Home | History | Annotate | Line # | Download | only in adventure
crc.c revision 1.2 
      1 /*	$NetBSD: crc.c,v 1.2 1995/03/21 12:04:59 cgd Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * This code is derived from software contributed to Berkeley by
      8  * James W. Williams of the University of Maryland.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *	This product includes software developed by the University of
     21  *	California, Berkeley and its contributors.
     22  * 4. Neither the name of the University nor the names of its contributors
     23  *    may be used to endorse or promote products derived from this software
     24  *    without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     36  * SUCH DAMAGE.
     37  */
     38 
     39 #ifndef lint
     40 #if 0
     41 static char sccsid[] = "@(#)crc.c	8.1 (Berkeley) 5/31/93";
     42 static char ORIGINAL_sccsid[] = "@(#)crc.c	5.2 (Berkeley) 4/4/91";
     43 #else
     44 static char rcsid[] = "$NetBSD: crc.c,v 1.2 1995/03/21 12:04:59 cgd Exp $";
     45 #endif
     46 #endif /* not lint */
     47 
     48 typedef	unsigned long	u_long;
     49 
     50 u_long crctab[] = {
     51 	0x7fffffff,
     52 	0x77073096,  0xee0e612c,  0x990951ba,  0x076dc419,  0x706af48f,
     53 	0xe963a535,  0x9e6495a3,  0x0edb8832,  0x79dcb8a4,  0xe0d5e91e,
     54 	0x97d2d988,  0x09b64c2b,  0x7eb17cbd,  0xe7b82d07,  0x90bf1d91,
     55 	0x1db71064,  0x6ab020f2,  0xf3b97148,  0x84be41de,  0x1adad47d,
     56 	0x6ddde4eb,  0xf4d4b551,  0x83d385c7,  0x136c9856,  0x646ba8c0,
     57 	0xfd62f97a,  0x8a65c9ec,  0x14015c4f,  0x63066cd9,  0xfa0f3d63,
     58 	0x8d080df5,  0x3b6e20c8,  0x4c69105e,  0xd56041e4,  0xa2677172,
     59 	0x3c03e4d1,  0x4b04d447,  0xd20d85fd,  0xa50ab56b,  0x35b5a8fa,
     60 	0x42b2986c,  0xdbbbc9d6,  0xacbcf940,  0x32d86ce3,  0x45df5c75,
     61 	0xdcd60dcf,  0xabd13d59,  0x26d930ac,  0x51de003a,  0xc8d75180,
     62 	0xbfd06116,  0x21b4f4b5,  0x56b3c423,  0xcfba9599,  0xb8bda50f,
     63 	0x2802b89e,  0x5f058808,  0xc60cd9b2,  0xb10be924,  0x2f6f7c87,
     64 	0x58684c11,  0xc1611dab,  0xb6662d3d,  0x76dc4190,  0x01db7106,
     65 	0x98d220bc,  0xefd5102a,  0x71b18589,  0x06b6b51f,  0x9fbfe4a5,
     66 	0xe8b8d433,  0x7807c9a2,  0x0f00f934,  0x9609a88e,  0xe10e9818,
     67 	0x7f6a0dbb,  0x086d3d2d,  0x91646c97,  0xe6635c01,  0x6b6b51f4,
     68 	0x1c6c6162,  0x856530d8,  0xf262004e,  0x6c0695ed,  0x1b01a57b,
     69 	0x8208f4c1,  0xf50fc457,  0x65b0d9c6,  0x12b7e950,  0x8bbeb8ea,
     70 	0xfcb9887c,  0x62dd1ddf,  0x15da2d49,  0x8cd37cf3,  0xfbd44c65,
     71 	0x4db26158,  0x3ab551ce,  0xa3bc0074,  0xd4bb30e2,  0x4adfa541,
     72 	0x3dd895d7,  0xa4d1c46d,  0xd3d6f4fb,  0x4369e96a,  0x346ed9fc,
     73 	0xad678846,  0xda60b8d0,  0x44042d73,  0x33031de5,  0xaa0a4c5f,
     74 	0xdd0d7cc9,  0x5005713c,  0x270241aa,  0xbe0b1010,  0xc90c2086,
     75 	0x5768b525,  0x206f85b3,  0xb966d409,  0xce61e49f,  0x5edef90e,
