title: x86 - Converting a string from stdin to integer to use elsewhere
body: <p>I am trying to make a program in x86 NASM that reads two integers from stdin and then does something with them (greatest common divisor, but thats not the question here).  The question I have, is now that I have the two input integers, how do I go about turning them into actual integers to use as such?  Here is the code I use to grab the strings of digits</p>
  
  <pre><code>SECTION .data
  
  prompt: db      "Enter a positive integer: "
  plen:   equ     $-prompt
  
  SECTION .bss
  
  inbuf:  resb 20
  inbuf2: resb 20
  
      SECTION .text
  
      global  _start
  
      _start:
  
         ; Here I am grabbing the two integers to use in the function
  
        nop
        mov       eax, 4          ; write
        mov       ebx, 1          ; to standard output
        mov       ecx, prompt     ; the prompt string
        mov       edx, plen       ; of length plen
        int   80H             ; interrupt with the syscall
  
        mov       eax, 3          ; read
        mov       ebx, 0          ; from standard input
        mov       ecx, inbuf      ; into the input buffer
        mov       edx, 30     ; upto 30 bytes
        int   80H             ; interrupt with the syscall
  
        mov       eax, 4          ; write
        mov       ebx, 1          ; to standard output
        mov       ecx, prompt     ; the prompt string
        mov       edx, plen       ; of length plen
        int   80H             ; interrupt with the syscall
  
        mov       eax, 3          ; read
        mov       ebx, 0          ; from standard input
        mov       ecx, inbuf2     ; into the input buffer
        mov       edx, 30     ; upto 30 bytes
        int   80H             ; interrupt with the syscall
  </code></pre>