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modified poke to handle the new bank encoding (a single byte, with the RAM/ROM bit encoded). 

git-svn-id: svn://svn.code.sf.net/p/stella/code/trunk@2899 8b62c5a3-ac7e-4cc8-8f21-d9a121418aba
This commit is contained in:
adavie 2014-06-03 13:04:35 +00:00
parent d4bed6da4b
commit 6d6dd7632f
1 changed files with 11 additions and 14 deletions
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25
src/emucore/CartDASH.cxx
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@ -123,10 +123,10 @@ void CartridgeDASH::install(System& system)
uInt8 CartridgeDASH::peek(uInt16 address)
{
uInt8 value = 0;
uInt32 bank = (address >> 10) & 3; // convert to 1K bank index (0-3)
Int16 imageBank = bankInUse[bank]; // the ROM/RAM bank that's here
uInt32 bank = (address >> ROM_BANK_TO_POWER) & 3; // convert to 1K bank index (0-3)
Int16 imageBank = bankInUse[bank]; // the ROM/RAM bank that's here
if(imageBank <= BANK_UNDEFINED)
if(imageBank == BANK_UNDEFINED) // an uninitialised bank?
{
// accessing invalid bank, so return should be... random?
// TODO: Stephen -- throw some sort of error; looking at undefined data
@ -134,22 +134,19 @@ uInt8 CartridgeDASH::peek(uInt16 address)
assert(false);
value = mySystem->randGenerator().next();
}
else if(imageBank < ROM_BANK_COUNT) // accessing ROM
else if (imageBank & ROMRAM) // a RAM bank
{
Int32 ramBank = imageBank & BIT_BANK_MASK; // discard irrelevant bits
Int32 offset = ramBank << RAM_BANK_TO_POWER; // base bank address in RAM
offset += (address & (RAM_BANK_SIZE-1)); // + byte offset in RAM bank
value = myRAM[offset];
}
else // accessing ROM
{
Int32 offset = imageBank << ROM_BANK_TO_POWER; // base bank address in image
offset += (address & (ROM_BANK_SIZE-1)); // + byte offset in image bank
value = myImage[offset];
}
else // must be a RAM bank
{
Int32 ramBank = imageBank - ROM_BANK_COUNT;
assert(ramBank < RAM_BANK_COUNT); // would be bad, otherwise
Int32 offset = ramBank << RAM_BANK_TO_POWER; // base bank address in RAM
offset += (address & (RAM_BANK_SIZE-1)); // + byte offset in RAM bank
value = myRAM[offset];
}
return value;
}