-- Code of Figure 1.8, page 26 from
-- Kenneth C. Louden, Programming Languages
-- Principles and Practice 2nd Edition
-- Copyright (C) Brooks-Cole/ITP, 2003
-- Note: I have also added (but not used)
-- the code from Figures 1.1 (p. 11)
-- and 1.2 (p. 12)

with Text_IO; use Text_IO;
with Ada.Integer_Text_IO;
use Ada.Integer_Text_IO;

procedure gcd_prog is

  function gcd (u, v: in integer) return integer is
  begin
    if v = 0 then
      return u;
    else
      return gcd(v, u mod v);
    end if;
  end gcd;

-- code from Figure 1.1, p. 11
  procedure gcd (u, v: in integer; x: out integer) is
    y, t, z: integer;
  begin
    z := u;
    y := v;
    loop
      exit when y = 0;
      t := y;
      y := z mod y;
      z := t;
    end loop;
    x := z;
  end gcd;

-- code from Figure 1.2, p. 12 (renamed to avoid name clash)
  function gcd2 (u, v: in integer) return integer is
    y, t, z: integer;
  begin
    z := u;
    y := v;
    loop
      exit when y = 0;
      t := y;
      y := z mod y;
      z := t;
    end loop;
    return z;
  end gcd2;

  x: Integer;
  y: Integer;

begin
  put_line("Input two integers:");
  get(x);
  get(y);
  put("The gcd of ");
  put(x);
  put(" and ");
  put(y);
  put(" is ");
  put(gcd(x,y));
  new_line;
end gcd_prog;