source: trunk/minix/lib/i386/string/_strnlen.s@ 9

!       _strnlen()                                      Author: Kees J. Bot
!                                                               1 Jan 1994
.sect .text; .sect .rom; .sect .data; .sect .bss

! size_t _strnlen(const char *s, size_t ecx)
!       Return the length of a string.
!
.sect .text
.define __strnlen
        .align  16
__strnlen:
        push    ebp
        mov     ebp, esp
        push    edi
        mov     edi, 8(ebp)     ! edi = string
        xorb    al, al          ! Look for a zero byte
        mov     edx, ecx        ! Save maximum count
        cmpb    cl, 1           ! 'Z' bit must be clear if ecx = 0
        cld
        repne
        scasb                   ! Look for zero
        jne     no0
        inc     ecx             ! Don't count zero byte
no0:    mov     eax, edx
        sub     eax, ecx        ! Compute bytes scanned
        pop     edi
        pop     ebp
        ret