1/*
2 * Copyright (c) 1997 - 2000 Kungliga Tekniska H�gskolan
3 * (Royal Institute of Technology, Stockholm, Sweden).
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 *
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 *
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * 3. Neither the name of the Institute nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#include "krb5_locl.h"
35
36RCSID("$Id: crc.c 17442 2006-05-05 09:31:15Z lha $");
37
38static u_long table[256];
39
40#define CRC_GEN 0xEDB88320L
41
42void
43_krb5_crc_init_table(void)
44{
45    static int flag = 0;
46    unsigned long crc, poly;
47    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
65uint32_t
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