public override void StepVideo(int scanLine, int cycle, bool showBackground, bool showSprites)
{
ppuRendering = scanLine >= 0 && scanLine < 240 && (showBackground || showSprites);
if (cycle != 0)
{
return;
}
if (ppuRendering)
{
if (!inFrame)
{
inFrame = true;
irqCounter = 0;
CancelInterruptRequest?.Invoke();
}
else
{
++irqCounter;
if (irqCounter == irqLatch)
{
irqPending = true;
if (irqEnabled)
{
TriggerInterruptRequest?.Invoke();
}
}
}
}
else
{
inFrame = false;
}
}
private void AcknowledgeInterrupt()
{
if (irqTriggered)
{
CancelInterruptRequest?.Invoke();
irqTriggered = false;
}
}
protected void WriteIrqAcknowledge()
{
if (irqTriggered)
{
CancelInterruptRequest?.Invoke();
}
irqEnable = irqEnableOnAcknowledge;
irqTriggered = false;
}
public override byte this[ushort address]
{
set
{
if (address == 0x8000)
{
// ignore mirror mode set by register $8000 for TC0190
MirrorMode oldMirrorMode = MirrorMode;
base[address] = value;
MirrorMode = oldMirrorMode;
}
else if (address == 0xC000)
{
// irq latch - reload value
irqReload = value;
irqReload ^= 0xFF;
}
else if (address == 0xC001)
{
// irq reload - set irq counter to reload value
irqReloadPrimed = true;
}
else if (address == 0xC002)
{
// enable IRQ
irqEnabled = true;
}
else if (address == 0xC003)
{
// disable IRQ
irqEnabled = false;
CancelInterruptRequest?.Invoke();
}
else if (address == 0xE000)
{
// $E000: [.M.. ....] Mirroring: 0 = Vert, 1 = Horz
MirrorMode = (value & Bin.Bit6) != 0 ? MirrorMode.Horizontal : MirrorMode.Vertical;
}
else
{
// default Taito TC0190 behaviour (mapper 33)
base[address] = value;
}
}
}
public override byte this[ushort address]
{
get
{
if (address < 0x2000)
{
int bank = address / 0x400;
int offset = address % 0x400;
return(Cartridge.CharacterRom[characterRomBank[bank] * 0x400 + offset]);
}
else if (address >= 0x8000)
{
int bank = (address - 0x8000) / 0x2000;
int offset = address % 0x2000;
return(Cartridge.ProgramRom[programRomBank[bank] * 0x2000 + offset]);
}
else
{
return((byte)(address >> 8)); // assuming open bus
}
}
set
{
if (address >= 0x8000 && address < 0xA000)
{
int offset1000 = address % 0x1000;
if (offset1000 >= 4)
{
return;
}
int bankIndex1000 = (address - 0x8000) / 0x1000;
int programBankIndex = bankIndex1000 * 2 + offset1000 / 2;
// last bank must remain fixed
if (programBankIndex > 2)
{
return;
}
int oldProgramBank = programRomBank[programBankIndex];
if (offset1000 % 2 == 0)
{
programRomBank[programBankIndex] = SetLowerNybble(programRomBank[programBankIndex], value);
}
else
{
programRomBank[programBankIndex] = SetHigherNybble(programRomBank[programBankIndex], value);
}
if (programRomBank[programBankIndex] != oldProgramBank)
{
Debug.WriteLine("Program Bank " + programBankIndex + " (" + Hex.Format(address) + ") = " + programRomBank[programBankIndex]);
ProgramBankSwitch?.Invoke((ushort)(0x8000 + programBankIndex * 0x2000), 0x2000);
}
}
else if (address >= 0xA000 && address < 0xE000)
{
int offset1000 = address % 0x1000;
if (offset1000 >= 4)
{
return;
}
int bankIndex1000 = (address - 0xA000) / 0x1000;
int characterBankIndex = bankIndex1000 * 2 + offset1000 / 2;
int oldCharacterBank = characterRomBank[characterBankIndex];
if (offset1000 % 2 == 0)
{
characterRomBank[characterBankIndex] = SetLowerNybble(characterRomBank[characterBankIndex], value);
}
else
{
characterRomBank[characterBankIndex] = SetHigherNybble(characterRomBank[characterBankIndex], value);
