Title Find all factors (factors.asm)
; An assembly program calls external C/C++ functions.

INCLUDE Irvine32.inc

askForInteger PROTO C
showInt PROTO C, value:SDWORD, outWidth:DWORD

OUT_WIDTH = 8

.data
      save    DWORD ?
.code

;--------------------------------------------------------------
;  Inputs an integer n and displays all factors of the integer.
;--------------------------------------------------------------

DisplayFactors PROC C
    INVOKE askForInteger                  ; call C++ function
    mov    save, eax
    cmp    eax, 0    mov    ecx, eax
L1: mov    eax, save                      ; EAX = input
    cdq                                   ; dividend = EDX:EAX
    idiv   ecx                            ; divisor  = ECX
    .IF ( edx == 0 )                      ; remainder == 0
      push   ecx                          ; save ECX
      INVOKE showInt, ecx, OUT_WIDTH      ; call C++ function
      call   Crlf
      pop    ecx                          ; restore ECX
    .ENDIF
    loop   L1
L2: ret
DisplayFactors ENDP

END

// main.cpp

// Demonstrates function calls between a C++ program
// and an external assembly language module.

#include  <iostream>
#include  <iomanip>
using namespace  std;


extern "C" {
  // external ASM procedures:
  void  DisplayFactors( );

  // local C++ functions:
  int   askForInteger( );
  void  showInt( int value, int width );
}


// program entry point
int  main( ) {
  DisplayFactors( );                    // call ASM procedure
  return( 0 );
}


// Prompt the user for an integer. 
int  askForInteger( ) {
  int  n;
  cout << "Enter a positive integer: ";
  cin  >> n;
  return( n );
}


// Display a signed integer with a specified width.
void  showInt( int value, int width ) {
  cout << setw( width ) << value;
}