mirror of https://github.com/stella-emu/stella.git
Refactoring, properly model bus activity.
This commit is contained in:
Christian Speckner
parent
fe6e67de32
commit
4e6d009435
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@ -315,6 +315,12 @@ class Cartridge : public Device
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*/
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virtual uInt32 thumbCallback(uInt8 function, uInt32 value1, uInt32 value2) { return 0; }
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virtual uInt8 overdrivePeek(uInt16 address, uInt8 value) { return value; }
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virtual uInt8 overdrivePoke(uInt16 address, uInt8 value) { return value; }
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virtual bool doesBusStuffing() { return false; }
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#ifdef DEBUGGER_SUPPORT
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/**
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Get optional debugger widget responsible for displaying info about the cart.
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@ -23,7 +23,7 @@
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#include "CartELF.hxx"
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namespace {
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constexpr size_t READ_STREAM_CAPACITY = 1024;
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constexpr size_t TRANSACTION_QUEUE_CAPACITY = 16384;
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constexpr uInt8 OVERBLANK_PROGRAM[] = {
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0xa0,0x00, // ldy #0
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@ -82,11 +82,13 @@ CartridgeELF::~CartridgeELF() {}
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void CartridgeELF::reset()
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{
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std::fill_n(myLastPeekResult.get(), 0x1000, 0);
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myIsBusDriven = false;
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myDriveBusValue = 0;
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myReadStream.reset();
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myReadStream.push(0x00, 0x0ffc);
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myReadStream.push(0x10);
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myReadStream.setNextPushAddress(0);
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myTransactionQueue.reset();
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myTransactionQueue.injectROM(0x00, 0x1ffc);
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myTransactionQueue.injectROM(0x10);
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myTransactionQueue.setNextPushAddress(0x1000);
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vcsCopyOverblankToRiotRam();
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vcsStartOverblank();
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@ -121,10 +123,8 @@ bool CartridgeELF::load(Serializer& in)
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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uInt8 CartridgeELF::peek(uInt16 address)
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{
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if (myReadStream.isYield()) return mySystem->getDataBusState();
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myLastPeekResult[address & 0xfff] = myReadStream.pop(address);
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return myLastPeekResult[address & 0xfff];
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// The actual handling happens in overdrivePeek
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return 0;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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@ -146,14 +146,41 @@ const ByteBuffer& CartridgeELF::getImage(size_t& size) const
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return myImage;
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}
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uInt8 CartridgeELF::overdrivePeek(uInt16 address, uInt8 value)
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{
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value = driveBus(address, value);
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if (address & 0x1000) {
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if (!myIsBusDriven) value = mySystem->getDataBusState();
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myLastPeekResult[address & 0xfff] = value;
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}
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return value;
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}
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uInt8 CartridgeELF::overdrivePoke(uInt16 address, uInt8 value)
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{
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return driveBus(address, value);
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}
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inline uInt8 CartridgeELF::driveBus(uInt16 address, uInt8 value)
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{
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BusTransaction* nextTransaction = myTransactionQueue.getNextTransaction(address);
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if (nextTransaction) nextTransaction->setBusState(myIsBusDriven, myDriveBusValue);
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if (myIsBusDriven) value |= myDriveBusValue;
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return value;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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void CartridgeELF::vcsWrite5(uInt8 zpAddress, uInt8 value)
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{
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myReadStream.push(0xa9);
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myReadStream.push(value);
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myReadStream.push(0x85);
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myReadStream.push(zpAddress);
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myReadStream.yield();
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myTransactionQueue.injectROM(0xa9);
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myTransactionQueue.injectROM(value);
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myTransactionQueue.injectROM(0x85);
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myTransactionQueue.injectROM(zpAddress);
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myTransactionQueue.yield(zpAddress);
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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@ -165,101 +192,111 @@ void CartridgeELF::vcsCopyOverblankToRiotRam()
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void CartridgeELF::vcsStartOverblank()
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{
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myReadStream.push(0x4c);
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myReadStream.push(0x80);
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myReadStream.push(0x00);
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myReadStream.yield();
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myTransactionQueue.injectROM(0x4c);
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myTransactionQueue.injectROM(0x80);
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myTransactionQueue.injectROM(0x00);
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myTransactionQueue.yield(0x0080);
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}
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CartridgeELF::BusTransaction CartridgeELF::BusTransaction::transactionYield(uInt16 address)
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{
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address &= 0x1fff;
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return {.address = address, .value = 0, .yield = true};
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}
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CartridgeELF::BusTransaction CartridgeELF::BusTransaction::transactionDrive(uInt16 address, uInt8 value)
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{
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address &= 0x1fff;
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return {.address = address, .value = value, .yield = false};
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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void CartridgeELF::BusTransaction::setBusState(bool& drive, uInt8& value)
