public byte ReadPpuMemory(int address)
{
if (address < 0x3F00)
{
return(_cart.ReadCart(address));
}
else
{
return(paletteRam[address & 0x1F]);
}
}
//Address range Size Device
//$0000-$07FF $0800 2KB internal RAM
//$0800-$0FFF $0800 Mirrors of $0000-$07FF
//$1000-$17FF $0800
//$1800-$1FFF $0800
//$2000-$2007 $0008 NES PPU registers
//$2008-$3FFF $1FF8 Mirrors of $2000-2007 (repeats every 8 bytes)
//$4000-$4017 $0018 NES APU and I/O registers
//$4018-$401F $0008 APU and I/O functionality that is normally disabled.See CPU Test Mode.
//$4020-$FFFF $BFE0 Cartridge space: PRG ROM, PRG RAM, and mapper registers (See Note)
public byte ReadMemory(int address)
{
address &= 0xFFFF;
if (address < 0x2000)
{
return(ram[address & 0x7FF]);
}
else if (address < 0x4000)
{
return(_ppu.ReadPpuRegister(address));
}
else if (address < 0x4020)
{
if (address == 0x4016)
{
int val = 0;
if (strobingPad)
{
val = pad1 & 1;
}
else
{
val = (pad1 >> padShiftCounter++) & 1;
}
return((byte)(val |= 0x40));
}
else
{
return(_apu.ReadApuRegister(address));
}
}
else
{
//$4020-$FFFF $BFE0 Cartridge space: PRG ROM, PRG RAM, and mapper registers (See Note)
return(_cart.ReadCart(address));
}
}