- Add a skeleton MIPS assembler, disassembler and simulator.

runtime/vm/simulator_mips.h

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // Declares a Simulator for MIPS instructions if we are not generating a native
 // MIPS binary. This Simulator allows us to run and debug MIPS code generation
 // on regular desktop machines.
 // Dart calls into generated code by "calling" the InvokeDartCode stub,
 // which will start execution in the Simulator or forwards to the real entry
 // on a MIPS HW platform.
@@ skipping 30 matching lines @@
   // Call on program start.
   static void InitOnce();
 
   // Dart generally calls into generated code with 5 parameters. This is a
   // convenience function, which sets up the simulator state and grabs the
   // result on return.
   int64_t Call(int32_t entry,
                int32_t parameter0,
                int32_t parameter1,
                int32_t parameter2,
-               int32_t parameter3,
-               int32_t parameter4);
+               int32_t parameter3);
 
  private:
+  // A pc value used to signal the simulator to stop execution.  Generally
+  // the ra is set to this value on transition from native C code to
+  // simulated execution, so that the simulator can "return" to the native
+  // C code.
+  static const uword kEndSimulatingPC = -1;
+
+  int32_t registers_[kNumberOfCpuRegisters];
+  uword pc_;
+
+  // Simulator support.
   char* stack_;
+  int icount_;
+  bool delay_slot_;
+
+  void set_pc(uword value) { pc_ = value; }
+
+  void Format(Instr* instr, const char* format);
+
+  void DecodeSpecial(Instr* instr);
+  void InstructionDecode(Instr* instr);
+
+  void Execute();
+  void ExecuteDelaySlot();
 };
 
 }  // namespace dart
 
 #endif  // VM_SIMULATOR_MIPS_H_