.386 ;architecture
.model small,c ;pretty sure this lets you use __cdecl conventions
.data ;section for variables
	fmt db "Sum is %d",0 ;string declared
.code
	INCLUDELIB MSVCRT ;so you can link the vc functions
	EXTRN printf:NEAR ;namely, printf... 
	EXTRN exit:NEAR   ;and exit
PUBLIC main ;main function.. just like c
main: ;label 
	mov eax,5 ;put 5 in the eax register
	mov ebx,8 ;put 8 in the ebx register
	add eax,ebx ; add the contents of eax and ebx and put the result in eax
	push eax ; push eax onto the stack
	mov ebx, offset fmt ; put fmt in ebx
	push ebx ; push ebx onto the stack
	call printf ;call printf(fmt,13)
	nop ;delay slot
	mov eax,0 ;put 0 in eax
	push eax ; put eax on the stack
	call exit ; call exit(0)
	nop ; delay slot
END ; end directive

nasm -f coff sum.asm

int main()
{
  /*we call our calc() function*/

  calc();
return 0;
}

 gcc -o sum sum.o sum.c

;
; this segment contains initialised data
segment .data
fmt db "%s",0
msg db "Please enter a number: ",0
msgo db "The sum is %d",0
par db "%d",0

;code goes here
segment .text


	global _calc    ;declare our function calc(),as global 

 extern _printf,_scanf,_getch  ;declare prinf(),scanf()& getch() as external 

_calc:
	push ebp	;save the base pointer register on to the stack and
	mov ebp,esp ;make it equal to stack pointer as per cdecl conventions
	pusha		;save all general purpose registers on to the stack

	push msg ;push function parameters on to the stack in reverse order
	push fmt	; this is equal to ...
	call _printf      ;  printf("%s",msg) 

	lea ecx,[ebp-4] ;store into ecx the memory address of the first local variable inside
		;the calc() function ie.int calc(){ int x,y; } so on the stack x
			    ; is at [ebp-4]

	push ecx	;now ecx is a pointer to variable x at [ebp-4] so 
	push par ;we get a value from the keyboard and store it at x[ebp-4];
	call _scanf	;ie scanf("%d",&x); 

	push msg
	push fmt
	call _printf

	lea edx,[ebp-8] ;we load the address of the second variable i.e y into edx
 			 ;now edx is a pointer to y ie int calc(){int x; int y;}
      push edx	    ; int x; int* edx; edx =&y;  
	push par	    ; so *edx = 2 means y = 2
	call _scanf	    ;so again we scanf("%d",&y)

	mov ebx,dword[ebp-4] ;move the value inside our variable x into ebx 
	mov eax,dword[ebp-8] ;move the value of y into eax

	add eax,ebx		;addition, eax += ebx, eax = eax+ebx, y+=x;

	push eax
	push msgo		
	call _printf	;printf("The sum is %d",y);
      call _getch		;call the getch() function

      add esp,40		;we pushed 10 double words i.e sizeof(int)x10 onto the stack 
				; so we clean it up by adding 40 onto esp.a shortcut
	popa			;pop all general purpose registers from the stack
	mov esp,ebp		;restore the original value of esp
	pop ebp		;pop ebp out of the stack
	ret		;return to the caller function.

int calc();

int main()
{

    calc();
}

int calc()
{
   int x, y;
   printf("Please enter a number");
   scanf("%d",&x);
   printf("please enter a number");
   scanf("%d",&y);
   y+=x;
   printf("%d",y);
   return 0;
}

int __cdecl printf(const char * format, ...);
void __cdecl exit(int status);
#pragma comment(linker, "/NODEFAULTLIB")
#pragma comment(lib, "MSVCRT.LIB")
main()
{
const char *fmt = "Sum is %d";
int a, b;
a = 5;
b = 8;
a = a + b;
printf(fmt,a);
a = 0;
exit(a);
}