add factorial example

Author: Carlos Rojas

examples/factorial/fac.wast

@@ -0,0 +1,42 @@
+(module
+ (import "env" "print_int"        (func $print       (type $i2v)))
+
+ (; Type declarations ;)
+ (type $i2v (func (param i32) (result)))
+ (type $i32toi32 (func (param i32) (result i32)))
+ (type $v2v (func (param) (result)))
+
+ (; Define one function ;)
+ (export "main" (func $main))
+ (memory 2)
+ (table funcref (elem $fac $dummy))
+
+ (global $g1  i32   (i32.const 0)) 
+ (global $g2 (mut i32) (i32.const 0))
+
+ (func $dummy (type $i2v))
+ (func $fac (type $i32toi32)
+     (i32.gt_s
+       (local.get 0)
+       (i32.const 1))
+     (if (result i32)
+       (then 
+         (i32.sub 
+           (local.get 0)
+           (i32.const 1))
+         (call $fac)
+         (local.get 0)
+         i32.mul)
+       (else
+          (i32.const 1))))
+
+ (func $main (type $v2v)
+    (local $arg i32)
+    (local.set $arg (i32.const 5))
+    (loop 
+       (local.get $arg)
+       (call $fac)
+       (call $print)
+       (br 0)))
+)
+