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37 lines
1.0 KiB
C
37 lines
1.0 KiB
C
/*
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* uncompress.c
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*
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* Piotr Fusik, 18.11.2001
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*/
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#include <zlib.h>
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int uncompress (char* dest, unsigned* destLen,
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const char* source, unsigned sourceLen)
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{
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unsigned len;
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unsigned char* ptr;
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unsigned long csum;
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/* source[0]: Compression method and flags
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bits 0 to 3: Compression method (must be Z_DEFLATED)
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bits 4 to 7: Compression info (must be <= 7)
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source[1]: Flags
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bits 0 to 4: Check bits
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bit 5: Preset dictionary (not supported, sorry)
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bits 6 to 7: Compression level
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*/
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if ((source[0] & 0x8f) != Z_DEFLATED || source[1] & 0x20)
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return Z_DATA_ERROR;
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if ((((unsigned) source[0] << 8) | (unsigned char) source[1]) % 31)
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return Z_DATA_ERROR;
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*destLen = len = inflatemem(dest, source + 2);
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ptr = (unsigned char*) source + sourceLen - 4;
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csum = adler32(adler32(0L, Z_NULL, 0), dest, len);
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if ((unsigned char) csum != ptr[3]
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|| (unsigned char) (csum >> 8) != ptr[2]
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|| (unsigned char) (csum >> 16) != ptr[1]
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|| (unsigned char) (csum >> 24) != ptr[0])
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return Z_DATA_ERROR;
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return Z_OK;
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}
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