1 /* $NetBSD: crc.c,v 1.1.1.1 2011/04/13 18:15:32 elric Exp $ */
2
3 /*
4 * Copyright (c) 1997 - 2000 Kungliga Tekniska Högskolan
5 * (Royal Institute of Technology, Stockholm, Sweden).
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 *
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 *
19 * 3. Neither the name of the Institute nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36 #include "krb5_locl.h"
37
38 static u_long table[256];
39
40 #define CRC_GEN 0xEDB88320L
41
42 void
_krb5_crc_init_table(void)43 _krb5_crc_init_table(void)
44 {
45 static int flag = 0;
46 unsigned long crc, poly;
47 unsigned int i, j;
48
49 if(flag) return;
50 poly = CRC_GEN;
51 for (i = 0; i < 256; i++) {
52 crc = i;
53 for (j = 8; j > 0; j--) {
54 if (crc & 1) {
55 crc = (crc >> 1) ^ poly;
56 } else {
57 crc >>= 1;
58 }
59 }
60 table[i] = crc;
61 }
62 flag = 1;
63 }
64
65 uint32_t
_krb5_crc_update(const char * p,size_t len,uint32_t res)66 _krb5_crc_update (const char *p, size_t len, uint32_t res)
67 {
68 while (len--)
69 res = table[(res ^ *p++) & 0xFF] ^ (res >> 8);
70 return res & 0xFFFFFFFF;
71 }
72