section .bss
    num1 resb 2
    num2 resb 2
    res resb 2
    op resb 2

section .data
    equal db ' = '
    nwln db 0xa

section .text
    global _start

_start:
    Loop:
; Read First Number
    mov eax, 3      ; System Call (Read)
    mov ebx, 0      ; File Descriptor (stdin)
    mov ecx, num1   ; Move data into 'num1'
    mov edx, 2
    int 0x80        ; Call Kernel

; Check for '.' to end the loop
    mov al, [num1]
    cmp al, '.'
    je End

; Read Operator
    mov eax, 3      ; System Call (Read)
    mov ebx, 0      ; File Descriptor (stdin)
    mov ecx, op     ; Move data into 'op'
    mov edx, 2
    int 0x80        ; Call Kernel

; Read Second Number
    mov eax, 3      ; System Call (Read)
    mov ebx, 0      ; File Descriptor (stdin)
    mov ecx, num2   ; Move data into 'num2'
    mov edx, 2
    int 0x80        ; Call Kernel

; Check operator
    mov al, [op]

    cmp al, '+'
    je Plus
    cmp al, '-'
    je Minus
    cmp al, '*'
    je Multiply
    cmp al, '/'
    je Divide

;------------------------------------------------------------;
Plus:
    call Addition
    jmp End

Addition:
; Move x and y to registry
    mov ax, [num1]
    sub ax, '0'
    mov bx, [num2]
    sub bx, '0'

; Add ebx to eax
    add ax, bx
    add ax, '0'

; Move value in eax to [res]
    mov [res], ax
    call Print
ret

;------------------------------------------------------------;
Minus:
    call Subtraction
    jmp End

Subtraction:
; Move x and y to registry
    mov ax, [num1]
    sub ax, '0'
    mov bx, [num2]
    sub bx, '0'

; Subtract ebx from eax
    sub ax, bx
    add ax, '0'

; Move value in eax to [res]
    mov [res], ax

    call Print
ret

;------------------------------------------------------------;
Multiply:
    call Multiplication
    jmp End

Multiplication:
; Move x and y to registry
    mov ax, [num1]
    sub ax, '0'
    mov bx, [num2]
    sub bx, '0'

; Multiply ax with bx
    mul bx
    add ax, '0'

; Move value in eax to [res]
    mov [res], ax

    call Print
ret

;------------------------------------------------------------;
Divide:
    call Division
    ;jmp End

Division:
; Move x and y to registry
    mov al, [num1]
    sub al, '0'
    mov bl, [num2]
    sub bl, '0'

; Multiply ax with bx
    div bl
    add al, '0'

; Move value in eax to [res]
    mov [res], ax

    call Print
ret

;------------------------------------------------------------;
Print:
; Write First Number
    mov eax, 4     ; System Call (Write)
    mov ebx, 1     ; File Descriptor (stdout)
    mov ecx, num1  ; Write 'num1'
    mov edx, 2
    int 0x80       ; Call Kernel
; Write Operator
    mov eax, 4     ; System Call (Write)
    mov ebx, 1     ; File Descriptor (stdout)
    mov ecx, op    ; Write 'op'
    mov edx, 2
    int 0x80       ; Call Kernel
; Write Second Number
    mov eax, 4     ; System Call (Write)
    mov ebx, 1     ; File Descriptor (stdout)
    mov ecx, num2  ; Write 'num2'
    mov edx, 1
    int 0x80       ; Call Kernel
; Write Equal Sign
    mov eax, 4     ; System Call (Write)
    mov ebx, 1     ; File Descriptor (stdout)
    mov ecx, equal ; Write 'equal'
    mov edx, 3
    int 0x80       ; Call Kernel
; Write Result
    mov eax, 4     ; System Call (Write)
    mov ebx, 1     ; File Descriptor (stdout)
    mov ecx, res   ; Write 'res'
    mov edx, 1
    int 0x80       ; Call Kernel
;New Line
    mov eax, 4     ; System Call (Write)
    mov ebx, 1     ; File Descriptor (stdout)
    mov ecx, nwln   ; Write ' '
    mov edx, 1
    int 0x80       ; Call Kernel
jmp Loop

;------------------------------------------------------------;
End:
    mov eax,1       ; System Call (sys_exit)
    int 0x80        ; Call Kernel