| 1 | #include "Types.h" |
| 2 | |
| 3 | #define CRC32_POLYNOMIAL 0x04C11DB7 |
| 4 | |
| 5 | #ifdef __CRC_OPT |
| 6 | unsigned int CRCTable[ 256 * 4]; |
| 7 | #else |
| 8 | unsigned int CRCTable[ 256 ]; |
| 9 | #endif |
| 10 | |
| 11 | u32 Reflect( u32 ref, char ch ) |
| 12 | { |
| 13 | u32 value = 0; |
| 14 | |
| 15 | // Swap bit 0 for bit 7 |
| 16 | // bit 1 for bit 6, etc. |
| 17 | for (int i = 1; i < (ch + 1); i++) |
| 18 | { |
| 19 | if(ref & 1) |
| 20 | value |= 1 << (ch - i); |
| 21 | ref >>= 1; |
| 22 | } |
| 23 | return value; |
| 24 | } |
| 25 | |
| 26 | void CRC_BuildTable() |
| 27 | { |
| 28 | u32 crc; |
| 29 | |
| 30 | for (int i = 0; i < 256; i++) |
| 31 | { |
| 32 | crc = Reflect( i, 8 ) << 24; |
| 33 | for (int j = 0; j < 8; j++) |
| 34 | crc = (crc << 1) ^ (crc & (1 << 31) ? CRC32_POLYNOMIAL : 0); |
| 35 | |
| 36 | CRCTable[i] = Reflect( crc, 32 ); |
| 37 | } |
| 38 | |
| 39 | #ifdef __CRC_OPT |
| 40 | for (int i = 0; i < 256; i++) |
| 41 | { |
| 42 | for(int j = 0; j < 3; j++) |
| 43 | { |
| 44 | CRCTable[256*(j+1) + i] = (CRCTable[256*j + i]>>8) ^ CRCTable[CRCTable[256*j + i]&0xFF]; |
| 45 | } |
| 46 | } |
| 47 | #endif |
| 48 | |
| 49 | } |
| 50 | |
| 51 | u32 CRC_Calculate( u32 crc, void *buffer, u32 count ) |
| 52 | { |
| 53 | u8 *p; |
| 54 | u32 orig = crc; |
| 55 | |
| 56 | p = (u8*) buffer; |
| 57 | |
| 58 | #ifdef __CRC_OPT |
| 59 | while(count > 3) |
| 60 | { |
| 61 | crc ^= *(unsigned int*) p; p += 4; |
| 62 | crc = CRCTable[3*256 + (crc&0xFF)] |
| 63 | ^ CRCTable[2*256 + ((crc>>8)&0xFF)] |
| 64 | ^ CRCTable[1*256 + ((crc>>16)&0xFF)] |
| 65 | ^ CRCTable[0*256 + ((crc>>24))]; |
| 66 | |
| 67 | count -= 4; |
| 68 | } |
| 69 | #endif |
| 70 | |
| 71 | while (count--) |
| 72 | crc = (crc >> 8) ^ CRCTable[(crc & 0xFF) ^ *p++]; |
| 73 | |
| 74 | return crc ^ orig; |
| 75 | } |
| 76 | |
| 77 | u32 CRC_CalculatePalette( u32 crc, void *buffer, u32 count ) |
| 78 | { |
| 79 | u8 *p; |
| 80 | u32 orig = crc; |
| 81 | |
| 82 | p = (u8*) buffer; |
| 83 | while (count--) |
| 84 | { |
| 85 | crc = (crc >> 8) ^ CRCTable[(crc & 0xFF) ^ *p++]; |
| 86 | crc = (crc >> 8) ^ CRCTable[(crc & 0xFF) ^ *p++]; |
| 87 | |
| 88 | p += 6; |
| 89 | } |
| 90 | |
| 91 | return crc ^ orig; |
| 92 | } |
| 93 | |