stella/src/emucore/CartDPCPlus.hxx

//============================================================================
//
//   SSSS    tt          lll  lll
//  SS  SS   tt           ll   ll
//  SS     tttttt  eeee   ll   ll   aaaa
//   SSSS    tt   ee  ee  ll   ll      aa
//      SS   tt   eeeeee  ll   ll   aaaaa  --  "An Atari 2600 VCS Emulator"
//  SS  SS   tt   ee      ll   ll  aa  aa
//   SSSS     ttt  eeeee llll llll  aaaaa
//
// Copyright (c) 1995-2010 by Bradford W. Mott, Stephen Anthony
// and the Stella Team
//
// See the file "License.txt" for information on usage and redistribution of
// this file, and for a DISCLAIMER OF ALL WARRANTIES.
//
// $Id$
//============================================================================

#ifndef CARTRIDGE_DPC_PLUS_HXX
#define CARTRIDGE_DPC_PLUS_HXX

class System;

#include "bspf.hxx"
#include "Cart.hxx"

/**
  Cartridge class used for DPC+.  There are six 4K program banks, a 4K
  display bank, 1K frequency table and the DPC chip.  For complete details on
  the DPC chip see David P. Crane's United States Patent Number 4,644,495.

  @author  Darrell Spice Jr, Fred Quimby, Stephen Anthony
  @version $Id$
*/
class CartridgeDPCPlus : public Cartridge
{
  public:
    /**
      Create a new cartridge using the specified image

      @param image Pointer to the ROM image
    */
    CartridgeDPCPlus(const uInt8* image, uInt32 size);
 
    /**
      Destructor
    */
    virtual ~CartridgeDPCPlus();

  public:
    /**
      Reset device to its power-on state
    */
    void reset();

    /**
      Notification method invoked by the system right before the
      system resets its cycle counter to zero.  It may be necessary
      to override this method for devices that remember cycle counts.
    */
    void systemCyclesReset();

    /**
      Install cartridge in the specified system.  Invoked by the system
      when the cartridge is attached to it.

      @param system The system the device should install itself in
    */
    void install(System& system);

    /**
      Install pages for the specified bank in the system.

      @param bank The bank that should be installed in the system
    */
    void bank(uInt16 bank);

    /**
      Get the current bank.
    */
    uInt16 bank() const;

    /**
      Query the number of banks supported by the cartridge.
    */
    uInt16 bankCount() const;

    /**
      Patch the cartridge ROM.

      @param address  The ROM address to patch
      @param value    The value to place into the address
      @return    Success or failure of the patch operation
    */
    bool patch(uInt16 address, uInt8 value);

    /**
      Access the internal ROM image for this cartridge.

      @param size  Set to the size of the internal ROM image data
      @return  A pointer to the internal ROM image data
    */
    const uInt8* getImage(int& size) const;

    /**
      Save the current state of this cart to the given Serializer.

      @param out  The Serializer object to use
      @return  False on any errors, else true
    */
    bool save(Serializer& out) const;

    /**
      Load the current state of this cart from the given Serializer.

      @param in  The Serializer object to use
      @return  False on any errors, else true
    */
    bool load(Serializer& in);

    /**
      Get a descriptor for the device name (used in error checking).

      @return The name of the object
    */
    string name() const { return "CartridgeDPCPlus"; }

  public:
    /**
      Get the byte at the specified address.

      @return The byte at the specified address
    */
    uInt8 peek(uInt16 address);

    /**
      Change the byte at the specified address to the given value

      @param address The address where the value should be stored
      @param value The value to be stored at the address
      @return  True if the poke changed the device address space, else false
    */
    bool poke(uInt16 address, uInt8 value);

  private:
    /** 
      Clocks the random number generator to move it to its next state
    */
    inline void clockRandomNumberGenerator();
  
    /** 
      Clocks the random number generator to move it to its prior state
    */
    inline void priorClockRandomNumberGenerator();

    /** 
      Updates any data fetchers in music mode based on the number of
      CPU cycles which have passed since the last update.
    */
    inline void updateMusicModeDataFetchers();

    /** 
      Call Special Functions
    */
    inline void callFunction(uInt8 value);

  private:
    // Indicates which bank is currently active
    uInt16 myCurrentBank;

    // The 24K program ROM image of the cartridge
    uInt8 myProgramImage[4096 * 6];

    // The 4K display ROM image of the cartridge
    uInt8 myDisplayImage[4096];

    // The 1K frequency table
    uInt8 myFrequencyImage[1024];
  
    // Copy of the raw image, for use by getImage()
    uInt8 myImageCopy[4096 * 6 + 4096 + 1024 + 255];

    // The top registers for the data fetchers
    uInt8 myTops[8];

    // The bottom registers for the data fetchers
    uInt8 myBottoms[8];

    // The counter registers for the data fetchers
    uInt16 myCounters[8];
  
    // The counter registers for the fractional data fetchers
    uInt32 myFractionalCounters[8];

    // The fractional increments for the data fetchers
    uInt8 myFractionalIncrements[8];

    // The flag registers for the data fetchers
    uInt8 myFlags[8];

    // The Fast Fetcher Enabled flag
    bool myFastFetch;
  
    // Flags that last byte peeked was A9 (LDA #)
    bool myLDAimmediate;

    // Parameter for special functions
    uInt8 myParameter;

    // The music mode counters
    uInt32 myMusicCounters[3];

    // The music frequency
    uInt32 myMusicFrequencies[3];
  
    // The music waveforms
    uInt16 myMusicWaveforms[3];
  
    // The random number generator register
    uInt32 myRandomNumber;

    // System cycle count when the last update to music data fetchers occurred
    Int32 mySystemCycles;

    // Fractional DPC music OSC clocks unused during the last update
    double myFractionalClocks;
};

#endif