1/* $OpenBSD: ffs.S,v 1.2 1996/09/27 06:47:45 mickey Exp $ */ 2 3/* 4 * Written by J.T. Conklin <jtc@netbsd.org>. 5 * Public domain. 6 */ 7 8#include <machine/asm.h> 9 10ENTRY(ffs) 11 bsfl 4(%esp),%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 2 17L1: xorl %eax,%eax /* clear result */ 18 ret 19