stella/stella/src/emucore/CartF4SC.cxx

//============================================================================
//
//   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) 1995-1998 by Bradford W. Mott
//
// See the file "license" for information on usage and redistribution of
// this file, and for a DISCLAIMER OF ALL WARRANTIES.
//
// $Id: CartF4SC.cxx,v 1.1.1.1 2001-12-27 19:54:19 bwmott Exp $
//============================================================================

#include <assert.h>
#include "CartF4SC.hxx"
#include "Random.hxx"
#include "System.hxx"

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
CartridgeF4SC::CartridgeF4SC(const uInt8* image)
{
  // Copy the ROM image into my buffer
  for(uInt32 addr = 0; addr < 32768; ++addr)
  {
    myImage[addr] = image[addr];
  }

  // Initialize RAM with random values
  Random random;
  for(uInt32 i = 0; i < 128; ++i)
  {
    myRAM[i] = random.next();
  }
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
CartridgeF4SC::~CartridgeF4SC()
{
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
const char* CartridgeF4SC::name() const
{
  return "CartridgeF4SC";
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
void CartridgeF4SC::reset()
{
  // Upon reset we switch to bank 7
  bank(7);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
void CartridgeF4SC::install(System& system)
{
  mySystem = &system;
  uInt16 shift = mySystem->pageShift();
  uInt16 mask = mySystem->pageMask();

  // Make sure the system we're being installed in has a page size that'll work
  assert(((0x1080 & mask) == 0) && ((0x1100 & mask) == 0));

  // Set the page accessing methods for the hot spots
  System::PageAccess access;
  for(uInt32 i = (0x1FF4 & ~mask); i < 0x2000; i += (1 << shift))
  {
    access.directPeekBase = 0;
    access.directPokeBase = 0;
    access.device = this;
    mySystem->setPageAccess(i >> shift, access);
  }

  // Set the page accessing method for the RAM writing pages
  for(uInt32 j = 0x1000; j < 0x1080; j += (1 << shift))
  {
    access.device = this;
    access.directPeekBase = 0;
    access.directPokeBase = &myRAM[j & 0x007F];
    mySystem->setPageAccess(j >> shift, access);
  }

  // Set the page accessing method for the RAM reading pages
  for(uInt32 k = 0x1080; k < 0x1100; k += (1 << shift))
  {
    access.device = this;
    access.directPeekBase = &myRAM[k & 0x007F];
    access.directPokeBase = 0;
    mySystem->setPageAccess(k >> shift, access);
  }

  // Install pages for bank 7
  bank(7);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
uInt8 CartridgeF4SC::peek(uInt16 address)
{
  address = address & 0x0FFF;

  // Switch banks if necessary
  if((address >= 0x0FF4) && (address <= 0x0FFB))
  {
    bank(address - 0x0FF4);
  }

  // NOTE: This does not handle accessing RAM, however, this function 
  // should never be called for RAM because of the way page accessing 
  // has been setup
  return myImage[myCurrentBank * 4096 + address];
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
void CartridgeF4SC::poke(uInt16 address, uInt8)
{
  // Switch banks if necessary
  if((address >= 0x0FF4) && (address <= 0x0FFB))
  {
    bank(address - 0x0FF4);
  }

  // NOTE: This does not handle accessing RAM, however, this function 
  // should never be called for RAM because of the way page accessing 
  // has been setup
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
void CartridgeF4SC::bank(uInt16 bank)
{ 
  // Remember what bank we're in
  myCurrentBank = bank;
  uInt16 offset = myCurrentBank * 4096;
  uInt16 shift = mySystem->pageShift();
  uInt16 mask = mySystem->pageMask();

  // Setup the page access methods for the current bank
  System::PageAccess access;
  access.device = this;
  access.directPokeBase = 0;

  // Map ROM image into the system
  for(uInt32 address = 0x1100; address < (0x1FF4U & ~mask);
      address += (1 << shift))
  {
    access.directPeekBase = &myImage[offset + (address & 0x0FFF)];
    mySystem->setPageAccess(address >> shift, access);
  }
}