}
if (characterRomBank[characterBankIndex] != oldCharacterBank)
{
Debug.WriteLine("Character Bank " + characterBankIndex + " (" + Hex.Format(address) + ") = " + characterRomBank[characterBankIndex]);
CharacterBankSwitch?.Invoke((ushort)(characterBankIndex * 0x400), 0x400);
}
}
else if (address == 0xE000)
{
// bits 0..3 of IRQ counter reload
irqReload &= 0xFFF0;
irqReload |= (ushort)(value & 0x0F);
}
else if (address == 0xE001)
{
// bits 4..7 of IRQ counter reload
irqReload &= 0xFF0F;
irqReload |= (ushort)((value & 0x0F) << 4);
}
else if (address == 0xE002)
{
// bits 8..11 of IRQ counter reload
irqReload &= 0xF0FF;
irqReload |= (ushort)((value & 0x0F) << 8);
}
else if (address == 0xE003)
{
// bits 12..15 of IRQ counter reload
irqReload &= 0x0FFF;
irqReload |= (ushort)((value & 0x0F) << 12);
}
else if (address == 0xF000)
{
irqCounter = irqReload;
Debug.WriteLine("IRQ Reloaded to " + irqReload);
CancelInterruptRequest?.Invoke();
irqPrimed = false;
}
else if (address == 0xF001)
{
irqCounterEnabled = (value & 0x01) != 0;
int counterBits = (value >> 1) & 0x07;
switch (counterBits)
{
case 0: irqFixedMask = 0x0000; break;
case 1: irqFixedMask = 0xF000; break;
case 2:
case 3: irqFixedMask = 0xFF00; break;
default: irqFixedMask = 0xFFF0; break;
}
irqCounterMask = 0xFFFF - irqFixedMask; // complement
CancelInterruptRequest?.Invoke();
irqPrimed = false;
}
else if (address == 0xF002)
{
// mirror mode
switch (value & 0x03)
{
case 0x00: MirrorMode = MirrorMode.Horizontal; break;
case 0x01: MirrorMode = MirrorMode.Vertical; break;
case 0x02: MirrorMode = MirrorMode.Single0; break;
case 0x03: MirrorMode = MirrorMode.Single1; break;
}
}
}
}
public override byte this[ushort address]
{
get
{
int bankOffset = address % characterBankSize;
// character ROM
if (address < 0x2000)
{
// handle extended mode - bank registers from extended ram page
if (extendedRamMode == 1 && !AccessingSpriteCharacters)
{
bankOffset = address % 0x1000;
int extendedCharacterBank = extendedRam[lastTileIndex];
extendedCharacterBank &= 0x3F;
extendedCharacterBank |= (characterBankUpper >> 2);
return(Cartridge.CharacterRom[extendedCharacterBank * 0x1000 + bankOffset]);
}
// handles all CHR modes
// bank range CHR modes 8K: [0], 4K: [0, 1] 2K: [0..3], 1k: [0..7]
int bankRange = address / characterBankSize;
// determine stride between bank registers, given CHR mode: 8K: 8, 4K: 4, 2K: 2, 1K: 1
int indexStride = characterBankSize / 0x0400;
// determine bank index: 8K: [7], 4k: [3, 7], 2K: [1, 3, 5, 7], 8K: [0..7]
int bankIndex = (bankRange + 1) * indexStride - 1;
// if sprite mode is 8x16 and chr access if for background, use upper
// bank switching register indexes 8K: [11], 4k: [11], 2K: [9, 11], 8K: [8..11]
// or
// sprite mode is 8x8 and last register banks written are upper
if ((SpriteSize == Video.SpriteSize.Size8x16 && !AccessingSpriteCharacters) ||
(SpriteSize == Video.SpriteSize.Size8x8 && characterBankLastWrittenUpper))
{
bankIndex %= 4;
bankIndex += 8;
}
int characterBank = characterBanks[bankIndex];
int addressBase = characterBank * characterBankSize;
return(Cartridge.CharacterRom[addressBase + bankOffset]);
}
if (address >= 0x5000 && address <= 0x5007)
{
// TODO: pulse generators 1 and 2
return(0x00);
}
if (address == 0x5010 || address == 0x5011 || address == 0x5015)
{
// TODO: irq, pcm, status
return(0x00);
}
// read-only IRQ counter - return open bus?
