158f0484fSRodney W. Grimes /*- 2ef5d438eSPaul Traina * Copyright (c) 1990, 1993, 1994 358f0484fSRodney W. Grimes * The Regents of the University of California. All rights reserved. 458f0484fSRodney W. Grimes * 558f0484fSRodney W. Grimes * This code is derived from software contributed to Berkeley by 658f0484fSRodney W. Grimes * Margo Seltzer. 758f0484fSRodney W. Grimes * 858f0484fSRodney W. Grimes * Redistribution and use in source and binary forms, with or without 958f0484fSRodney W. Grimes * modification, are permitted provided that the following conditions 1058f0484fSRodney W. Grimes * are met: 1158f0484fSRodney W. Grimes * 1. Redistributions of source code must retain the above copyright 1258f0484fSRodney W. Grimes * notice, this list of conditions and the following disclaimer. 1358f0484fSRodney W. Grimes * 2. Redistributions in binary form must reproduce the above copyright 1458f0484fSRodney W. Grimes * notice, this list of conditions and the following disclaimer in the 1558f0484fSRodney W. Grimes * documentation and/or other materials provided with the distribution. 1658f0484fSRodney W. Grimes * 4. Neither the name of the University nor the names of its contributors 1758f0484fSRodney W. Grimes * may be used to endorse or promote products derived from this software 1858f0484fSRodney W. Grimes * without specific prior written permission. 1958f0484fSRodney W. Grimes * 2058f0484fSRodney W. Grimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 2158f0484fSRodney W. Grimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 2258f0484fSRodney W. Grimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 2358f0484fSRodney W. Grimes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 2458f0484fSRodney W. Grimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 2558f0484fSRodney W. Grimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 2658f0484fSRodney W. Grimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 2758f0484fSRodney W. Grimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 2858f0484fSRodney W. Grimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 2958f0484fSRodney W. Grimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 3058f0484fSRodney W. Grimes * SUCH DAMAGE. 3158f0484fSRodney W. Grimes */ 3258f0484fSRodney W. Grimes 3358f0484fSRodney W. Grimes #if defined(LIBC_SCCS) && !defined(lint) 34ef5d438eSPaul Traina static char sccsid[] = "@(#)hash_log2.c 8.2 (Berkeley) 5/31/94"; 3558f0484fSRodney W. Grimes #endif /* LIBC_SCCS and not lint */ 368fb3f3f6SDavid E. O'Brien #include <sys/cdefs.h> 378fb3f3f6SDavid E. O'Brien __FBSDID("$FreeBSD$"); 3858f0484fSRodney W. Grimes 39ef5d438eSPaul Traina #include <db.h> 40f60486b3SXin LI #include "hash.h" 41f60486b3SXin LI #include "page.h" 42f60486b3SXin LI #include "extern.h" 43ef5d438eSPaul Traina 44ef5d438eSPaul Traina u_int32_t 450ac22237SXin LI __log2(u_int32_t num) 4658f0484fSRodney W. Grimes { 478fb3f3f6SDavid E. O'Brien u_int32_t i, limit; 4858f0484fSRodney W. Grimes 4958f0484fSRodney W. Grimes limit = 1; 5058f0484fSRodney W. Grimes for (i = 0; limit < num; limit = limit << 1, i++); 5158f0484fSRodney W. Grimes return (i); 5258f0484fSRodney W. Grimes } 53