Add functions

Author: dontru

src/functions.wat

@@ -0,0 +1,48 @@
+(module
+  (memory $memory 1)
+
+  ;; int si() {
+  ;;   static int x;
+  ;;   return ++x;
+  ;; }
+  (func $si (result i32)
+    (local $x i32)
+    (i32.store offset=12
+      (i32.const 0)
+      (tee_local $x
+        (i32.add
+          (i32.load offset=12
+            (i32.const 0))
+          (i32.const 1))))
+    (get_local $x))
+
+  ;; int factorial(int n) {
+  ;;   if (n == 0)
+  ;;     return 1;
+  ;;   else
+  ;;     return n * factorial(n - 1);
+  ;; }
+  (func $factorial (param $n i32) (result i32)
+    (local $l0 i32) (local $l1 i32)
+    (block $B0
+      (br_if $B0
+        (i32.eqz
+          (get_local $n)))
+      (set_local $l1
+        (i32.const 1))
+      (loop $L1
+        (set_local $l1
+          (i32.mul
+            (get_local $n)
+            (get_local $l1)))
+        (set_local $n
+          (tee_local $l0
+            (i32.add
+              (get_local $n)
+              (i32.const -1))))
+        (br_if $L1
+          (get_local $l0)))
+      (return
+        (get_local $l1)))
+    (i32.const 1))
+)