Added samples for PL/0.

language/pl0/samples/fib.pas

@@ -0,0 +1,30 @@
+VAR i, x, r;
+
+PROCEDURE fib;
+VAR xx, r1, r2;
+BEGIN
+  xx := x;
+  IF xx = 0 THEN r := 1;
+  IF xx = 1 THEN r := 1;
+  IF xx >= 2 THEN BEGIN
+    x := xx - 2;
+    CALL fib;
+    r1 := r;
+
+    x := xx - 1;
+    CALL fib;
+    r2 := r;
+    r := r1 + r2;
+  END
+END;
+
+BEGIN
+  i := 0;
+  WHILE i < 30 DO BEGIN
+    x := i;
+    CALL fib;
+    write i;
+    write r;
+    i := i + 1;
+  END
+END.

language/pl0/samples/gcd.pas

@@ -0,0 +1,61 @@
+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;
+  write z;
+END.