data segment

    prompt1 db "Enter first number: $"
    prompt2 db "Enter second number: $"

    input1        dw 8 dup("$")
    packed1       db 4 dup(?)

    input2        dw 8 dup("$")
    packed2       db 4 dup(?)

    resultmessage db "Result: $"
    result        db 4 dup(?)
    resultascii   dw 4 dup(?)

    newline       db 13, 10, "$"


ends

stack segment
    dw   128  dup(0)
ends

code segment
start:

    mov ax, data
    mov ds, ax
    mov es, ax

    lea dx, prompt1
    mov ah, 9
    int 21h        ; print prompt1


    mov cx, 8
    mov si, offset input1


    inloop1:
    mov ah, 01     ; input1
    int 21h
    mov [si], al
    inc si
    loop inloop1

    xor ax, ax

    mov ah, 09
    mov dx, offset newline
    int 21h        ; print newline

    lea dx, prompt2
    mov ah, 9
    int 21h        ; print prompt2

    mov cx, 8
    mov di, offset input2



    inloop2:
    mov ah, 01     ; input2
    int 21h
    mov [di], al
    inc di
    loop inloop2



    ; ascii to packed bcd
    xor ax, ax
    mov ax, input1
    and ax, 0f0fh
    mov cl, 4
    shl al, cl
    add al, ah
    mov packed1, al

    xor ax, ax
    mov si,offset input1
    mov ax, [si+2]
    and ax, 0f0fh
    mov cl, 4
    shl al, cl
    add al, ah
    mov si,offset packed1
    mov [si+1], al


    xor ax, ax
    mov si,offset input1
    mov ax, [si+4]
    and ax, 0f0fh
    mov cl, 4
    shl al, cl
    add al, ah
    mov si,offset packed1
    mov [si+2], al


    xor ax, ax
    mov si,offset input1
    mov ax, [si+6]
    and ax, 0f0fh
    mov cl, 4
    shl al, cl
    add al, ah
    mov si,offset packed1
    mov [si+3], al




    xor ax, ax
    mov ax, input2
    and ax, 0f0fh
    mov cl, 4
    shl al, cl
    add al, ah
    mov packed2, al


    xor ax, ax
    mov si,offset input2
    mov ax, [si+2]
    and ax, 0f0fh
    mov cl, 4
    shl al, cl
    add al, ah
    mov si,offset packed2
    mov [si+1], al

    xor ax, ax
    mov si,offset input2
    mov ax, [si+4]
    and ax, 0f0fh
    mov cl, 4
    shl al, cl
    add al, ah
    mov si,offset packed2
    mov [si+2], al

    xor ax, ax
    mov si,offset input2
    mov ax, [si+6]
    and ax, 0f0fh
    mov cl, 4
    shl al, cl
    add al, ah
    mov si,offset packed2
    mov [si+3], al


    ; packed bcd addition
    xor ax, ax
    mov si, offset packed1
    mov di, offset packed2
    mov bx, offset result

    mov al, [si+3]
    add al, [di+3]
    daa
    mov [bx+3], al

    mov al, [si+2]
    adc al, [di+2]
    daa
    mov [bx+2], al


    mov al, [si+1]
    adc al, [di+1]
    daa
    mov [bx+1], al

    mov al,[si]
    adc al, [di]
    daa
    mov [bx], al



    ; packed bcd to ascii
    xor ax, ax
    mov al, result
    mov ah, al
    and al, 0fh
    mov cl, 4
    shr ah, cl
    or ax, 3030h
    xchg ah,al
    mov resultascii, ax

    xor ax, ax

    xor ax, ax
    mov si, offset result
    mov al, [si+1]
    mov ah, al
    and al, 0fh
    mov cl, 4
    shr ah, cl
    or ax, 3030h
    mov si,offset resultascii
    xchg ah,al
    mov [si+2], ax


    xor ax, ax
    mov si, offset result
    mov al, [si+2]
    mov ah, al
    and al, 0fh
    mov cl, 4
    shr ah, cl
    or ax, 3030h
    mov si,offset resultascii
    xchg ah,al
    mov [si+4], ax


    xor ax, ax
    mov si, offset result
    mov al, [si+3]
    mov ah, al
    and al, 0fh
    mov cl, 4
    shr ah, cl
    or ax, 3030h
    mov si,offset resultascii
    xchg ah,al
    mov [si+6], ax


    xor ax, ax

    mov ah, 09
    mov dx, offset newline
    int 21h        ; print newline

    lea dx, resultmessage
    mov ah, 9
    int 21h        ; print resultmessage



    ;reverse the number
   ; mov si,offset resultascii;
   ; mov al,[si]
   ; mov ah,[si+1]
   ; mov [si],ah
   ; mov [si+1],al

    lea dx, resultascii
    mov ah, 9
    int 21h        ; print result



    ; wait for any key....
    mov ah, 1
    int 21h

    mov ax, 4c00h ; exit to operating system.
    int 21h

ends

end start