1 /*********************************************************************** 2 * * 3 * This software is part of the ast package * 4 * Copyright (c) 1985-2007 AT&T Knowledge Ventures * 5 * and is licensed under the * 6 * Common Public License, Version 1.0 * 7 * by AT&T Knowledge Ventures * 8 * * 9 * A copy of the License is available at * 10 * http://www.opensource.org/licenses/cpl1.0.txt * 11 * (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9) * 12 * * 13 * Information and Software Systems Research * 14 * AT&T Research * 15 * Florham Park NJ * 16 * * 17 * Glenn Fowler <gsf@research.att.com> * 18 * David Korn <dgk@research.att.com> * 19 * Phong Vo <kpv@research.att.com> * 20 * * 21 ***********************************************************************/ 22 #pragma prototyped 23 /* 24 * Glenn Fowler 25 * AT&T Bell Laboratories 26 * 27 * hash table library 28 */ 29 30 #include "hashlib.h" 31 32 /* 33 * return a running 32 bit checksum of buffer b of length n 34 * 35 * c is the return value from a previous 36 * memsum() or strsum() call, 0 on the first call 37 * 38 * the result is the same on all implementations 39 */ 40 41 unsigned long 42 memsum(const void* ap, int n, register unsigned long c) 43 { 44 register const unsigned char* p = (const unsigned char*)ap; 45 register const unsigned char* e = p + n; 46 47 while (p < e) HASHPART(c, *p++); 48 #if LONG_MAX > 2147483647 49 return(c & 0xffffffff); 50 #else 51 return(c); 52 #endif 53 } 54