.text
        .global main
main:
        mov     $1, %edx
readloop:
        call    readi32
        jb      fin
        cmp     $0, %eax
        jnl     pushstack
popstack:
        mov     %eax, %ebx
        // ebx = -ebx
        mov     $0, %eax
        sub     %ebx, %eax
        mov     %eax, %ebx
        cmp     $0, %ebx
        je      emptycase

        mov     pers_stack+4(, %ebx, 8), %eax
        cmp     $0, %eax
        je      emptycase
        mov     pers_stack(, %ebx, 8), %eax
        call    writei32
        mov     pers_stack+4(, %ebx, 8), %eax
        mov     %eax, %ecx
        mov     (%ecx), %eax
        mov     %eax, pers_stack(, %edx, 8)
        mov     4(%ecx), %eax
        mov     %eax, pers_stack+4(, %edx, 8)
        inc     %edx
        jmp     readloop
emptycase:
        mov     $-1, %eax
        call    writei32
        jmp     readloop
pushstack:
        mov     %eax, %ebx
        call    readi32
        test    %ebx, %ebx
        jz      zerocase
        mov     %eax, pers_stack(, %edx, 8)
        lea     pers_stack(, %ebx, 8), %ebx
        mov     %ebx, pers_stack+4(, %edx, 8)
        inc     %edx
        jmp    readloop
zerocase:
        mov     %eax, pers_stack(, %edx, 8)
        mov     $pers_stack, %eax
        mov     %eax, pers_stack+4(, %edx, 8)
        inc     %edx
        jmp   readloop
fin:
        call    finish


        .data
pers_stack:
        // [(int x)(parent)]
        .skip   8008