11849Swollman/* 21849Swollman * Copyright (c) 1993 Winning Strategies, Inc. 31849Swollman * All rights reserved. 41849Swollman * 51849Swollman * Redistribution and use in source and binary forms, with or without 61849Swollman * modification, are permitted provided that the following conditions 71849Swollman * are met: 81849Swollman * 1. Redistributions of source code must retain the above copyright 91849Swollman * notice, this list of conditions and the following disclaimer. 101849Swollman * 2. Redistributions in binary form must reproduce the above copyright 111849Swollman * notice, this list of conditions and the following disclaimer in the 121849Swollman * documentation and/or other materials provided with the distribution. 131849Swollman * 3. All advertising materials mentioning features or use of this software 141849Swollman * must display the following acknowledgement: 151849Swollman * This product includes software developed by Winning Strategies, Inc. 161849Swollman * 4. The name of the author may not be used to endorse or promote products 1797748Sschweikh * derived from this software without specific prior written permission 181849Swollman * 191849Swollman * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 201849Swollman * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 211849Swollman * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 221849Swollman * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 231849Swollman * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 241849Swollman * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 251849Swollman * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 261849Swollman * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 271849Swollman * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 281849Swollman * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 291849Swollman */ 301849Swollman 3185437Speter#include <machine/asm.h> 3293000Sobrien__FBSDID("$FreeBSD: releng/10.2/lib/libc/i386/string/ffs.S 217106 2011-01-07 16:08:40Z kib $"); 331849Swollman 341849Swollman/* 351849Swollman * ffs(value) 361849Swollman * finds the first bit set in value and returns the index of 371849Swollman * that bit. Bits are numbered starting from 1, starting at the 381849Swollman * rightmost bit. A return value of 0 means that the argument 391849Swollman * was zero. 401849Swollman * 411849Swollman * Written by: 421849Swollman * J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc. 431849Swollman */ 441849Swollman 451849SwollmanENTRY(ffs) 461849Swollman bsfl 4(%esp),%eax 471849Swollman jz L1 /* ZF is set if all bits are 0 */ 481849Swollman incl %eax /* bits numbered from 1, not 0 */ 491849Swollman ret 501849Swollman 511849Swollman .align 2 521849SwollmanL1: xorl %eax,%eax /* clear result */ 531849Swollman ret 54184548SpeterEND(ffs) 55217106Skib 56217106Skib .section .note.GNU-stack,"",%progbits 57