1 /* $OpenBSD: ffs.S,v 1.3 2005/08/07 11:30:38 espie Exp $ */ 2 /* 3 * Written by J.T. Conklin <jtc (at) netbsd.org>. 4 * Public domain. 5 */ 6 7 #include <machine/asm.h> 8 9 ENTRY(ffs) 10 bsfl 4(%esp),%eax 11 jz L1 /* ZF is set if all bits are 0 */ 12 incl %eax /* bits numbered from 1, not 0 */ 13 ret 14 15 .align 2 16 L1: xorl %eax,%eax /* clear result */ 17 ret 18 END(ffs) 19
