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      1 /* libFLAC - Free Lossless Audio Codec library
      2  * Copyright (C) 2000,2001,2002,2003,2004,2005,2006,2007  Josh Coalson
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  *
      8  * - Redistributions of source code must retain the above copyright
      9  * notice, this list of conditions and the following disclaimer.
     10  *
     11  * - Redistributions in binary form must reproduce the above copyright
     12  * notice, this list of conditions and the following disclaimer in the
     13  * documentation and/or other materials provided with the distribution.
     14  *
     15  * - Neither the name of the Xiph.org Foundation nor the names of its
     16  * contributors may be used to endorse or promote products derived from
     17  * this software without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     21  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     22  * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR
     23  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     24  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     25  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     26  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
     27  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
     28  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
     29  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #ifndef FLAC__PRIVATE__CRC_H
     33 #define FLAC__PRIVATE__CRC_H
     34 
     35 #include "FLAC/ordinals.h"
     36 
     37 /* 8 bit CRC generator, MSB shifted first
     38 ** polynomial = x^8 + x^2 + x^1 + x^0
     39 ** init = 0
     40 */
     41 extern FLAC__byte const FLAC__crc8_table[256];
     42 #define FLAC__CRC8_UPDATE(data, crc) (crc) = FLAC__crc8_table[(crc) ^ (data)];
     43 void FLAC__crc8_update(const FLAC__byte data, FLAC__uint8 *crc);
     44 void FLAC__crc8_update_block(const FLAC__byte *data, unsigned len, FLAC__uint8 *crc);
     45 FLAC__uint8 FLAC__crc8(const FLAC__byte *data, unsigned len);
     46 
     47 /* 16 bit CRC generator, MSB shifted first
     48 ** polynomial = x^16 + x^15 + x^2 + x^0
     49 ** init = 0
     50 */
     51 extern unsigned FLAC__crc16_table[256];
     52 
     53 #define FLAC__CRC16_UPDATE(data, crc) (((((crc)<<8) & 0xffff) ^ FLAC__crc16_table[((crc)>>8) ^ (data)]))
     54 /* this alternate may be faster on some systems/compilers */
     55 #if 0
     56 #define FLAC__CRC16_UPDATE(data, crc) ((((crc)<<8) ^ FLAC__crc16_table[((crc)>>8) ^ (data)]) & 0xffff)
     57 #endif
     58 
     59 unsigned FLAC__crc16(const FLAC__byte *data, unsigned len);
     60 
     61 #endif
     62