hash_log2.c revision 189291
150472Speter/*- 239145Sbrian * Copyright (c) 1990, 1993, 1994 3149Srgrimes * The Regents of the University of California. All rights reserved. 4105053Srwatson * 5105055Srwatson * This code is derived from software contributed to Berkeley by 6105055Srwatson * Margo Seltzer. 7105055Srwatson * 837Srgrimes * Redistribution and use in source and binary forms, with or without 925376Sjkh * modification, are permitted provided that the following conditions 1037Srgrimes * are met: 1137Srgrimes * 1. Redistributions of source code must retain the above copyright 121280Sjkh * notice, this list of conditions and the following disclaimer. 1337Srgrimes * 2. Redistributions in binary form must reproduce the above copyright 14170566Sceri * notice, this list of conditions and the following disclaimer in the 15105055Srwatson * documentation and/or other materials provided with the distribution. 1698696Sdes * 4. Neither the name of the University nor the names of its contributors 1786510Sgshapiro * may be used to endorse or promote products derived from this software 1886510Sgshapiro * without specific prior written permission. 19241823Smarcel * 20105131Srwatson * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 2141441Sdillon * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22255597Sdes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23126810Smlaier * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24126810Smlaier * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25130953Smlaier * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26147062Sbrooks * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 271642Sache * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 2814594Sphk * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 2929082Sbrian * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30155350Srwatson * SUCH DAMAGE. 3185455Sache */ 32218046Spjd 338573Srgrimes#if defined(LIBC_SCCS) && !defined(lint) 348539Sachestatic char sccsid[] = "@(#)hash_log2.c 8.2 (Berkeley) 5/31/94"; 35#endif /* LIBC_SCCS and not lint */ 36#include <sys/cdefs.h> 37__FBSDID("$FreeBSD: head/lib/libc/db/hash/hash_log2.c 189291 2009-03-02 23:47:18Z delphij $"); 38 39#include <sys/types.h> 40 41#include <db.h> 42 43u_int32_t 44__log2(u_int32_t num) 45{ 46 u_int32_t i, limit; 47 48 limit = 1; 49 for (i = 0; limit < num; limit = limit << 1, i++); 50 return (i); 51} 52