mirror of
https://github.com/MoleskiCoder/EightBit.git
synced 2024-09-02 07:28:56 +00:00
Start a more careful documentation of the I/O registers.
Signed-off-by: Adrian.Conlon <adrian.conlon@gmail.com>
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@ -89,6 +89,24 @@ namespace EightBit {
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Keypad = Processor::Bit3 // Hi-Lo of P10-P13
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};
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enum LcdcControl {
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DisplayBackground = Processor::Bit0,
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ObjectEnable = Processor::Bit1,
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ObjectBlockCompositionSelection = Processor::Bit2,
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BackgroundCodeAreaSelection = Processor::Bit3,
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BackgroundCharacterDataSelection = Processor::Bit4,
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WindowEnable = Processor::Bit5,
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WindowCodeAreaSelection = Processor::Bit6,
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LcdEnable = Processor::Bit7
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};
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enum LcdStatusMode {
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CpuAccessAllowed = 0b00,
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VerticalBlankingPeriod = 0b01,
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SearchingOamRam = 0b10,
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TransferringDataToLcd = 0b11
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};
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Bus();
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void reset();
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@ -96,17 +114,25 @@ namespace EightBit {
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virtual void clear() override;
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void triggerInterrupt(int cause) {
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writeRegister(IF, readRegister(IF) | cause);
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pokeRegister(IF, peekRegister(IF) | cause);
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}
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void writeRegister(int offset, uint8_t content) {
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return Memory::write(BASE + offset, content);
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Memory::write(BASE + offset, content);
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}
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void pokeRegister(int offset, uint8_t content) {
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poke(BASE + offset, content);
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}
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uint8_t readRegister(int offset) {
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return Memory::read(BASE + offset);
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}
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uint8_t peekRegister(int offset) {
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return peek(BASE + offset);
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}
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void checkTimers(int cycles);
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int timerClockTicks() {
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@ -126,7 +152,7 @@ namespace EightBit {
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}
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int timerClock() {
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return readRegister(TAC) & Processor::Mask2;
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return peekRegister(TAC) & Processor::Mask2;
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}
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bool timerEnabled() {
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@ -134,29 +160,29 @@ namespace EightBit {
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}
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bool timerDisabled() {
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return (readRegister(TAC) & Processor::Bit2) == 0;
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return (peekRegister(TAC) & Processor::Bit2) == 0;
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}
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void incrementDIV() {
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auto current = readRegister(DIV);
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writeRegister(DIV, ++current);
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auto current = peekRegister(DIV);
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pokeRegister(DIV, ++current);
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}
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void incrementTIMA() {
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uint16_t updated = readRegister(TIMA) + 1;
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uint16_t updated = peekRegister(TIMA) + 1;
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if (updated & Processor::Bit8) {
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triggerInterrupt(TimerOverflow);
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updated = readRegister(TMA);
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updated = peekRegister(TMA);
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}
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writeRegister(TIMA, updated & Processor::Mask8);
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pokeRegister(TIMA, updated & Processor::Mask8);
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}
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void incrementLY() {
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writeRegister(LY, (readRegister(LY) + 1) % TotalLineCount);
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pokeRegister(LY, (peekRegister(LY) + 1) % TotalLineCount);
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}
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void resetLY() {
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writeRegister(LY, 0);
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pokeRegister(LY, 0);
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}
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void disableBootRom() { m_disableBootRom = true; }
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@ -21,8 +21,8 @@ EightBit::Bus::Bus()
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}
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void EightBit::Bus::reset() {
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writeRegister(NR52, 0xf1);
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writeRegister(LCDC, 0x91);
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pokeRegister(NR52, 0xf1);
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pokeRegister(LCDC, DisplayBackground | BackgroundCharacterDataSelection | LcdEnable);
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}
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void EightBit::Bus::clear() {
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@ -102,16 +102,63 @@ void EightBit::Bus::Bus_WrittenByte(const AddressEventArgs& e) {
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if (!handled) {
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switch (address) {
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case BASE + TAC:
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m_timerRate = timerClockTicks();
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case BASE + SB: // R/W
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case BASE + SC: // R/W
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break;
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case BASE + BOOT_DISABLE:
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m_disableBootRom = value != 0;
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break;
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case BASE + DIV:
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case BASE + DIV: // R/W
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Memory::reference() = 0;
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m_timerCounter = 0;
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break;
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case BASE + TIMA: // R/W
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case BASE + TMA: // R/W
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break;
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case BASE + TAC: // R/W
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m_timerRate = timerClockTicks();
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break;
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case BASE + IF: // R/W
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break;
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case BASE + NR10:
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case BASE + NR11:
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case BASE + NR12:
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case BASE + NR13:
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case BASE + NR14:
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case BASE + NR22:
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case BASE + NR24:
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case BASE + NR30:
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case BASE + NR42:
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case BASE + NR44:
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case BASE + NR50:
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case BASE + NR51:
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case BASE + NR52:
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break;
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case BASE + LCDC:
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case BASE + STAT:
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case BASE + SCY:
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case BASE + SCX:
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case BASE + DMA:
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break;
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case BASE + LY: // R/O
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Memory::reference() = 0;
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break;
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case BASE + BGP:
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case BASE + OBP0:
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case BASE + OBP1:
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case BASE + WY:
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case BASE + WX:
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break;
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case BASE + BOOT_DISABLE:
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m_disableBootRom = value != 0;
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break;
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default:
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if ((address > BASE) && (address < (BASE + 0x4c)))
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assert(false);
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}
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}
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}
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@ -332,14 +332,14 @@ void EightBit::LR35902::ccf(uint8_t& a, uint8_t& f) {
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int EightBit::LR35902::run(int limit) {
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int current = 0;
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do {
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auto interruptEnable = m_bus.readRegister(Bus::IE);
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auto interruptFlags = m_bus.readRegister(Bus::IF);
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auto interruptEnable = m_bus.peekRegister(Bus::IE);
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auto interruptFlags = m_bus.peekRegister(Bus::IF);
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auto ime = IME();
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auto masked = interruptEnable & interruptFlags;
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if (masked) {
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if (ime) {
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m_bus.writeRegister(Bus::IF, 0);
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m_bus.pokeRegister(Bus::IF, 0);
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} else {
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if (isHalted())
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proceed();
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