if (address == 0x5203)
{
return(0x52);
}
if (address == 0x5204)
{
byte result = 0;
if (irqPending)
{
result |= 0x80;
}
if (inFrame)
{
result |= 0x40;
}
irqPending = false;
CancelInterruptRequest?.Invoke();
return(result);
}
if (address == 0x5205)
{
return(productLow);
}
if (address == 0x5206)
{
return(productHigh);
}
if (address >= 0x5C00 && address < 0x6000)
{
// expansion ram - all modes
switch (extendedRamMode)
{
case 0:
case 1:
// expansion ram mode 0/1 - returns open bus
return((byte)(address >> 8));
case 2:
// expansion ram mode 2 - 1K r/w memory
case 3:
// expansion ram mode 3 - 1K ROM
return(extendedRam[address % 0x400]);
default:
throw new Exception("MMC5 Invalid expansion ram mode");
}
}
if (address >= 0x6000 && address < 0x8000)
{
// all bank modes - 8K switchable RAM bank
int offset = address % 0x2000;
return(programRam[programRamBank * 0x2000 + offset]);
}
if (address >= 0x8000)
{
// program banks for all modes
switch (programBankMode)
{
case 0:
{
// PRG mode 0 - single 32k switchable ROM bank
int offset = address % 0x8000;
return(Cartridge.ProgramRom[(programRomBank >> 2) * 0x8000 + offset]);
}
case 1:
if (address < 0xC000)
{
// PRG mode 1 - first 16k switchable ROM/RAM bank
int offset = address % 0x4000;
int flatAddress = (programBank1 >> 1) * 0x4000 + offset;
if (romMode1)
{
return(Cartridge.ProgramRom[flatAddress]);
}
else
{
return(programRam[flatAddress]);
}
}
else // if (address >= 0xC000)
{
// PRG mode 1 - second 16k switchable ROM bank
int offset = address % 0x4000;
return(Cartridge.ProgramRom[programRomBank * 0x4000 + offset]);
}
case 2:
if (address < 0xC000)
{
// PRG mode 2 - 16k switchable ROM/RAM bank
int offset = address % 0x4000;
int flatAddress = (programBank1 >> 1) * 0x4000 + offset;
if (romMode1)
{
return(Cartridge.ProgramRom[flatAddress]);
}
else
{
return(programRam[flatAddress]);
}
}
else if (address < 0xE000)
{
// PRG mode 2 - first 8k switchable ROM/RAM bank
int offset = address % 0x2000;
int flatAddress = programBank2 * 0x2000 + offset;
if (romMode2)
{
return(Cartridge.ProgramRom[flatAddress]);
}
else
{
return(programRam[flatAddress]);
}
}
else // if (address >= 0xE000 )
{
// PRG mode 2 - second 8k switchable ROM bank
int offset = address % 0x2000;
return(Cartridge.ProgramRom[programRomBank * 0x2000 + offset]);
}
case 3:
if (address < 0xA000)
{
// PRG mode 3 - first 8k switchable ROM/RAM bank
int offset = address % 0x2000;
int flatAddress = programBank0 * 0x2000 + offset;
if (romMode0)
{
return(Cartridge.ProgramRom[flatAddress]);
}
else
{
return(programRam[flatAddress]);
}
}
else if (address < 0xC000)
{
// PRG mode 3 - second 8k switchable ROM/RAM bank
int offset = address % 0x2000;
int flatAddress = programBank1 * 0x2000 + offset;
if (romMode1)
{
return(Cartridge.ProgramRom[flatAddress]);
}
else
{
return(programRam[flatAddress]);
}
}
else if (address < 0xE000)
{
// PRG mode 3 - third 8k switchable ROM/RAM bank
int offset = address % 0x2000;
int flatAddress = programBank2 * 0x2000 + offset;
if (romMode2)
{
return(Cartridge.ProgramRom[flatAddress]);
}
else
{
return(programRam[flatAddress]);
}
}
else // if (address >= 0xE000)
{
// PRG mode 3 - fourth 8k switchable ROM bank
int offset = address % 0x2000;
return(Cartridge.ProgramRom[programRomBank * 0x2000 + offset]);
}
default:
throw new Exception("MMC5 Invalid program bank mode");
}
}
// invalid / unhandled addresses
