ShuriZma
/
stella
mirror of https://github.com/stella-emu/stella.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

ROMs smaller than 2K in the Cart2K class are now mirrored correctly, 

not by actually copying pieces of ROM, but by addressing different
parts of the ROM with an appropriate mask.  This fixes a patching
bug I just found, whereby patching one part of the ROM wasn't
propagating it to the rest of the image.


git-svn-id: svn://svn.code.sf.net/p/stella/code/trunk@1769 8b62c5a3-ac7e-4cc8-8f21-d9a121418aba
This commit is contained in:
stephena 2009-06-12 14:04:18 +00:00
parent 664d4e5d1a
commit 5d29bc0e2d
2 changed files with 28 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

39
src/emucore/Cart2K.cxx
View File

@ -28,25 +28,27 @@ Cartridge2K::Cartridge2K(const uInt8* image, uInt32 size)
// 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;
// Initialize ROM with illegal 6502 opcode that causes a real 6502 to jam
memset(myImage, 0x02, 2048);
myImage = new uInt8[mySize];
memset(myImage, 0x02, mySize);
// Mirror each power-of-two slice in the 2K address space
uInt32 slice = 1, numslices = 2048;
while(slice < size)
{
slice <<= 1;
numslices >>= 1;
}
// Copy the ROM image into my buffer
memcpy(myImage, image, size);
// Copy the ROM image slices into my buffer
for(uInt32 i = 0; i < numslices; ++i)
memcpy(myImage + i*slice, image, slice);
// Set mask for accessing the image buffer
// This is guaranteed to work, as mySize is a power of two
myMask = mySize - 1;
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Cartridge2K::~Cartridge2K()
{
delete[] myImage;
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@ -64,14 +66,13 @@ void Cartridge2K::install(System& system)
// Make sure the system we're being installed in has a page size that'll work
assert((0x1000 & mask) == 0);
System::PageAccess access;
access.directPokeBase = 0;
access.device = this;
// Map ROM image into the system
System::PageAccess access;
for(uInt32 address = 0x1000; address < 0x2000; address += (1 << shift))
{
access.directPeekBase = &myImage[address & 0x07FF];
access.device = this;
access.directPeekBase = &myImage[address & myMask];
access.directPokeBase = 0;
mySystem->setPageAccess(address >> shift, access);
}
}
@ -79,7 +80,7 @@ void Cartridge2K::install(System& system)
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
uInt8 Cartridge2K::peek(uInt16 address)
{
return myImage[address & 0x07FF];
return myImage[address & myMask];
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@ -110,14 +111,14 @@ int Cartridge2K::bankCount()
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
bool Cartridge2K::patch(uInt16 address, uInt8 value)
{
myImage[address & 0x07FF] = value;
myImage[address & myMask] = value;
return true;
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
uInt8* Cartridge2K::getImage(int& size)
{
size = 2048;
size = mySize;
return &myImage[0];
}

10
src/emucore/Cart2K.hxx
View File

@ -140,8 +140,14 @@ class Cartridge2K : public Cartridge
virtual void poke(uInt16 address, uInt8 value);
private:
// The 2k ROM image for the cartridge
uInt8 myImage[2048];
// Pointer to a dynamically allocated ROM image of the cartridge
uInt8* myImage;
// Size of the ROM image
uInt32 mySize;
// Mask to use for mirroring
uInt32 myMask;
};
#endif