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Adjusted bank() and bankCount() functions according to advice from SA. 

removed 'myCurrentBank' -- this has no meaning in this scheme.
Adjusted load() to switch in each bank as it is loaded
removed comment/questions to SA and replaced per advice.
added a few TODO comments.
reformatted some of the comments back, as per discussion

git-svn-id: svn://svn.code.sf.net/p/stella/code/trunk@2902 8b62c5a3-ac7e-4cc8-8f21-d9a121418aba
This commit is contained in:
adavie 2014-06-03 21:17:54 +00:00
parent cacecbeddd
commit abdd770e38
2 changed files with 25 additions and 53 deletions
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77
src/emucore/CartDASH.cxx
View File

@ -32,20 +32,16 @@ CartridgeDASH::CartridgeDASH(const uInt8* image, uInt32 size, const Settings& se
// Copy the ROM image into my buffer
memcpy(myImage, image, mySize);
createCodeAccessBase(mySize + RAM_TOTAL_SIZE);
createCodeAccessBase(mySize + RAM_TOTAL_SIZE); // TODO: how does the RAM write offset affect the size we need?
// This cart can address 4 banks of RAM, each 512 bytes @ 1000, 1200, 1400, 1600
// However, it may not be addressable all the time (it may be swapped out)
// TODO: Stephen -- is this correct for defining 4 separate RAM areas, or can it be done as one block?
registerRamArea(0x1000, RAM_BANK_SIZE, 0x00, RAM_WRITE_OFFSET); // 512 bytes RAM @ 0x1000
registerRamArea(0x1200, RAM_BANK_SIZE, 0x00, RAM_WRITE_OFFSET); // 512 bytes RAM @ 0x1200
registerRamArea(0x1400, RAM_BANK_SIZE, 0x00, RAM_WRITE_OFFSET); // 512 bytes RAM @ 0x1400
registerRamArea(0x1600, RAM_BANK_SIZE, 0x00, RAM_WRITE_OFFSET); // 512 bytes RAM @ 0x1600
myCurrentBank = -1; // nothing switched
// Remember startup bank (0 per spec, rather than last per 3E scheme).
// Set this to go to 3rd 1K Bank.
myStartBank = (3 << BANK_BITS) | 0;
@ -98,7 +94,7 @@ void CartridgeDASH::install(System& system) {
access.codeAccessBase = &myCodeAccessBase[byte];
mySystem->setPageAccess(address >> shift, access);
// TODO: Stephen: in this and other implementations we appear to be using "shift" as a system-dependant mangle for
// TODO: In this and other implementations we appear to be using "shift" as a system-dependant mangle for
// different access types (byte/int/32bit) on different architectures. I think I understand that much. However,
// I have an issue with how these loops are encoded in all the bank schemes I've seen. The issue being that
// the loop inits set some address (e.g., 0x1800) and then add a shifted value to it every loop. But when
@ -124,9 +120,6 @@ uInt8 CartridgeDASH::peek(uInt16 address) {
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
assert(false);
value = mySystem->randGenerator().next();
} else if (imageBank & BITMASK_ROMRAM) { // a RAM bank
@ -166,8 +159,9 @@ bool CartridgeDASH::poke(uInt16 address, uInt8 value) {
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
bool CartridgeDASH::bank(uInt16 bank) {
if (bankLocked())
return false; // TODO: Stephen -- ? no idea
return false; // debugger has locked the bank
uInt16 shift = mySystem->pageShift();
@ -176,12 +170,9 @@ bool CartridgeDASH::bank(uInt16 bank) {
if (bank & BITMASK_ROMRAM) { // switching to a 512 byte RAM bank
// Wrap around/restrict to valid range
uInt16 currentBank = bank & BIT_BANK_MASK;
// Record which bank switched in (marked as RAM)
myCurrentBank = bankInUse[bankNumber] = (Int16) (BITMASK_ROMRAM | currentBank);
// Effectively * 512 bytes
uInt32 startCurrentBank = currentBank << RAM_BANK_TO_POWER;
uInt16 currentBank = bank & BIT_BANK_MASK; // Wrap around/restrict to valid range
bankInUse[bankNumber] = (Int16) (BITMASK_ROMRAM | currentBank); // Record which bank switched in (marked as RAM)
uInt32 startCurrentBank = currentBank << RAM_BANK_TO_POWER; // Effectively * 512 bytes
// Setup the page access methods for the current bank
System::PageAccess access(0, 0, 0, this, System::PA_READ);
@ -189,10 +180,7 @@ bool CartridgeDASH::bank(uInt16 bank) {
// Map read-port RAM image into the system
for (uInt32 byte = 0; byte < RAM_BANK_SIZE; byte += (1 << shift)) {
access.directPeekBase = &myRAM[startCurrentBank + byte];
