLES; i++) 68 { 69 UInt32 r = g_CrcTable[(size_t)i - 256]; 70 g_CrcTable[i] = g_CrcTable[r & 0xFF] ^ (r >> 8); 71 } 72 73 #if CRC_NUM_TABLES < 4 74 75 g_CrcUpdate = CrcUpdateT1; 76 77 #else 78 79 #ifdef MY_CPU_LE 80 81 g_CrcUpdateT4 = CrcUpdateT4; 82 g_CrcUpdate = CrcUpdateT4; 83 84 #if CRC_NUM_TABLES >= 8 85 g_CrcUpdateT8 = CrcUpdateT8; 86 87 #ifdef MY_CPU_X86_OR_AMD64 88 if (!CPU_Is_InOrder()) 89 #endif 90 g_CrcUpdate = CrcUpdateT8; 91 #endif 92 93 #else 94 { 95 #ifndef MY_CPU_BE 96 UInt32 k = 0x01020304; 97 const Byte *p = (const Byte *)&k; 98 if (p[0] == 4 && p[1] == 3) 99 { 100 g_CrcUpdateT4 = CrcUpdateT4; 101 g_CrcUpdate = CrcUpdateT4; 102 #if CRC_NUM_TABLES >= 8 103 g_CrcUpdateT8 = CrcUpdateT8; 104 g_CrcUpdate = CrcUpdateT8; 105 #endif 106 } 107 else if (p[0] != 1 || p[1] != 2) 108 g_CrcUpdate = CrcUpdateT1; 109 else 110 #endif 111 { 112 for (i = 256 * CRC_NUM_TABLES - 1; i >= 256; i--) 113 { 114 UInt32 x = g_CrcTable[(size_t)i - 256]; 115 g_CrcTable[i] = CRC_UINT32_SWAP(x); 116 } 117 g_CrcUpdateT4 = CrcUpdateT1_BeT4; 118 g_CrcUpdate = CrcUpdateT1_BeT4; 119 #if CRC_NUM_TABLES >= 8 120 g_CrcUpdateT8 = CrcUpdateT1_BeT8; 121 g_CrcUpdate = CrcUpdateT1_BeT8; 122 #endif 123 } 124 } 125 #endif 126 127 #endif 128 } 129
