49 lines
1.2 KiB
C
49 lines
1.2 KiB
C
/*
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* Copyright (C) 2016 Felix Fietkau <nbd@nbd.name>
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*
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* Based on busybox code:
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* CRC32 table fill function
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* Copyright (C) 2006 by Rob Sullivan <cogito.ergo.cogito@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2
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* as published by the Free Software Foundation
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#ifndef __BB_CRC32_H
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#define __BB_CRC32_H
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static inline void
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crc32_filltable(uint32_t *crc_table)
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{
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uint32_t polynomial = 0xedb88320;
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uint32_t c;
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int i, j;
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for (i = 0; i < 256; i++) {
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c = i;
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for (j = 8; j; j--)
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c = (c&1) ? ((c >> 1) ^ polynomial) : (c >> 1);
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*crc_table++ = c;
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}
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}
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static inline uint32_t
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crc32_block(uint32_t val, const void *buf, unsigned len, uint32_t *crc_table)
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{
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const void *end = (uint8_t*)buf + len;
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while (buf != end) {
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val = crc_table[(uint8_t)val ^ *(uint8_t*)buf] ^ (val >> 8);
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buf = (uint8_t*)buf + 1;
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}
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return val;
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}
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#endif
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