lib/misc/crc32.h
author "Tomas Zeman <tzeman@volny.cz>"
Wed, 16 Jan 2008 22:39:43 +0100
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/*********************************** CRC32 ***********************************/
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/* Use a type crc32_t variable to store the crc value.
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 * Initialise the variable to CRC32INIT before running the crc routine.
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 * for more details see the CRC32.C file */
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#ifndef CRC32INIT
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#define CRC32INIT 0xFFFFFFFFL /* the initializer for the 32-bit CRC */
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typedef unsigned long crc32_t; /* the type of the 32-bit CRC */
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extern const crc32_t crc32tab[]; /* a table of 32-bit CRC feedback terms */
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#ifdef __cplusplus
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inline crc32_t crc32_update (const crc32_t crc, const unsigned char octet)
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{
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  return crc32tab [(unsigned char) crc ^ octet] ^ ((crc >> 8) & 0x00FFFFFFL);
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}
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class crc32_c
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{
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private:
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  crc32_t val;
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public:
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  inline crc32_c (const crc32_t v = 0L) : val (v ^ CRC32INIT) {}
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  inline void init () { val = CRC32INIT; }
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  inline operator crc32_t () const { return val ^ CRC32INIT; }
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  inline crc32_t operator = (const crc32_c &n) {
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    return (val = n.val) ^ CRC32INIT;
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  }
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  inline crc32_t operator = (const crc32_t &n) {
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    return val = n ^ CRC32INIT, n;
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  }
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  inline void update (const unsigned char octet) {
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    val = crc32_update (val, octet);
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  }
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  crc32_t update (const unsigned char *block, int len);
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  inline crc32_t update (const char* block, int len) {
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    return update((const unsigned char*)block, len);
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  }
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};
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#else
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#define crc32_update(crc32,octet) ( crc32 = crc32tab[(unsigned char)(crc32) ^ \
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        (unsigned char)(octet) ] ^ ( ((crc32)>>8) & 0x00FFFFFFL ) )
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#endif
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#endif CRC32INIT