stella/src/emucore/Cart2K.cxx

119 lines
3.3 KiB
C++

//============================================================================
//
// 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) 1995-2017 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.
//============================================================================
#include "System.hxx"
#include "Cart2K.hxx"
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Cartridge2K::Cartridge2K(const BytePtr& image, uInt32 size,
const Settings& settings)
: Cartridge(settings)
{
// Size can be a maximum of 2K
if(size > 2048) size = 2048;
// Set image size to closest power-of-two for the given size
mySize = 1;
while(mySize < size)
mySize <<= 1;
// We can't use a size smaller than the minimum page size in Stella
mySize = std::max(mySize, 1u << System::PAGE_SHIFT);
// Initialize ROM with illegal 6502 opcode that causes a real 6502 to jam
myImage = make_unique<uInt8[]>(mySize);
memset(myImage.get(), 0x02, mySize);
// Copy the ROM image into my buffer
memcpy(myImage.get(), image.get(), size);
createCodeAccessBase(mySize);
// Set mask for accessing the image buffer
// This is guaranteed to work, as mySize is a power of two
myMask = mySize - 1;
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
void Cartridge2K::reset()
{
myBankChanged = true;
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
void Cartridge2K::install(System& system)
{
mySystem = &system;
// Map ROM image into the system
// Note that we don't need our own peek/poke methods, since the mapping
// takes care of the entire address space
System::PageAccess access(this, System::PA_READ);
for(uInt32 address = 0x1000; address < 0x2000; address += (1 << System::PAGE_SHIFT))
{
access.directPeekBase = &myImage[address & myMask];
access.codeAccessBase = &myCodeAccessBase[address & myMask];
mySystem->setPageAccess(address >> System::PAGE_SHIFT, access);
}
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
bool Cartridge2K::patch(uInt16 address, uInt8 value)
{
myImage[address & myMask] = value;
return myBankChanged = true;
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
const uInt8* Cartridge2K::getImage(uInt32& size) const
{
size = mySize;
return myImage.get();
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
bool Cartridge2K::save(Serializer& out) const
{
try
{
out.putString(name());
}
catch(...)
{
cerr << "ERROR: Cartridge2K::save" << endl;
return false;
}
return true;
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
bool Cartridge2K::load(Serializer& in)
{
try
{
if(in.getString() != name())
return false;
}
catch(...)
{
cerr << "ERROR: Cartridge2K::load" << endl;
return false;
}
return true;
}