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Annotation of sys/lib/libkern/arch/i386/bzero.S, Revision 1.1.1.1

1.1       nbrk        1: /*     $OpenBSD: bzero.S,v 1.3 2007/05/25 20:32:29 krw 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(bzero)
                     11:        pushl   %edi
                     12:        movl    8(%esp),%edi
                     13:        movl    12(%esp),%edx
                     14:
                     15:        cld                             /* set fill direction forward */
                     16:        xorl    %eax,%eax               /* set fill data to 0 */
                     17:
                     18:        /*
                     19:         * if the string is too short, it's really not worth the overhead
                     20:         * of aligning to word boundaries, etc.  So we jump to a plain
                     21:         * unaligned set.
                     22:         */
                     23:        cmpl    $16,%edx
                     24:        jb      L1
                     25:
                     26:        movl    %edi,%ecx               /* compute misalignment */
                     27:        negl    %ecx
                     28:        andl    $3,%ecx
                     29:        subl    %ecx,%edx
                     30:        rep                             /* zero until word aligned */
                     31:        stosb
                     32:
                     33:        movl    %edx,%ecx               /* zero by words */
                     34:        shrl    $2,%ecx
                     35:        andl    $3,%edx
                     36:        rep
                     37:        stosl
                     38:
                     39: L1:    movl    %edx,%ecx               /* zero remainder by bytes */
                     40:        rep
                     41:        stosb
                     42:
                     43:        popl    %edi
                     44:        ret