SYS_EXIT equ 1 ; Allocation if information for better understanding of what certain numbers do
SYS_READ equ 3
SYS_WRITE equ 4
STDIN equ 0
STDOUT equ 1

section .data
msg1 db "= "
len1 equ $- msg1

msg2 db "Inside Add"
len2 equ $- msg2

msg3 db "Inside Sub"
len3 equ $- msg3

msg4 db "Debug"
len4 equ $- msg4

section .bss
    var1 resb 2
    op resb 2
    var2 resb 2
    res resb 2

section .text

global _start
_start:

CheckOp:
;Reads STDIN
mov eax,3
mov ebx,0
mov ecx, var1
mov edx, 2
int 80h

mov al, [var1]
cmp al, '.' ;will hold as a place stopper for the string loop
je end

;Reads STDIN
mov eax,3
mov ebx,0
mov ecx, op
mov edx, 2
int 80h

;Reads STDIN
mov eax,3
mov ebx,0
mov ecx, var2
mov edx, 1
int 80h

;;output
mov eax,4
mov ebx,1
mov ecx, var1
mov edx, 2
int 80h

mov eax,4
mov ebx,1
mov ecx, op
mov edx, 2
int 80h

mov eax,4
mov ebx,1
mov ecx, var2
mov edx, 2
int 80h

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

mov al, [op]

cmp al,'+' ; if addition, jump to callADD (addition procedure call)
je callADD

cmp al,'-'
je callSUB

callADD:
call ADD

callSUB:
call SUB

ADD:
;Debug Message
mov eax,4
mov ebx,1
mov ecx, msg2
mov edx, len2
int 80h
; moving the first number to eax register and second number to ebx
 ; and subtracting ascii '0' to convert it into a decimal number
 mov al, [var1]
 sub al, '0'
 mov bl, [var2]
 sub bl, '0'
 ; add eax and ebx
 add al, bl
 ; add '0' to to convert the sum from decimal to ASCII
 add al, '0'
 ; storing the sum in memory location res
 mov [res], al

mov eax,4 ;Prints equals sign
mov ebx,1
mov ecx, msg1
mov edx, len1
int 80h

mov eax,4 ;Prints answer
mov ebx,1
mov ecx, res
mov edx, 2
int 80h
jmp CheckOp


SUB:
mov eax,4
mov ebx,1
mov ecx, msg3
mov edx, len3
int 80h
; moving the first number to eax register and second number to ebx
 ; and subtracting ascii '0' to convert it into a decimal number
 mov al, [var1]
 sub bl, '0'
 mov bl, [var2]
 sub bl, '0'
 ; subtract eax and ebx
 sub al, bl
 ; add '0' to to convert the sum from decimal to ASCII
 add al, '0'
 ; storing the sum in memory location res
 mov [res], al

mov eax,4 ;Prints equals sign
mov ebx,1
mov ecx, msg1
mov edx, len1
int 80h

mov eax,4 ;Prints answer
mov ebx,1
mov ecx, res
mov edx, 2
int 80h
jmp CheckOp


;Output: ;Output Statements




end:
mov eax,1
mov ebx,0
int 80h;