Details | Last modification | View Log | RSS feed
| Rev | Author | Line No. | Line |
|---|---|---|---|
| 7740 | pavelyakov | 1 | /* CRC32 function; Author PaulCodeman */ |
| 2 | :dword crc32Table = 0; |
||
| 3 | :dword makeCRCTable(void) |
||
| 4 | { |
||
| 5 | dword i = 0; |
||
| 6 | dword c = 0; |
||
| 7 | dword ii = 0; |
||
| 8 | dword crcTable = 0; |
||
| 9 | IF (crc32Table) RETURN 0; |
||
| 10 | crc32Table = malloc(4*256); |
||
| 11 | crcTable = crc32Table; |
||
| 12 | WHILE (i < 256) |
||
| 13 | { |
||
| 14 | c = i; |
||
| 15 | ii = 0; |
||
| 16 | WHILE (ii < 8) |
||
| 17 | { |
||
| 18 | IF (c&1) |
||
| 19 | { |
||
| 20 | c >>= 1; |
||
| 21 | c ^= 0xEDB88320; |
||
| 22 | } |
||
| 23 | ELSE c >>= 1; |
||
| 24 | ii++; |
||
| 25 | } |
||
| 26 | DSDWORD[crcTable] = c; |
||
| 27 | crcTable += 4; |
||
| 28 | i++; |
||
| 29 | } |
||
| 30 | } |
||
| 31 | :dword crc32(dword bytes, length) |
||
| 32 | { |
||
| 33 | dword crc = 0; |
||
| 34 | dword i = 0; |
||
| 35 | byte b = 0; |
||
| 36 | IF (!crc32Table) makeCRCTable(); |
||
| 37 | crc = 0xFFFFFFFF; |
||
| 38 | WHILE (i < length) |
||
| 39 | { |
||
| 40 | b = DSBYTE[bytes]; |
||
| 41 | bytes++; |
||
| 42 | EDX = crc^b; |
||
| 43 | EDX &= 0xFF; |
||
| 44 | EDX <<= 2; |
||
| 45 | EDX += crc32Table; |
||
| 46 | crc >>= 8; |
||
| 47 | crc ^= DSDWORD[EDX]; |
||
| 48 | i++; |
||
| 49 | } |
||
| 50 | RETURN crc ^ 0xFFFFFFFF; |
||
| 51 | } |
||
| 52 | |||
| 53 | /* EXAMPLE |
||
| 54 | dword str = 0; |
||
| 55 | str = "Kevin van Zonneveld"; |
||
| 56 | crc32(str, strlen(str)); |
||
| 57 | IF (EAX == 1249991249) ExitProcess(); |
||
| 58 | */ |