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Annotation of sys/lib/libkern/arch/amd64/memchr.S, Revision 1.1

1.1     ! nbrk        1: /*
        !             2:  * Written by J.T. Conklin <jtc@netbsd.org>.
        !             3:  * Public domain.
        !             4:  * Adapted for NetBSD/x86_64 by Frank van der Linden <fvdl@wasabisystems.com>
        !             5:  */
        !             6:
        !             7: #include <machine/asm.h>
        !             8:
        !             9: #if defined(LIBC_SCCS)
        !            10:        RCSID("$NetBSD: memchr.S,v 1.1 2001/06/19 00:22:46 fvdl Exp $")
        !            11: #endif
        !            12:
        !            13: ENTRY(memchr)
        !            14:        movb    %sil,%al                /* set character to search for */
        !            15:        movq    %rdx,%rcx               /* set length of search */
        !            16:        testq   %rcx,%rcx               /* test for len == 0 */
        !            17:        jz      L1
        !            18:        cld                             /* set search forward */
        !            19:        repne                           /* search! */
        !            20:        scasb
        !            21:        jne     L1                      /* scan failed, return null */
        !            22:        leaq    -1(%rdi),%rax           /* adjust result of scan */
        !            23:        ret
        !            24: L1:    xorq    %rax,%rax
        !            25:        ret