mirror of https://github.com/vitalif/e2fsprogs
46 lines
1.1 KiB
C
46 lines
1.1 KiB
C
/*
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* crc16.h - CRC-16 routine
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*
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* Implements the standard CRC-16:
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* Width 16
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* Poly 0x8005 (x16 + x15 + x2 + 1)
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* Init 0
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*
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* Copyright (c) 2005 Ben Gardner <bgardner@wabtec.com>
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*
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* This source code is licensed under the GNU General Public License,
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* Version 2. See the file COPYING for more details.
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*/
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#ifndef __CRC16_H
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#define __CRC16_H
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#include <ext2fs/ext2_types.h>
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extern __u16 const crc16_table[256];
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#ifdef WORDS_BIGENDIAN
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/* for an unknown reason, PPC treats __u16 as signed and keeps doing sign
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* extension on the value. Instead, use only the low 16 bits of an
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* unsigned int for holding the CRC value to avoid this.
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*/
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typedef unsigned crc16_t;
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static inline crc16_t crc16_byte(crc16_t crc, const unsigned char data)
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{
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return (((crc >> 8) & 0xffU) ^ crc16_table[(crc ^ data) & 0xffU]) &
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0x0000ffffU;
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}
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#else
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typedef __u16 crc16_t;
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static inline crc16_t crc16_byte(crc16_t crc, const unsigned char data)
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{
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return (crc >> 8) ^ crc16_table[(crc ^ data) & 0xff];
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}
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#endif
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extern crc16_t crc16(crc16_t crc, const void *buffer, unsigned int len);
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#endif /* __CRC16_H */
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