Add number of registers to platform

lib/risc/block_compiler.rb

@@ -1,7 +1,8 @@
 module Risc
 
   # A BlockCompiler is much like a MethodCompiler, exept for it's for blocks
-  # This only changes scoping for variables, lsee slot_type
+  # This only changes scoping for variables, see slot_type
+  # (dynamic resolve, as needed when the block is passed, is not implemented)
   #
   class BlockCompiler < CallableCompiler
 

lib/risc/callable_compiler.rb

@@ -25,6 +25,7 @@ module Risc
     end
     attr_reader :risc_instructions , :constants , :callable , :current
 
+    # find the return label. Every methd should have exactly one
     def return_label
       @risc_instructions.each do |ins|
         next unless ins.is_a?(Label)
@@ -33,6 +34,7 @@ module Risc
     end
 
     # add a constant (which get created during compilation and need to be linked)
+    # constants must be Parfait instances
     def add_constant(const)
       raise "Must be Parfait #{const}" unless const.is_a?(Parfait::Object)
       @constants << const

lib/risc/interpreter.rb

@@ -29,7 +29,7 @@ module Risc
       @registers = {}
       @flags = {  :zero => false , :plus => false ,
                   :minus => false , :overflow => false }
-      (0...12).each do |reg|
+      (0...InterpreterPlatform.new.num_registers).each do |reg|
         set_register "r#{reg}".to_sym , "r#{reg}:unknown"
       end
       @linker = linker

lib/risc/interpreter_platform.rb

@@ -10,6 +10,9 @@ module Risc
     def padding
       0x100 - loaded_at
     end
+    def num_registers
+      16
+    end
   end
   class Instruction
     def nil_next

lib/risc/platform.rb

@@ -13,6 +13,11 @@ module Risc
     # return an integer where the binary is loaded
     def loaded_at
     end
+
+    # return the number of registers the platform supports
+    def num_registers
+    end
+    
     # Factory method to create a Platform object according to the platform
     # string given.
     # Currently only "Arm" and "Interpreter"