// TODO: Stephen please explain/review the use of mySize as an offset for RAM access here....
access.codeAccessBase = &myCodeAccessBase[mySize + startCurrentBank + byte]; //?eh
access.codeAccessBase = &myCodeAccessBase[mySize + startCurrentBank + byte];
mySystem->setPageAccess((startCurrentBank + byte) >> shift, access);
}
@ -210,10 +198,8 @@ bool CartridgeDASH::bank(uInt16 bank) {
// Map ROM bank image into the system into the correct slot
// Memory map is 1K slots at 0x1000, 0x1400, 0x1800, 0x1C00
// Record which bank switched in (as ROM)
myCurrentBank = bankInUse[bankNumber] = (Int16) bankID;
// Effectively *1K
uInt32 startCurrentBank = bankID << ROM_BANK_TO_POWER;
bankInUse[bankNumber] = (Int16) bankID; // Record which bank switched in (as ROM)
uInt32 startCurrentBank = bankID << ROM_BANK_TO_POWER; // Effectively *1K
// Setup the page access methods for the current bank
System::PageAccess access(0, 0, 0, this, System::PA_READ);
@ -232,40 +218,32 @@ bool CartridgeDASH::bank(uInt16 bank) {
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
uInt16 CartridgeDASH::bank() const {
// TODO: Stephen -- what to do here? We don't really HAVE a "current bank"; we have 4 banks
// and they are defined in bankInUse[...].
// What I've done is kept track of the last switched bank, and return that. But that doesn't tell us WHERE. :(
return myCurrentBank;
// Doesn't support bankswitching in the normal sense
return 0;
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
uInt16 CartridgeDASH::bankCount() const {
// We have a constant # banks for this scheme; 32 ROM and 32 RAM (or, at least, RAM_BANK_COUNT and ROM_BANK_COUNT)
// See usage of bank bits.
// TODO: Stephen -- What should this return, given the mangled bank value?
return ROM_BANK_COUNT + RAM_BANK_COUNT;
// Doesn't support bankswitching in the normal sense
// There is are 4 'virtual' ROM banks that can change in many different ways, and 4 virtual RAM banks...
return 8;
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
bool CartridgeDASH::patch(uInt16 address, uInt8 value) {
// Patch the cartridge ROM
// TODO: Stephen... I assume this is for some sort of debugger support....?
// Patch the cartridge ROM (for debugger)
myBankChanged = true;
uInt32 bankNumber = (address >> ROM_BANK_TO_POWER) & 3; // now 1K bank # (ie: 0-3)
Int32 whichBankIsThere = bankInUse[bankNumber]; // ROM or RAM bank reference
uInt32 bankNumber = (address >> ROM_BANK_TO_POWER) & 3; // now 1K bank # (ie: 0-3)
Int32 whichBankIsThere = bankInUse[bankNumber]; // ROM or RAM bank reference
if (whichBankIsThere == BANK_UNDEFINED) {
// We're trying to access undefined memory (no bank here yet)
// TODO: Stephen -- what to do here? Fail silently?
// want to throw some sort of Stella error -- trying to patch an unswitched in bank!
assert(false);
// We're trying to access undefined memory (no bank here yet). Fail!
myBankChanged = false;
} else if (whichBankIsThere & BITMASK_ROMRAM) { // patching RAM (512 byte banks)
@ -294,9 +272,8 @@ const uInt8* CartridgeDASH::getImage(int& size) const {
bool CartridgeDASH::save(Serializer& out) const {
try {
out.putString(name());
out.putShort(myCurrentBank);
for (uInt32 bank = 0; bank < 4; bank++)
out.putShort(bankInUse[bank]);
for (uInt32 b = 0; b < 4; b++)
out.putShort(bankInUse[b]);
out.putByteArray(myRAM, RAM_TOTAL_SIZE);
} catch (...) {
cerr << "ERROR: CartridgeDASH::save" << endl;
@ -314,17 +291,13 @@ bool CartridgeDASH::load(Serializer& in) {
try {
if (in.getString() != name())
return false;
myCurrentBank = in.getShort();
for (uInt32 bank = 0; bank < 4; bank++)
bankInUse[bank] = in.getShort();
for (uInt32 b = 0; b < 4; b++) {
bank(bankInUse[b] = in.getShort()); // read, and switch it in
}
in.getByteArray(myRAM, RAM_TOTAL_SIZE);
} catch (...) {
cerr << "ERROR: CartridgeDASH::load" << endl;
return false;
}
// Now, go to the current bank
bank(myCurrentBank);
return true;
}

1
src/emucore/CartDASH.hxx
View File

@ -244,7 +244,6 @@ public:
bool poke(uInt16 address, uInt8 value);
private:
Int16 myCurrentBank; // whatever the LAST switched bank was...
uInt32 mySize; // Size of the ROM image
uInt8* myImage; // Pointer to a dynamically allocated ROM image of the cartridge