Implement BRANCH and 0BRANCH

wipforth.wat

@@ -625,6 +625,29 @@
 
        call $next)
 
+ ;; Branching
+
+ (func $branch
+	   global.get $ip
+	   i32.load
+	   global.get $ip
+	   i32.add
+	   global.set $ip
+	   call $next)
+
+ (func $zbranch
+	   call $pop
+	   if (result i32)
+	   global.get $ip
+	   i32.load
+	   else
+	   i32.const 4
+	   end
+	   global.get $ip
+	   i32.add
+	   global.set $ip
+	   call $next)
+
  ;; The codewords function table must contain every codeword we want
  ;; to be able to run, as it's indices into this table that can be ran
  ;; with call_indirect in the $trampoline loop.  Fantastically, there
@@ -955,6 +978,18 @@
        "\04EMIT\00\00\00"
        "\35\00\00\00")
 
+ (elem (i32.const 0x36) $branch)
+ (data (i32.const 0x0498)
+       "\88\04\00\00"
+       "\06BRANCH\00"
+       "\36\00\00\00")
+
+ (elem (i32.const 0x37) $branch)
+ (data (i32.const 0x04a8)
+       "\98\04\00\00"
+       "\070BRANCH"
+       "\37\00\00\00")
+
  ;; Built-in constants and variables
 
  ;; (data (i32.const 0x????)