mirror of
https://github.com/KolibriOS/kolibrios.git
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58 lines
882 B
C
58 lines
882 B
C
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/* CRC32 function; Author PaulCodeman */
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:dword crc32Table = 0;
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:dword makeCRCTable(void)
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{
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dword i = 0;
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dword c = 0;
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dword ii = 0;
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dword crcTable = 0;
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IF (crc32Table) RETURN 0;
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crc32Table = malloc(4*256);
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crcTable = crc32Table;
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WHILE (i < 256)
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{
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c = i;
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ii = 0;
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WHILE (ii < 8)
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{
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IF (c&1)
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{
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c >>= 1;
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c ^= 0xEDB88320;
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}
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ELSE c >>= 1;
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ii++;
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}
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DSDWORD[crcTable] = c;
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crcTable += 4;
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i++;
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}
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}
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:dword crc32(dword bytes, length)
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{
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dword crc = 0;
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dword i = 0;
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byte b = 0;
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IF (!crc32Table) makeCRCTable();
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crc = 0xFFFFFFFF;
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WHILE (i < length)
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{
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b = DSBYTE[bytes];
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bytes++;
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EDX = crc^b;
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EDX &= 0xFF;
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EDX <<= 2;
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EDX += crc32Table;
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crc >>= 8;
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crc ^= DSDWORD[EDX];
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i++;
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}
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RETURN crc ^ 0xFFFFFFFF;
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}
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/* EXAMPLE
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dword str = 0;
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str = "Kevin van Zonneveld";
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crc32(str, strlen(str));
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IF (EAX == 1249991249) ExitProcess();
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*/
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