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Annotation of sys/lib/libkern/arch/amd64/strlen.S, Revision 1.1.1.1

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: strlen.S,v 1.1 2001/06/19 00:22:47 fvdl Exp $")
                     11: #endif
                     12:
                     13: ENTRY(strlen)
                     14:        cld                             /* set search forward */
                     15:        xorl    %eax,%eax               /* set search for null terminator */
                     16:        movq    $-1,%rcx                /* set search for lots of characters */
                     17:        repne                           /* search! */
                     18:        scasb
                     19:        notq    %rcx                    /* get length by taking complement */
                     20:        leaq    -1(%rcx),%rax           /* and subtracting one */
                     21:        ret