;; file: sub6.asm; Subprogram to C interfacing example; subroutine calc_sum; finds the sum of the integers 1 through n; Parameters:;   n    - what to sum up to (at [ebp + 8]); Return value:;   value of sum; pseudo C code:; int calc_sum( int n ); {;   int i, sum = 0;;   for( i=1; i <= n; i++ );     sum += i;;   return sum;; };; To assemble:; DJGPP:   nasm -f coff sub6.asm; Borland: nasm -f obj  sub6.asmsegment .text        global  calc_sum;; local variable:;   sum at [ebp-4]calc_sum:        enter   4,0               ; make room for sum on stack        mov     dword [ebp-4],0   ; sum = 0        mov     ecx, 1            ; ecx is i in pseudocodefor_loop:        cmp     ecx, [ebp+8]      ; cmp i and n        jnle    end_for           ; if not i <= n, quit        add     [ebp-4], ecx      ; sum += i        inc     ecx        jmp     short for_loopend_for:        mov     eax, [ebp-4]      ; eax = sum        leave        ret