crc.c revision 178826
1129202Scognet/* 2129202Scognet * Copyright (c) 1997 - 2000 Kungliga Tekniska H�gskolan 3129202Scognet * (Royal Institute of Technology, Stockholm, Sweden). 4129202Scognet * All rights reserved. 5129202Scognet * 6129202Scognet * Redistribution and use in source and binary forms, with or without 7129202Scognet * modification, are permitted provided that the following conditions 8129202Scognet * are met: 9129202Scognet * 10129202Scognet * 1. Redistributions of source code must retain the above copyright 11129202Scognet * notice, this list of conditions and the following disclaimer. 12129202Scognet * 13129202Scognet * 2. Redistributions in binary form must reproduce the above copyright 14129202Scognet * notice, this list of conditions and the following disclaimer in the 15129202Scognet * documentation and/or other materials provided with the distribution. 16129202Scognet * 17129202Scognet * 3. Neither the name of the Institute nor the names of its contributors 18129202Scognet * may be used to endorse or promote products derived from this software 19129202Scognet * without specific prior written permission. 20129202Scognet * 21129202Scognet * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND 22129202Scognet * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23129202Scognet * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24129202Scognet * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE 25129202Scognet * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26129202Scognet * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27129202Scognet * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28129202Scognet * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29129202Scognet * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30129202Scognet * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31129202Scognet * SUCH DAMAGE. 32129202Scognet */ 33129202Scognet 34129202Scognet#include "krb5_locl.h" 35129202Scognet 36129202ScognetRCSID("$Id: crc.c 17442 2006-05-05 09:31:15Z lha $"); 37129202Scognet 38129202Scognetstatic u_long table[256]; 39129202Scognet 40129202Scognet#define CRC_GEN 0xEDB88320L 41129202Scognet 42245650Sandrewvoid 43245650Sandrew_krb5_crc_init_table(void) 44245650Sandrew{ 45245650Sandrew static int flag = 0; 46245650Sandrew unsigned long crc, poly; 47245650Sandrew int i, j; 48245650Sandrew 49129202Scognet if(flag) return; 50245650Sandrew poly = CRC_GEN; 51129202Scognet for (i = 0; i < 256; i++) { 52129202Scognet crc = i; 53129202Scognet for (j = 8; j > 0; j--) { 54129202Scognet if (crc & 1) { 55129202Scognet crc = (crc >> 1) ^ poly; 56129202Scognet } else { 57129202Scognet crc >>= 1; 58129202Scognet } 59129202Scognet } 60129202Scognet table[i] = crc; 61129202Scognet } 62129202Scognet flag = 1; 63129202Scognet} 64129202Scognet 65129202Scognetuint32_t 66129202Scognet_krb5_crc_update (const char *p, size_t len, uint32_t res) 67129202Scognet{ 68129202Scognet while (len--) 69129202Scognet res = table[(res ^ *p++) & 0xFF] ^ (res >> 8); 70171217Speter return res & 0xFFFFFFFF; 71171217Speter} 72171217Speter