MAX_RADIX EQU 18
jmp main

;ds:si - input buf
proc_writeln:
    pusha
    cld
    mov ah, 0Eh
    write:
        lodsb
        test al,al
        jz exit_write
        int 10h
        jmp write
    exit_write:
        ;newline
        mov al, 0Dh
        int 10h
        mov al, 0Ah
        int 10h
        popa
        ret


;es:di - output buf
;cx - max buffer size
proc_readln:
    pusha
    cld
    read:
        mov ah, 0
        int 16h
        cmp al, 13
        jz exit_read
        stosb
        loop read

    exit_read:
        mov al, 0
        stosb

        mov ah, 0Eh

        ;newline
        mov al, 0Dh
        int 10h
        mov al, 0Ah
        int 10h

        popa
        ret

;ds:si - char buf
;es:di - integer buf
proc_to_integer:
    pusha
    cld
    transform:
        lodsb
        test al,al
        jz transform_exit

        cmp al, 2Fh             ;;validation start
        jng transform_error
        cmp al, 39h
        jg transform_error      ;;validation end

        sub al, 30h
        stosb
        jmp transform

    transform_error:
        stc

    transform_exit:
        popa
        ret

;es:di - output buf
proc_read_integer:
    pusha
    call proc_readln
    mov ax, es
    mov ds, ax
    mov si, di
    call proc_to_integer
    jc read_error

    popa
    ret

    read_error:
        lea si, Err_not_integer
        call proc_writeln
        popa
        call proc_read_integer
        ret


main:
    mov ax, cs
    mov ds, ax
    lea si, Invite_1
    call proc_writeln

    mov ax, cs
    mov es, ax
    lea di, op_1
    call proc_read_integer

    lea si, Invite_2
    call proc_writeln

    lea di, op_2
    call proc_read_integer

    lea si, Res_message
    call proc_writeln

    lea si, op_1
    call proc_writeln

    lea si, op_2
    call proc_writeln

    mov ah, 4Ch
    int 21h

Invite_1 db 'Enter first number: ', 0
Invite_2 db 'Enter second number: ', 0
Res_message db 'Result is: ', 0
Err_not_integer db 'This is not a number. Try again: ', 0
op_1 db MAX_RADIX dup(0)
op_2 db MAX_RADIX dup(0)
res db MAX_RADIX dup(0)