1/* $OpenBSD: ffs.S,v 1.4 2015/11/14 21:53:03 guenther Exp $ */ 2/* 3 * Written by J.T. Conklin <jtc@netbsd.org>. 4 * Public domain. 5 * Adapted for NetBSD/x86_64 by Frank van der Linden <fvdl@wasabisystems.com> 6 */ 7 8#include "DEFS.h" 9 10ENTRY(ffs) 11 bsfl %edi,%eax 12 jz L1 /* ZF is set if all bits are 0 */ 13 incl %eax /* bits numbered from 1, not 0 */ 14 ret 15 16 _ALIGN_TEXT 17L1: xorl %eax,%eax /* clear result */ 18 ret 19END_WEAK(ffs) 20