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//============================================================================
//
// 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) 1995-2007 by Bradford W. Mott and the Stella team
//
// See the file "license" for information on usage and redistribution of
// this file, and for a DISCLAIMER OF ALL WARRANTIES.
//
// $Id: Cart3E.hxx,v 1.5 2007/01/14 16:17:52 stephena Exp $
//============================================================================
#ifndef CARTRIDGE3E_HXX
#define CARTRIDGE3E_HXX
class System;
class Serializer;
class Deserializer;
#include "m6502/src/bspf/src/bspf.hxx"
#include "Cart.hxx"
#include "Random.hxx"
/**
This is the cartridge class for Tigervision's bankswitched
games with RAM (basically, 3F plus up to 32K of RAM). This
code is basically Brad's Cart3F code plus 32K RAM support.
In this bankswitching scheme the 2600's 4K cartridge
address space is broken into two 2K segments. The last 2K
segment always points to the last 2K of the ROM image.
The lower 2K of address space maps to either one of the 2K ROM banks
(up to 256 of them, though only 240 are supposed to be used for
compatibility with the Kroko Cart and Cuttle Cart 2), or else one
of the 1K RAM banks (up to 32 of them). Like other carts with RAM,
this takes up twice the address space that it should: The lower 1K
is the read port, and the upper 1K is the write port (maps to the
same memory).
To map ROM, the desired bank number of the first 2K segment is selected
by storing its value into $3F. To map RAM in the first 2K segment
instead, store the RAM bank number into $3E.
This implementation of 3E bankswitching numbers the ROM banks 0 to
256, and the RAM banks 256 to 287. This is done because the public
bankswitching interface requires us to use one bank number, not one
bank number plus the knowledge of whether it's RAM or ROM.
All 32K of potential RAM is available to a game using this class, even
though real cartridges might not have the full 32K: We have no way to
tell how much RAM the game expects. This may change in the future (we
may add a stella.pro property for this), but for now it shouldn't cause
any problems. (Famous last words...)
@author B. Watson
@version $Id: Cart3E.hxx,v 1.5 2007/01/14 16:17:52 stephena Exp $
*/
class Cartridge3E : public Cartridge
{
public:
/**
Create a new cartridge using the specified image and size
@param image Pointer to the ROM image
@param size The size of the ROM image
@param rng A random number generator used to populate the initial extra RAM
*/
Cartridge3E(const uInt8* image, uInt32 size, Random& rng);
/**
Destructor
*/
virtual ~Cartridge3E();
public:
/**
Get a null terminated string which is the device's name (i.e. "M6532")
@return The name of the device
*/
virtual const char* name() const;
/**
Reset device to its power-on state
*/
virtual void reset();
/**
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
*/
virtual void install(System& system);
/**
Saves the current state of this device to the given Serializer.
@param out The serializer device to save to.
@return The result of the save. True on success, false on failure.
*/
virtual bool save(Serializer& out);
/**
Loads the current state of this device from the given Deserializer.
@param in The deserializer device to load from.
@return The result of the load. True on success, false on failure.
*/
virtual bool load(Deserializer& in);
/**
Install pages for the specified bank in the system.
@param bank The bank that should be installed in the system
*/
virtual void bank(uInt16 bank);
/**
Get the current bank.
@return The current bank, or -1 if bankswitching not supported
*/
virtual int bank();
/**
Query the number of banks supported by the cartridge.
*/
virtual int bankCount();
/**
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
*/
virtual 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
*/
virtual uInt8* getImage(int& size);
public:
/**
Get the byte at the specified address
@return The byte at the specified address
*/
virtual 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
*/
virtual void poke(uInt16 address, uInt8 value);
private:
// Indicates which bank is currently active for the first segment
uInt16 myCurrentBank;
// Pointer to a dynamically allocated ROM image of the cartridge
uInt8* myImage;
// RAM contents. For now every ROM gets all 32K of potential RAM
uInt8 myRam[32768];
// Size of the ROM image
uInt32 mySize;
};
#endif