root/lib/libc/arch/amd64/string/memchr.S
/*
 * Written by J.T. Conklin <jtc@netbsd.org>.
 * Public domain.
 * Adapted for NetBSD/x86_64 by Frank van der Linden <fvdl@wasabisystems.com>
 */

#include "DEFS.h"

ENTRY(memchr)
        RETGUARD_SETUP(memchr, r11)
        movb    %sil,%al                /* set character to search for */
        movq    %rdx,%rcx               /* set length of search */
        testq   %rcx,%rcx               /* test for len == 0 */
        jz      L1
        cld                             /* set search forward */
        repne                           /* search! */
        scasb
        jne     L1                      /* scan failed, return null */
        leaq    -1(%rdi),%rax           /* adjust result of scan */
        jmp L2
L1:     xorq    %rax,%rax
L2:     RETGUARD_CHECK(memchr, r11)
        ret
END_STRONG(memchr)