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{
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if (yield) {
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drive = false;
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} else {
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drive = true;
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value = this->value;
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}
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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CartridgeELF::ReadStream::ReadStream()
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CartridgeELF::BusTransactionQueue::BusTransactionQueue()
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{
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myStream = make_unique<ScheduledRead[]>(READ_STREAM_CAPACITY);
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myQueue = make_unique<BusTransaction[]>(TRANSACTION_QUEUE_CAPACITY);
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reset();
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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void CartridgeELF::ReadStream::reset()
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void CartridgeELF::BusTransactionQueue::reset()
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{
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myStreamNext = myStreamSize = myNextPushAddress = 0;
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myIsYield = true;
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myQueueNext = myQueueSize = 0;
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myNextInjectAddress = 0;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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void CartridgeELF::ReadStream::setNextPushAddress(uInt16 address)
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void CartridgeELF::BusTransactionQueue::setNextPushAddress(uInt16 address)
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{
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myNextPushAddress = address;
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myNextInjectAddress = address;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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void CartridgeELF::ReadStream::push(uInt8 value)
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void CartridgeELF::BusTransactionQueue::injectROM(uInt8 value)
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{
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if (myNextPushAddress > 0xfff)
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throw FatalEmulationError("read stream pointer overflow");
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push(value, myNextPushAddress);
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injectROM(value, myNextInjectAddress);
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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void CartridgeELF::ReadStream::push(uInt8 value, uInt16 address)
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void CartridgeELF::BusTransactionQueue::injectROM(uInt8 value, uInt16 address)
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{
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if (myStreamSize == READ_STREAM_CAPACITY)
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push(BusTransaction::transactionDrive(address, value));
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myNextInjectAddress = address + 1;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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void CartridgeELF::BusTransactionQueue::yield(uInt16 address)
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{
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push(BusTransaction::transactionYield(address));
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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bool CartridgeELF::BusTransactionQueue::hasPendingTransaction() const
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{
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return myQueueSize > 0;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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CartridgeELF::BusTransaction* CartridgeELF::BusTransactionQueue::getNextTransaction(uInt16 address)
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{
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if (myQueueSize == 0) return nullptr;
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BusTransaction* nextTransaction = &myQueue[myQueueNext];
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if (nextTransaction->address != (address & 0x1fff)) return nullptr;
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myQueueNext = (myQueueNext + 1) % TRANSACTION_QUEUE_CAPACITY;
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myQueueSize--;
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return nextTransaction;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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void CartridgeELF::BusTransactionQueue::push(const BusTransaction& transaction)
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{
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if (myQueueSize > 0) {
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BusTransaction& lastTransaction = myQueue[(myQueueNext + myQueueSize - 1) % TRANSACTION_QUEUE_CAPACITY];
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if (lastTransaction.address == transaction.address) {
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lastTransaction = transaction;
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return;
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}
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}
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if (myQueueSize == TRANSACTION_QUEUE_CAPACITY)
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throw FatalEmulationError("read stream overflow");
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address &= 0xfff;
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myStream[(myStreamNext + myStreamSize++) % READ_STREAM_CAPACITY] =
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{.address = address, .value = value, .yield = false};
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myNextPushAddress = address + 1;
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myIsYield = false;
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myQueue[(myQueueNext + myQueueSize++) % TRANSACTION_QUEUE_CAPACITY] = transaction;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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void CartridgeELF::ReadStream::yield()
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{
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if (myStreamSize == 0)
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throw new FatalEmulationError("yield called on empty stream");
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myStream[(myStreamNext + myStreamSize - 1) % READ_STREAM_CAPACITY].yield = true;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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bool CartridgeELF::ReadStream::isYield() const
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{
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return myIsYield;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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bool CartridgeELF::ReadStream::hasPendingRead() const
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{
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return myStreamSize > 0;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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uInt8 CartridgeELF::ReadStream::pop(uInt16 readAddress)
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{
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if (myStreamSize == 0) {
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ostringstream s;
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s << "read stream underflow at 0x" << std::hex << std::setw(4) << readAddress;
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throw FatalEmulationError(s.str());
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}
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if ((readAddress & 0xfff) != myStream[myStreamNext].address)
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{
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ostringstream s;
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s <<
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"unexcpected cartridge read from 0x" << std::hex << std::setw(4) <<
