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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)
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include <wsutil/adler32.h>
#ifdef HAVE_ZLIBNG
#include <zlib-ng.h>
#else
#ifdef HAVE_ZLIB
#include <zlib.h>
#endif /* HAVE_ZLIB */
#endif
#include <string.h>
#define BASE 65521 /* largest prime smaller than 65536 */
/*--- update_adler32 --------------------------------------------------------*/
uint32_t update_adler32(uint32_t adler, const uint8_t *buf, size_t len)
{
#if defined (HAVE_ZLIB) || defined (HAVE_ZLIBNG)
#ifdef HAVE_ZLIBNG
return (uint32_t)zng_adler32(adler, buf, len);
#else
return (uint32_t)adler32(adler, buf, len);
#endif
#endif
uint32_t s1 = adler & 0xffff;
uint32_t s2 = (adler >> 16) & 0xffff;
size_t n;
for (n = 0; n < len; n++) {
s1 = (s1 + buf[n]) % BASE;
s2 = (s2 + s1) % BASE;
}
return (s2 << 16) + s1;
}
/*--- adler32 ---------------------------------------------------------------*/
uint32_t adler32_bytes(const uint8_t *buf, size_t len)
{
return update_adler32(1, buf, len);
}
/*--- adler32_str -----------------------------------------------------------*/
uint32_t adler32_str(const char *buf)
{
return update_adler32(1, (const uint8_t*)buf, strlen(buf));
}
/*---------------------------------------------------------------------------*/
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local Variables:
* c-basic-offset: 2
* tab-width: 8
* indent-tabs-mode: nil
* End:
*
* ex: set shiftwidth=2 tabstop=8 expandtab:
* :indentSize=2:tabSize=8:noTabs=true:
*/
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