1/* $OpenBSD: ffs.S,v 1.6 2018/07/03 23:14:05 mortimer 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 RETGUARD_SETUP(ffs, r11) 12 bsfl %edi,%eax 13 jz L1 /* ZF is set if all bits are 0 */ 14 incl %eax /* bits numbered from 1, not 0 */ 15 jmp L2 16 17 _ALIGN_TEXT 18L1: xorl %eax,%eax /* clear result */ 19L2: RETGUARD_CHECK(ffs, r11) 20 ret 21END(ffs) 22.protected ffs 23