     76 	0x29d9c998,  0xb0d09822,  0xc7d7a8b4,  0x59b33d17,  0x2eb40d81,
     77 	0xb7bd5c3b,  0xc0ba6cad,  0xedb88320,  0x9abfb3b6,  0x03b6e20c,
     78 	0x74b1d29a,  0xead54739,  0x9dd277af,  0x04db2615,  0x73dc1683,
     79 	0xe3630b12,  0x94643b84,  0x0d6d6a3e,  0x7a6a5aa8,  0xe40ecf0b,
     80 	0x9309ff9d,  0x0a00ae27,  0x7d079eb1,  0xf00f9344,  0x8708a3d2,
     81 	0x1e01f268,  0x6906c2fe,  0xf762575d,  0x806567cb,  0x196c3671,
     82 	0x6e6b06e7,  0xfed41b76,  0x89d32be0,  0x10da7a5a,  0x67dd4acc,
     83 	0xf9b9df6f,  0x8ebeeff9,  0x17b7be43,  0x60b08ed5,  0xd6d6a3e8,
     84 	0xa1d1937e,  0x38d8c2c4,  0x4fdff252,  0xd1bb67f1,  0xa6bc5767,
     85 	0x3fb506dd,  0x48b2364b,  0xd80d2bda,  0xaf0a1b4c,  0x36034af6,
     86 	0x41047a60,  0xdf60efc3,  0xa867df55,  0x316e8eef,  0x4669be79,
     87 	0xcb61b38c,  0xbc66831a,  0x256fd2a0,  0x5268e236,  0xcc0c7795,
     88 	0xbb0b4703,  0x220216b9,  0x5505262f,  0xc5ba3bbe,  0xb2bd0b28,
     89 	0x2bb45a92,  0x5cb36a04,  0xc2d7ffa7,  0xb5d0cf31,  0x2cd99e8b,
     90 	0x5bdeae1d,  0x9b64c2b0,  0xec63f226,  0x756aa39c,  0x026d930a,
     91 	0x9c0906a9,  0xeb0e363f,  0x72076785,  0x05005713,  0x95bf4a82,
     92 	0xe2b87a14,  0x7bb12bae,  0x0cb61b38,  0x92d28e9b,  0xe5d5be0d,
     93 	0x7cdcefb7,  0x0bdbdf21,  0x86d3d2d4,  0xf1d4e242,  0x68ddb3f8,
     94 	0x1fda836e,  0x81be16cd,  0xf6b9265b,  0x6fb077e1,  0x18b74777,
     95 	0x88085ae6,  0xff0f6a70,  0x66063bca,  0x11010b5c,  0x8f659eff,
     96 	0xf862ae69,  0x616bffd3,  0x166ccf45,  0xa00ae278,  0xd70dd2ee,
     97 	0x4e048354,  0x3903b3c2,  0xa7672661,  0xd06016f7,  0x4969474d,
     98 	0x3e6e77db,  0xaed16a4a,  0xd9d65adc,  0x40df0b66,  0x37d83bf0,
     99 	0xa9bcae53,  0xdebb9ec5,  0x47b2cf7f,  0x30b5ffe9,  0xbdbdf21c,
    100 	0xcabac28a,  0x53b39330,  0x24b4a3a6,  0xbad03605,  0xcdd70693,
    101 	0x54de5729,  0x23d967bf,  0xb3667a2e,  0xc4614ab8,  0x5d681b02,
    102 	0x2a6f2b94,  0xb40bbe37,  0xc30c8ea1,  0x5a05df1b,  0x2d02ef8d
    103 };
    104 
    105 /*
    106  * crc --
    107  *      Compute a POSIX.2 checksum.  This routine modified by Jim Gillogly
    108  *      to work on sequential data rather than on a file.  Initial call to
    109  *      crc_start initializes the sum, and subsequent calls to crc update
    110  *      it.
    111  */
    112 
    113 u_long crcval;
    114 int step;
    115 
    116 crc_start()
    117 {
    118 	crcval = step = 0;
    119 }
    120 
    121 u_long crc(ptr, nr) /* Process nr bytes at a time; ptr points to them */
    122 char *ptr;
    123 int nr;
    124 {
    125 	register int i;
    126 	register char *p;
    127 
    128 	while (nr > 0)
    129 		for (p = ptr; nr--; ++p)
    130 		{
    131 			if (!(i = crcval >> 24 ^ *p))
    132 			{
    133 				i = step++;
    134 				if (step >= sizeof(crctab)/sizeof(crctab[0]))
    135 					step = 0;
    136 			}
    137 			crcval = (crcval << 8) ^ crctab[i];
    138 		}
    139 	return crcval & 0xffffffff;               /* Mask to 32 bits. */
    140 }
    141