1 /* $OpenBSD: memchr.S,v 1.2 2014年11月29日 18:51:23 tedu Exp $ */ 2 3 /* 4 * Written by J.T. Conklin <jtc@netbsd.org>. 5 * Public domain. 6 */ 7 8#include <machine/asm.h> 9 10 ENTRY(memchr) 11 pushl %edi 12 movl 8(%esp),%edi /* string address */ 13 movl 12(%esp),%eax /* set character to search for */ 14 movl 16(%esp),%ecx /* set length of search */ 15 testl %ecx,%ecx /* test for len == 0 */ 16 jz L1 17 repne /* search! */ 18 scasb 19 jne L1 /* scan failed, return null */ 20 leal -1(%edi),%eax /* adjust result of scan */ 21 popl %edi 22 ret 23 .align 2,0x90 24 L1: xorl %eax,%eax 25 popl %edi 26 ret 27