72 lines
2.3 KiB
C
72 lines
2.3 KiB
C
/*
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* Copyright (c) 1997 - 2000 Kungliga Tekniska Högskolan
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* (Royal Institute of Technology, Stockholm, Sweden).
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include "krb5_locl.h"
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RCSID("$Id: crc.c,v 1.9 2000/08/03 01:45:14 assar Exp $");
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static u_long table[256];
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#define CRC_GEN 0xEDB88320L
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void
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_krb5_crc_init_table(void)
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{
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static int flag = 0;
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unsigned long crc, poly;
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int i, j;
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if(flag) return;
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poly = CRC_GEN;
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for (i = 0; i < 256; i++) {
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crc = i;
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for (j = 8; j > 0; j--) {
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if (crc & 1) {
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crc = (crc >> 1) ^ poly;
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} else {
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crc >>= 1;
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}
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}
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table[i] = crc;
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}
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flag = 1;
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}
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u_int32_t
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_krb5_crc_update (const char *p, size_t len, u_int32_t res)
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{
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while (len--)
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res = table[(res ^ *p++) & 0xFF] ^ (res >> 8);
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return res & 0xFFFFFFFF;
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}
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