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 36 RCSID("$Id: crc.c 17442 2006-05-05 09:31:15Z lha $"); 37 38 static u_long table[256]; 39 40 #define CRC_GEN 0xEDB88320L 41 42 void 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 65 uint32_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