strsum.c

/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*          Copyright (c) 1985-2011 AT&T Intellectual Property          *
*                      and is licensed under the                       *
*                 Eclipse Public License, Version 1.0                  *
*                    by AT&T Intellectual Property                     *
*                                                                      *
*                A copy of the License is available at                 *
*          http://www.eclipse.org/org/documents/epl-v10.html           *
*         (with md5 checksum b35adb5213ca9657e911e9befb180842)         *
*                                                                      *
*              Information and Software Systems Research               *
*                            AT&T Research                             *
*                           Florham Park NJ                            *
*                                                                      *
*                 Glenn Fowler <[email protected]>                  *
*                  David Korn <[email protected]>                   *
*                   Phong Vo <[email protected]>                    *
*                                                                      *
***********************************************************************/
#pragma prototyped
/*
 * Glenn Fowler
 * AT&T Bell Laboratories
 *
 * hash table library
 */

#include "hashlib.h"

/*
 * return a running 32 bit checksum of string s
 *
 * c is the return value from a previous
 * memsum() or strsum() call, 0 on the first call
 *
 * the result is the same on all implementations
 */

unsigned long
strsum(const char* as, register unsigned long c)
{
	register const unsigned char*	s = (const unsigned char*)as;
	register int			n;

	while (n = *s++) HASHPART(c, n);
#if LONG_MAX > 2147483647
	return(c & 0xffffffff);
#else
	return(c);
#endif
}