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693 user890104 1 
/*
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 * CRC32 functions
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 * Based on public domain implementation by Finn Yannick Jacobs.
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 */
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/* Written and copyright 1999 by Finn Yannick Jacobs
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 * No rights were reserved to this, so feel free to
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 * manipulate or do with it, what you want or desire :)
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 */
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#include "crc32.h"
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/* crc32table[] built by crc32_init() */
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static unsigned long crc32table[256];
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/* Calculate crc32. Little endian.
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 * Standard seed is 0xffffffff or 0.
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 * Some implementations xor result with 0xffffffff after calculation.
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 */
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uint32_t crc32(void *data, unsigned int len, uint32_t seed) {
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	uint8_t *d = data;
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	while (len--) {
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		seed = ((seed >> 8) & 0x00FFFFFF) ^ crc32table [(seed ^ *d++) & 0xFF];
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	}
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	return seed;
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}
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/* Calculate crc32table */
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void crc32_init() {
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	uint32_t poly = 0xEDB88320L;
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	uint32_t crc;
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	int i, j;
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	for (i = 0; i < 256; ++i) {
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		crc = i;
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		for (j = 8; j > 0; --j) {
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			crc = (crc >> 1) ^ ((crc & 1) ? poly : 0);
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		}
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		crc32table[i] = crc;
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	}
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}