//throw new Exception("Unhandled " + Name + " mapper read at address: " + Hex.Format(address));
// return open bus for unhandled read
return((byte)(address >> 8));
}
set
{
// character ROM
if (address < 0x2000)
{
// handles all CHR modes
// bank range CHR modes 8K: [0], 4K: [0, 1] 2K: [0..3], 1k: [0..7]
int bankRange = address / characterBankSize;
// determine stride between bank registers, given CHR mode: 8K: 8, 4K: 4, 2K: 2, 1K: 1
int indexStride = characterBankSize / 0x0400;
// determine bank index: 8K: [7], 4k: [3, 7], 2K: [1, 3, 5, 7], 8K: [0..7]
int bankIndex = (bankRange + 1) * indexStride - 1;
// if sprite mode is 8x16 and chr access if for background, use upper
// bank switching register indexes 8K: [11], 4k: [11], 2K: [9, 11], 8K: [8..11]
// or
// sprite mode is 8x8 and last register banks written are upper
if ((SpriteSize == Video.SpriteSize.Size8x16 && !AccessingSpriteCharacters) ||
(SpriteSize == Video.SpriteSize.Size8x8 && characterBankLastWrittenUpper))
{
bankIndex %= 4;
bankIndex += 8;
}
int characterBank = characterBanks[bankIndex];
int addressBase = characterBank * characterBankSize;
int bankOffset = address % characterBankSize;
Cartridge.CharacterRom[addressBase + bankOffset] = value;
return;
}
// registers
if (address >= 0x5000 && address <= 0x5007)
{
// TODO: pulse generators 1 and 2
return;
}
if (address == 0x5010 || address == 0x5011 || address == 0x5015)
{
// TODO: irq, pcm, status
return;
}
if (address == 0x5100)
{
programBankMode = (byte)(value & 0x03);
Debug.WriteLine("MMC5 PRG Bank Mode ($5100) = " + Hex.Format(programBankMode));
return;
}
if (address == 0x5101)
{
SetCharacterBankMode((byte)(value & 0x03));
Debug.WriteLine("MMC5 CHR Bank Mode ($5101) = " + Hex.Format(characterBankMode) + " (" + characterBankCount + " " + characterBankSize + "b Banks)");
return;
}
if (address == 0x5102)
{
programRamProtect1 = value == 2;
programRamProtect = programRamProtect1 && programRamProtect2;
Debug.WriteLine("MMC5 Ram Protect 1 ($5103) = " + (programRamProtect1 ? "Enabled" : "Disabled") + " (P1 && P2 = " + programRamProtect + ")");
return;
}
if (address == 0x5103)
{
programRamProtect2 = value == 1;
programRamProtect = programRamProtect1 && programRamProtect2;
Debug.WriteLine("MMC5 Ram Protect 2 ($5103) = " + (programRamProtect2 ? "Enabled" : "Disabled") + " (P1 && P2 = " + programRamProtect + ")");
return;
}
if (address == 0x5104)
{
extendedRamMode = (byte)(value & 0x03);
Debug.WriteLine("MMC5 ExRamMode ($5104) = " + Hex.Format((byte)extendedRamMode));
return;
}
if (address == 0x5105)
{
// Mirror mode - DD CC BB AA
MirrorMode = (MirrorMode)value;
Debug.WriteLine("MMC5 Mirror Mode ($5105) = " + MirrorMode + " (" + Hex.Format((byte)MirrorMode) + ") (" + Bin.Format((byte)MirrorMode) + ")");
return;
}
if (address == 0x5106)
{
fillModeTile = value;
Debug.WriteLine("MMC5 Fill Mode Tile ($5106) = " + Hex.Format(fillModeTile));
return;
}
if (address == 0x5107)
{
int attrbibutes = value & 0x03;
// replicate bits 0,1 to rest of byte ------AB -> ABABABAB
fillModeAttributes = (byte)(attrbibutes | (attrbibutes << 2) | (attrbibutes << 4) | (attrbibutes << 6));
Debug.WriteLine("MMC5 Fill Mode Attributes ($5107) = " + Hex.Format((byte)attrbibutes));
return;
}
if (address == 0x5113)
{
//---- -CBB : C: chip, BB: bank within chip (CBB can be treated as 8 banks)
programRamBank = (byte)(value & 0x07);
Debug.WriteLine("MMC5 PRG RAM Bank ($5113) = " + Hex.Format(programRamBank));
