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FDS: Improved open bus behavior for register reads (fixes Super Lode Runner)

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This commit is contained in:
Souryo 2017-05-22 11:18:12 -04:00
parent 3da14db83d
commit 3a55cfeea9
2 changed files with 18 additions and 9 deletions
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10
Core/FDS.cpp
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@ -375,12 +375,15 @@ bool FDS::IsDiskInserted()
uint8_t FDS::ReadRegister(uint16_t addr)
{
uint8_t value = 0;
uint8_t value = MemoryManager::GetOpenBus();
if(_soundRegEnabled && addr >= 0x4040) {
return _audio->ReadRegister(addr);
} else if(_diskRegEnabled && addr <= 0x4033) {
switch(addr) {
case 0x4030:
//These 3 pins are open bus
value &= 0x2C;
value |= CPU::HasIRQSource(IRQSource::External) ? 0x01 : 0x00;
value |= _transferComplete ? 0x02 : 0x00;
value |= _badCrc ? 0x10 : 0x00;
@ -398,6 +401,9 @@ uint8_t FDS::ReadRegister(uint16_t addr)
return _readDataReg;
case 0x4032:
//These 5 pins are open bus
value &= 0xF8;
value |= !IsDiskInserted() ? 0x01 : 0x00; //Disk not in drive
value |= (!IsDiskInserted() || !_scanningDisk) ? 0x02 : 0x00; //Disk not ready
value |= !IsDiskInserted() ? 0x04 : 0x00; //Disk not writable
@ -413,7 +419,7 @@ uint8_t FDS::ReadRegister(uint16_t addr)
case 0x4033:
//Always return good battery
return 0x80 & _extConWriteReg;
return _extConWriteReg;
}
}

17
Core/FdsAudio.h
View file

@ -90,16 +90,19 @@ protected:
public:
uint8_t ReadRegister(uint16_t addr)
{
uint8_t value = MemoryManager::GetOpenBus();
if(addr <= 0x407F) {
return 0x40 | _waveTable[addr & 0x3F];
} else {
switch(addr) {
case 0x4090: return 0x40 | _volume.GetGain();
case 0x4092: return 0x40 | _mod.GetGain();
}
value &= 0xC0;
value |= _waveTable[addr & 0x3F];
} else if(addr == 0x4090) {
value &= 0xC0;
value |= _volume.GetGain();
} else if(addr == 0x4092) {
value &= 0xC0;
value |= _mod.GetGain();
}
return MemoryManager::GetOpenBus();
return value;
}
void WriteRegister(uint16_t addr, uint8_t value)