/* * Copyright (c) 1993 Winning Strategies, Inc. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by Winning Strategies, Inc. * 4. The name of the author may not be used to endorse or promote products * derived from this software withough specific prior written permission * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * * $Id: ffs.s,v 1.4 1993/08/16 17:06:30 jtc Exp $ */ #if defined(LIBC_RCS) && !defined(lint) .asciz "$Id: ffs.s,v 1.4 1993/08/16 17:06:30 jtc Exp $" #endif /* LIBC_RCS and not lint */ #include "DEFS.h" /* * ffs(value) * finds the first bit set in value and returns the index of * that bit. Bits are numbered starting from 1, starting at the * rightmost bit. A return value of 0 means that the argument * was zero. * * Written by: * J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc. */ ENTRY(ffs) bsfl 4(%esp),%eax jz L1 /* ZF is set if all bits are 0 */ incl %eax /* bits numbered from 1, not 0 */ ret .align 2 L1: xorl %eax,%eax /* clear result */ ret