return;
}
if (address == 0x5114)
{
//RBBB BBBB : R - ROM mode, BBBBBBB - bank number
romMode0 = (value & 0x80) != 0;
programBank0 = (byte)(value & 0x7F);
Debug.WriteLine("MMC5 PRG ROM/RAM Bank 0 ($5114) = " + Hex.Format(programBank0) + " in " + (romMode0 ? "ROM" : "RAM") + " mode");
return;
}
if (address == 0x5115)
{
//RBBB BBBB : R - ROM mode, BBBBBBB - bank number
romMode1 = (value & 0x80) != 0;
programBank1 = (byte)(value & 0x7F);
Debug.WriteLine("MMC5 PRG ROM/RAM Bank 1 ($5115) = " + Hex.Format(programBank1) + " in " + (romMode1 ? "ROM" : "RAM") + " mode");
return;
}
if (address == 0x5116)
{
//RBBB BBBB : R - ROM mode, BBBBBBB - bank number
romMode2 = (value & 0x80) != 0;
programBank2 = (byte)(value & 0x7F);
Debug.WriteLine("MMC5 PRG ROM/RAM Bank 2 ($5116) = " + Hex.Format(programBank2) + " in " + (romMode2 ? "ROM" : "RAM") + " mode");
return;
}
if (address == 0x5117)
{
//-BBB BBBB : BBBBBBB - bank number
programRomBank = (byte)(value & 0x7F);
Debug.WriteLine("MMC5 PRG ROM Bank Register ($5117) = " + Hex.Format(programRomBank));
return;
}
if (address >= 0x5120 && address <= 0x512B)
{
if (characterBankCount == 0)
{
return;
}
characterBankLastWrittenUpper = address > 0x5127;
ushort characterBank = 0;
// merge low bits
characterBank |= value;
// merge high bits
characterBank |= characterBankUpper;
// ensure within available banks
characterBank %= characterBankCount;
// assign to corresponding bank switch
characterBanks[address - 0x5120] = characterBank;
Debug.WriteLine("MMC5 CHR Bank Register (" + Hex.Format(address) + ") = " + Hex.Format(value) + " (" + Hex.Format(characterBank) + ")");
return;
}
if (address == 0x5130)
{
// upper 2 bits (bit 8, 9) for character bank selection (all banks)
characterBankUpper = value;
characterBankUpper &= 0x03;
Debug.WriteLine("MMC5 Upper CHR Bits ($5130) = " + Bin.Format((byte)characterBankUpper));
characterBankUpper <<= 8;
return;
}
if (address == 0x5200)
{
//ES-W WWWW
verticalSplitModeEnabled = (value & 0x80) != 0;
verticalSplitSide = (VerticalSplitSide)((value >> 6) & 0x01);
verticalSplitStartStopTile = (byte)(value & 0x1F);
return;
}
if (address == 0x5203)
{
irqLatch = value;
Debug.WriteLine("MMC5 IRQ Counter($5203) = " + irqLatch);
return;
}
if (address == 0x5204)
{
irqEnabled = (value & 0x80) != 0;
Debug.WriteLine("MMC5 IRQ ($5204) = " + (irqEnabled ? "Enabled" : "Disabled"));
return;
}
if (address == 0x5205)
{
factor1 = value;
EvaluateProduct();
Debug.WriteLine("MMC5 Mul Factor 1 ($5205) = " + Hex.Format(factor1) + " (Result High: " + Hex.Format(productHigh) + ", Low: " + Hex.Format(productLow) + ")");
return;
}
if (address == 0x5206)
{
factor2 = value;
EvaluateProduct();
Debug.WriteLine("MMC5 Mul Factor 2 ($5205) = " + Hex.Format(factor1) + " (Result High: " + Hex.Format(productHigh) + ", Low: " + Hex.Format(productLow) + ")");
return;
}
if (address >= 0x5C00 && address < 0x6000)
{
// expansion ram - all modes
Debug.WriteLine("MMC5 Write to Extended RAM (" + Hex.Format(address) + ") = " + Hex.Format(value));
switch (extendedRamMode)
{
case 0:
case 1:
// expansion ram mode 0/1 - writes allowed when ppu rendering, otherwise zero written
extendedRam[address % 0x400] = ppuRendering ? value : (byte)0;
return;
case 2:
// expansion ram mode 2 - 1K r/w memory
extendedRam[address % 0x400] = value;
return;
case 3:
// expansion ram mode 3 - 1K ROM (read only - do nothing?)
