code: /**
   * Copyright (c) 2005, Regents of the University of California
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * Redistributions of source code must retain the above copyright notice,
   * this list of conditions and the following disclaimer.
   *
   * Redistributions in binary form must reproduce the above copyright
   * notice, this list of conditions and the following disclaimer in the
   * documentation and/or other materials provided with the distribution.
   *
   * Neither the name of the University of California, Los Angeles nor the
   * names of its contributors may be used to endorse or promote products
   * derived from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *
   * Creation date: Sep 7, 2005
   */
  
  package avrora.arch.avr;
  
  import avrora.sim.*;
  import avrora.sim.clock.DeltaQueue;
  
  /**
   * The <code>AVRState</code> class represents an instance of the internal state of an <code>AVRInstrInterpreter</code>
   * instance. This class allows access to the state of the interpreter without exposing the details of the implementation
   * or jeopardizing the soundness of the simulation.
   * <p/>
   * </p> An <code>AVRState</code> instance contains the state of registers, memory, the code segment, and the IO
   * registers, as well as the interrupt table and <code>MainClock</code> instance. It provides a public interface through
   * the <code>get_XXX()</code> methods and a protected interface used in <code>AVRInstrInterpreter</code> that allows direct
   * access to the fields representing the actual state.
   *
   * @author Ben L. Titzer
   */
  public abstract class AVRState implements State {
  
      public static int NUM_REGS = 32;
  
      protected Simulator simulator;
  
      protected InterruptTable interrupts;
  
      protected int pc;
      protected int nextpc;
      protected boolean I, T, H, V, S, N, Z, C;
      protected AVRDataSegment sram;
      protected byte[] regs;
      protected CodeSegment flash;
      protected ActiveRegister[] ioregs;
      protected DeltaQueue queue;
      protected ActiveRegister SREG_reg;
      protected int SREG;
      protected int cycles;
      protected boolean justReturnedFromInterrupt;
  
      /**
       * The <code>getPC()</code> retrieves the current program counter.
       *
       * @return the program counter as a byte address
       */
      public int getPC() {
          return pc;
      }
  
      /**
       * The <code>getSP()</code> method reads the current value of the stack pointer. Since the stack pointer is stored
       * in two IO registers, this method will cause the invocation of the <code>.read()</code> method on each of the
       * <code>IOReg</code> objects that store these values.
       *
       * @return the value of the stack pointer as a byte address
       */
      public abstract int getSP();
  
      /**
       * The <code>getSRAM()</code> method reads a byte value from the data memory (SRAM) at the specified address. This
       * method is intended for use by probes and watches; thus, it does not trigger any watches that may be installed at
       * the memory address specified, since doing so could lead to infinite recursion (if a watch attempts to get the
       * value of the byte at the location where it itself is installed) or alter the metrics being measured by the
       * instrumentation at that address.
       *
       * @param address the byte address to read
       * @return the value of the data memory at the specified address
       * @throws ArrayIndexOutOfBoundsException if the specified address is not the valid memory range
       */
      public byte getSRAM(int address) {
          return sram.get(address);
      }
  
      /**
       * The <code>getFlash()</code> method reads a byte value from the program (Flash) memory. The flash memory generally
       * stores read-only values and the instructions of the program. This method is intended for use by probes and
       * watches; thus, it does not trigger any watches or probes that may be installed at the memory address specified,
       * since doing so could lead to infinite recursion (if a watch attempts to get the value of the byte at the location
       * where it itself is installed) or alter the metrics being measured by the instrumentation at that address.
       *
       * @param address the byte address at which to read
       * @return the byte value of the program memory at the specified address
       * @throws ArrayIndexOutOfBoundsException if the specified address is not the valid program memory range
       */
      public byte getFlash(int address) {
          return flash.get(address);
      }
  
      /**
       * The <code>getIOReg()</code> method reads the value of an IO register as a byte. Invocation of this method causes
       * an invocation of the <code>.read()</code> method on the corresponding internal <code>IOReg</code> object, and its
       * value returned. Very few devices have behavior that is triggered by a read from an IO register, but care should
       * be taken when calling this method for one of those IO registers.
       *
       * @param ior the IO register number
       * @return the value of the IO register
       */
      public byte getIOReg(int ior) {
          return ioregs[ior].read();
      }
  
      /**
       * The <code>getRegister()</code> method reads a general purpose register's current value as a byte.
       *
       * @param reg the register to read
       * @return the current value of the specified register as a byte
       */
      public byte getRegister(AVRSymbol.GPR reg) {
          return regs[reg.value];
      }
  
      /**
       * The <code>getCycles()</code> method returns the clock cycle count recorded so far in the simulation.
       *
       * @return the number of clock cycles elapsed in the simulation
       */
      public long getCycles() {
          return queue.getCount();
      }
  
      /**
       * The <code>getSREG()</code> method reads the value of the status register. The status register contains the I, T,
       * H, S, V, N, Z, and C flags, in order from highest-order to lowest-order.
       *
       * @return the value of the status register as a byte.
       */
      public byte getSREG() {
          return SREG_reg.read();
      }
  
      /**
       * The <code>isEnabled()</code> method checks whether the specified interrupt is currently enabled.
       *
       * @param inum the interrupt number to check
       * @return true if the specified interrupt is currently enabled; false otherwise
       */
      public boolean isEnabled(int inum) {
          return interrupts.isEnabled(inum);
      }
  
      /**
       * The <code>isPosted()</code> method checks whether the specified interrupt is currently posted.
       *
       * @param inum the interrupt number to check
       * @return true if the specified interrupt is currently posted; false otherwise
       */
      public boolean isPosted(int inum) {
          return interrupts.isPosted(inum);
      }
  
      /**
       * The <code>isPending()</code> method checks whether the specified interrupt is currently pending.
       *
       * @param inum the interrupt number to check
       * @return true if the specified interrupt is currently pending; false otherwise
       */
      public boolean isPending(int inum) {
          return interrupts.isPending(inum);
      }
  
      /**
       * The <code>getSimulator()</code> method returns the simulator associated with this state instance.
       *
       * @return a reference to the simulator associated with this state instance.
       */
      public Simulator getSimulator() {
          return simulator;
      }
  
      protected static int map_get(byte[] a, int indx) {
          return a[indx];
      }
  
      protected static void map_set(byte[] a, int indx, int val) {
          a[indx] = (byte)val;
      }
  
      protected static int map_get(Segment s, int addr) {
          return s.read(addr);
      }
  
      protected static void map_set(Segment s, int addr, int val) {
          s.write(addr, (byte)val);
      }
  
      protected static int map_get(ActiveRegister[] s, int addr) {
          return s[addr].read();
      }
  
      protected static void map_set(ActiveRegister[] s, int addr, int val) {
          s[addr].write((byte)val);
      }
  }
  