source: trunk/minix/lib/i386/string/_strncat.s@ 10

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

! char *_strncat(char *s1, const char *s2, size_t edx)
!       Append string s2 to s1.
!
.sect .text
.define __strncat
        .align  16
__strncat:
        push    ebp
        mov     ebp, esp
        push    esi
        push    edi
        mov     edi, 8(ebp)     ! String s1
        mov     ecx, -1
        xorb    al, al          ! Null byte
        cld
        repne
        scasb                   ! Look for the zero byte in s1
        dec     edi             ! Back one up (and clear 'Z' flag)
        push    edi             ! Save end of s1
        mov     edi, 12(ebp)    ! edi = string s2
        mov     ecx, edx        ! Maximum count
        repne
        scasb                   ! Look for the end of s2
        jne     no0
        inc     ecx             ! Exclude null byte
no0:    sub     edx, ecx        ! Number of bytes in s2
        mov     ecx, edx
        mov     esi, 12(ebp)    ! esi = string s2
        pop     edi             ! edi = end of string s1
        rep
        movsb                   ! Copy bytes
        stosb                   ! Add a terminating null
        mov     eax, 8(ebp)     ! Return s1
        pop     edi
        pop     esi
        pop     ebp
        ret