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/* adler32.c
* Compute the Adler32 checksum (RFC 1950)
* 2003 Tomas Kukosa
* Based on code from RFC 1950 (Chapter 9. Appendix: Sample code)
*
* $Id: adler32.c,v 1.2 2003/10/02 22:44:18 guy Exp $
*
* Ethereal - Network traffic analyzer
* By Gerald Combs <gerald@ethereal.com>
* Copyright 1998 Gerald Combs
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include <string.h>
#include "adler32.h"
#define BASE 65521 /* largest prime smaller than 65536 */
/*--- update_adler32 --------------------------------------------------------*/
unsigned long update_adler32(unsigned long adler, const unsigned char *buf, int len)
{
unsigned long s1 = adler & 0xffff;
unsigned long s2 = (adler >> 16) & 0xffff;
int n;
for (n = 0; n < len; n++) {
s1 = (s1 + buf[n]) % BASE;
s2 = (s2 + s1) % BASE;
}
return (s2 << 16) + s1;
}
/*--- adler32 ---------------------------------------------------------------*/
unsigned long adler32_bytes(unsigned char *buf, int len)
{
return update_adler32(1L, buf, len);
}
/*--- adler32_str -----------------------------------------------------------*/
unsigned long adler32_str(const char *buf)
{
return update_adler32(1L, (unsigned char*)buf, strlen(buf));
}
/*---------------------------------------------------------------------------*/
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