global octdiv

section .text
octdiv:
        push    rbp
        mov     rbp,rsp
        push    rbx
        push    rcx
        push    rdx
        push    rsi
        push    rdi

        mov     rax,[rbp+24] ; source
        mov     rcx,[rbp+16] ; buffer
        mov     bx,3
        xor     rsi,rsi ; for counter
        xor     rdx,rdx ; for div

lstart: div     bx
        add     dx, 48
        mov     [rcx+rsi], dx
        xor     dx,dx
        inc     rsi
        cmp     rsi,11
        jg      lbreak
        cmp     ax,0
        jg      lstart
        mov     rdx,rcx
        mov     rcx,rsi
        shr     rcx,1
revert:
        mov     rdi,rsi
        sub     rdi,rcx
        mov     al,[rdx+rdi]
        mov     bl,[rdx+rcx-1]
        mov     [rdx+rdi],bl
        mov     [rdx+rcx-1],al
        loop    revert
        mov     rax,0
        jmp     lend
lbreak:
        mov     rax,1
lend:
        pop     rdi
        pop     rsi
        pop     rdx
        pop     rcx
        pop     rbx
        pop     rbp
        ret     16