gcd.pl

const
  m =  7,
  n = 85;
 
var
  x, y, z, q, r;
 
procedure multiply;
var a,b;
begin
  a := x;
  b := y;
  z := 0;
  while b > 0 do begin
    if odd b then z := z + a;
    a := 2 * a;
    b := b / 2
  end
end;
 
procedure divide;
var w;
begin
  r := x;
  q := 0;
  w := y;
  while w <= r do w := 2 * w;
  while w > y do begin
    q := 2 * q;
    w := w / 2;
    if w <= r then begin
      r := r - w;
      q := q + 1
    end
  end
end;
 
procedure gcd;
var f, g;
begin
  f := x;
  g := y;
  while f # g do begin
    if f < g then g := g - f;
    if g < f then f := f - g
  end;
  z := f
end;
 
begin
  x := m;
  y := n;
  call multiply;
  x := 25;
  y :=  3;
  call divide;
  x := 84;
  y := 36;
  call gcd
end.