return;
default:
throw new Exception("MMC5 Invalid expansion ram mode");
}
}
if (address >= 0x6000 && address < 0x8000)
{
// all bank modes - 8K switchable RAM bank
int offset = address % 0x2000;
programRam[programRamBank * 0x2000 + offset] = value;
return;
}
if (address >= 0x8000)
{
// program banks for all modes
switch (programBankMode)
{
case 0:
{
// PRG mode 0 - single 32k switchable ROM bank
return;
}
case 1:
if (address < 0xC000)
{
// PRG mode 1 - first 16k switchable ROM/RAM bank
if (!romMode1 && !programRamProtect)
{
int offset = address % 0x4000;
programRam[(programBank1 >> 1) * 0x4000 + offset] = value;
}
return;
}
else // if (address >= 0xC000)
{
// PRG mode 1 - second 16k switchable ROM bank
return;
}
case 2:
if (address < 0xC000)
{
// PRG mode 2 - 16k switchable ROM/RAM bank
if (!romMode1 && !programRamProtect)
{
int offset = address % 0x4000;
programRam[(programBank1 >> 1) * 0x4000 + offset] = value;
}
return;
}
else if (address < 0xE000)
{
// PRG mode 2 - first 8k switchable ROM/RAM bank
if (!romMode2 && !programRamProtect)
{
int offset = address % 0x2000;
programRam[programBank2 * 0x2000 + offset] = value;
}
return;
}
else // if (address >= 0xE000 )
{
// PRG mode 2 - second 8k switchable ROM bank
return;
}
case 3:
if (address < 0xA000)
{
// PRG mode 3 - first 8k switchable ROM/RAM bank
if (!romMode0 && !programRamProtect)
{
int offset = address % 0x2000;
programRam[programBank0 * 0x2000 + offset] = value;
}
return;
}
else if (address < 0xC000)
{
// PRG mode 3 - second 8k switchable ROM/RAM bank
if (!romMode1 && !programRamProtect)
{
int offset = address % 0x2000;
programRam[programBank1 * 0x2000 + offset] = value;
}
return;
}
else if (address < 0xE000)
{
// PRG mode 3 - third 8k switchable ROM/RAM bank
if (!romMode2 && !programRamProtect)
{
int offset = address % 0x2000;
programRam[programBank2 * 0x2000 + offset] = value;
}
return;
}
else // if (address >= 0xE000)
{
// PRG mode 3 - fourth 8k switchable ROM bank
return;
}
default:
throw new Exception("MMC5 Invalid program bank mode");
}
}
// invalid / unhandled addresses
throw new Exception("Unhandled " + Name + " mapper write at address: " + Hex.Format(address));
}
}
public override byte this[ushort address]
{
get
{
if (address < 0x2000)
{
if (characterBanksSupported)
{
// get data from corresponding 1K bank
int bankindex = address / 0x400;
int bankOffset = address % 0x400;
return(Cartridge.CharacterRom[characterBank[bankindex] * 0x400 + bankOffset]);
}
else
{
// for Datach Joint ROM System - treat as flat CHR RAM
return(Cartridge.CharacterRom[address]);
}
}
if (address >= 0x6000 && address < 0x7FFF)
{
// return SRAM or open bus depending on variant
return(saveRamSupported ? Cartridge.SaveRam[(ushort)(address - 0x6000)] : (byte)(address >> 8));
}
if (address >= 0x8000 && address < 0xC000)
{
int bankOffset = address % 0x4000;
return(Cartridge.ProgramRom[outerProgramBank + programBank * 0x4000 + bankOffset]);
}
if (address >= 0xC000)
{
// fixed at last bank
int lastBankOffset = address % 0x4000;
return(Cartridge.ProgramRom[outerProgramBank + lastProgramBankBase + lastBankOffset]);
}
//if (address >= 0x6000)
// return Cartridge.SaveRam[(ushort)(address - 0x6000)];
//throw new Exception("Unhandled " + Name + " mapper read at address: " + Hex.Format(address));
// return open bus?