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std::setfill('0') << (readAddress & 0xfff) << " expected 0x" << myStream[myStreamNext].address;
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throw FatalEmulationError(s.str());
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}
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myIsYield = myStream[myStreamNext].yield && myStreamSize == 1;
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const uInt8 value = myStream[myStreamNext++].value;
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myStreamNext %= READ_STREAM_CAPACITY;
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myStreamSize--;
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return value;
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}
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@ -52,42 +52,56 @@ class CartridgeELF: public Cartridge {
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string name() const override { return "CartridgeELF"; };
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uInt8 overdrivePeek(uInt16 address, uInt8 value) override;
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uInt8 overdrivePoke(uInt16 address, uInt8 value) override;
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bool doesBusStuffing() override { return true; }
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private:
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uInt8 driveBus(uInt16 address, uInt8 value);
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void vcsWrite5(uInt8 zpAddress, uInt8 value);
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void vcsCopyOverblankToRiotRam();
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void vcsStartOverblank();
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private:
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struct ScheduledRead {
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struct BusTransaction {
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static BusTransaction transactionYield(uInt16 address);
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static BusTransaction transactionDrive(uInt16 address, uInt8 value);
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void setBusState(bool& drive, uInt8& value);
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uInt16 address;
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uInt8 value;
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bool yield;
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};
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class ReadStream {
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class BusTransactionQueue {
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public:
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ReadStream();
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BusTransactionQueue();
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void reset();
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void setNextPushAddress(uInt16 address);
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void push(uInt8 value);
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void push(uInt8 value, uInt16 address);
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void injectROM(uInt8 value);
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void injectROM(uInt8 value, uInt16 address);
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void yield();
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bool isYield() const;
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void yield(uInt16 address);
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bool hasPendingRead() const;
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uInt8 pop(uInt16 readAddress);
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bool hasPendingTransaction() const;
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BusTransaction* getNextTransaction(uInt16 address);
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private:
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unique_ptr<ScheduledRead[]> myStream;
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size_t myStreamNext{0};
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size_t myStreamSize{0};
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void push(const BusTransaction& transaction);
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uInt16 myNextPushAddress{0};
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private:
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unique_ptr<BusTransaction[]> myQueue;
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size_t myQueueNext{0};
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size_t myQueueSize{0};
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bool myIsYield{true};
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uInt16 myNextInjectAddress{0};
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};
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private:
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@ -97,7 +111,10 @@ class CartridgeELF: public Cartridge {
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System* mySystem{nullptr};
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unique_ptr<uint8_t[]> myLastPeekResult;
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ReadStream myReadStream;
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BusTransactionQueue myTransactionQueue;
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bool myIsBusDriven{false};
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uInt8 myDriveBusValue{0};
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};
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#endif // CARTRIDGE_ELF
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@ -40,6 +40,8 @@ System::System(Random& random, M6502& m6502, M6532& m6532,
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// Bus starts out unlocked (in other words, peek() changes myDataBusState)
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myDataBusLocked = false;
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myCartridgeDoesBusStuffing = myCart.doesBusStuffing();
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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@ -119,10 +121,12 @@ uInt8 System::peekImpl(uInt16 addr, Device::AccessFlags flags)
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#endif
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// See if this page uses direct accessing or not
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const uInt8 result = access.directPeekBase
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uInt8 result = access.directPeekBase
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? *(access.directPeekBase + (addr & PAGE_MASK))
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: (oob ? access.device->peekOob(addr) : access.device->peek(addr));
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if (!oob && myCartridgeDoesBusStuffing) result = myCart.overdrivePeek(addr, result);
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#ifdef DEBUGGER_SUPPORT
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if(!myDataBusLocked)
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#endif
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@ -141,6 +145,8 @@ uInt8 System::peekImpl<false>(uInt16 addr, Device::AccessFlags flags);
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template<bool oob>
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void System::pokeImpl(uInt16 addr, uInt8 value, Device::AccessFlags flags)
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{
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if (!oob && myCartridgeDoesBusStuffing) value = myCart.overdrivePoke(addr, value);
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const uInt16 page = (addr & ADDRESS_MASK) >> PAGE_SHIFT;
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const PageAccess& access = myPageAccessTable[page];
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@ -445,6 +445,8 @@ class System : public Serializable
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// Some parts of the codebase need to act differently in such a case
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bool mySystemInAutodetect{false};
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bool myCartridgeDoesBusStuffing{false};
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private:
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// Following constructors and assignment operators not supported
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System() = delete;
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