1 /* 2 * Copyright (c) 1997 - 2000 Kungliga Tekniska Högskolan 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 static u_long table[256]; 37 38 #define CRC_GEN 0xEDB88320L 39 40 void 41 _krb5_crc_init_table(void) 42 { 43 static int flag = 0; 44 unsigned long crc, poly; 45 unsigned int i, j; 46 47 if(flag) return; 48 poly = CRC_GEN; 49 for (i = 0; i < 256; i++) { 50 crc = i; 51 for (j = 8; j > 0; j--) { 52 if (crc & 1) { 53 crc = (crc >> 1) ^ poly; 54 } else { 55 crc >>= 1; 56 } 57 } 58 table[i] = crc; 59 } 60 flag = 1; 61 } 62 63 uint32_t 64 _krb5_crc_update (const char *p, size_t len, uint32_t res) 65 { 66 while (len--) 67 res = table[(res ^ *p++) & 0xFF] ^ (res >> 8); 68 return res & 0xFFFFFFFF; 69 } 70