return((byte)(address >> 8));
}
set
{
if (address < 0x2000)
{
if (characterBanksSupported)
{
// CHR bank switches for 8 0x400 ranges
// set CHR bank for corresponding 0x400 range
int bankindex = address / 0x400;
int bankOffset = address % 0x400;
Cartridge.CharacterRom[characterBank[bankindex] * 0x400 + bankOffset] = value;
}
else
{
// for Datach Joint ROM System - treat as flat CHR RAM
Cartridge.CharacterRom[address] = value;
}
}
else if (saveRamSupported && address >= 0x6000 && address < 0x8000)
{
Cartridge.SaveRam[(ushort)(address - 0x6000)] = value;
}
else if (address >= registerBase)
{
// NOTE: FCG variants vary register base between $6000 and $8000
// variants lumped under mapper 16 require mirroring these bases to get most games to work
int registerAddress = address % 0x10;
if (outerProgramBankSupported && address >= 0x8000 && address < 0x8004)
{
int oldOuterProgramBank = outerProgramBank;
// outer program bank (mapper 153 only)
if ((value & 0x01) != 0)
{
outerProgramBank = 0x40000;
}
else
{
outerProgramBank = 0;
}
if (outerProgramBank != oldOuterProgramBank)
{
ProgramBankSwitch?.Invoke(0x8000, 0x8000);
}
}
else if (characterBanksSupported && registerAddress < 0x08)
{
// CHR bank switch
int oldCharacterBank = characterBank[registerAddress];
characterBank[registerAddress] = value;
if (value != oldCharacterBank)
{
CharacterBankSwitch?.Invoke((ushort)(registerAddress * 0x400), 0x400);
}
}
else if (registerAddress == 0x08)
{
// program bank switch
int oldProgramBank = programBank;
programBank = value & 0x0F;
programBank %= programBankCount; // probably not needed, but anyhow
// invalidate address region
if (programBank != oldProgramBank)
{
ProgramBankSwitch?.Invoke(0x8000, 0x4000);
}
}
else if (registerAddress == 0x09)
{
// mirroring mode
switch (value & 0x03)
{
case 0: MirrorMode = MirrorMode.Vertical; break;
case 1: MirrorMode = MirrorMode.Horizontal; break;
case 2: MirrorMode = MirrorMode.Single0; break;
case 3: MirrorMode = MirrorMode.Single1; break;
}
}
else if (registerAddress == 0x0A)
{
irqEnabled = (value & 0x01) != 0;
CancelInterruptRequest?.Invoke();
}
else if (registerAddress == 0x0B)
{
irqCounter &= 0xFF00;
irqCounter |= value;
}
else if (registerAddress == 0x0C)
{
irqCounter &= 0x00FF;
irqCounter |= (ushort)(value << 8);
}
// TODO: D: eeprom/PRG ram enable
// TODO: variants
}
else
{
throw new Exception("Unhandled " + Name + " mapper write at address: " + Hex.Format(address));
//ignore writes?
}
}
}
