Move the Main instruction from register to virtual

also needs a branch in register.
This way the register level is self sufficient
(noticed while writing debugger)

lib/register/instruction.rb

@@ -43,4 +43,4 @@ require_relative "instructions/function_call"
 require_relative "instructions/function_return"
 require_relative "instructions/save_return"
 require_relative "instructions/register_transfer"
-require_relative "instructions/register_main"
+require_relative "instructions/branch"

lib/register/instructions/branch.rb

@@ -0,0 +1,12 @@
+module Register
+
+
+  # a branch must branch to a block.
+  class Branch < Instruction
+    def initialize to
+      raise "No block" unless to
+      @block = to
+    end
+    attr_reader :block
+  end
+end

lib/register/instructions/register_main.rb

@@ -1,19 +0,0 @@
-module Register
-
-  # This starts the register machine machine at the given function.
-
-  # The implementation is most likely a jump/branch , but since we have the extra layer
-  # we make good use of it, ie give things descriptive names (what they do, not how)
-
-  class RegisterMain < Instruction
-    include Positioned
-
-    def initialize method
-      @method = method
-    end
-    attr_reader :method
-    def word_length
-      4
-    end
-  end
-end

lib/register/passes/main_implementation.rb

@@ -0,0 +1,17 @@
+module Register
+
+  # "Boot" the virtual machine at the function given
+  # meaning jump to that function currently. Maybe better to do some machine setup
+  # and possibly some cleanup/exit has to tie in, but that is not this day
+
+  class MainImplementation
+    def run block
+      block.codes.dup.each do |code|
+        next unless code.is_a? Virtual::VirtualMain
+        branch = Register::Branch.new( code.method.source.blocks.first )
+        block.replace(code , branch )
+      end
+    end
+  end
+  Virtual.machine.add_pass "Register::MainImplementation"
+end

lib/register/register.rb

@@ -1,6 +1,7 @@
 require_relative "instruction"
 require_relative "register_reference"
 require_relative "assembler"
+require_relative "passes/main_implementation"
 require_relative "passes/frame_implementation"
 require_relative "passes/message_implementation"
 require_relative "passes/set_implementation"