/// <summary>
/// Reads the PPU registers available in the addresses $2000-$2007 from the CPU memory map.
/// </summary>
/// <param name="address">The PPU register address.</param>
/// <returns>The value allocated in the register identified by the given address.</returns>
private byte ReadPpuRegister(ushort address)
{
CatchupPpu();
byte value = 0;
switch (address)
{
// PPU Control register (write only)
case 0x2000:
break;
// PPU Mask register (write only)
case 0x2001:
break;
// PPU Status register
case 0x2002:
value = (byte)_ppu.Status.Status;
// Side effects of reading the status register
_ppu.Status.VerticalBlank = false; // Clears bit 7 (V-BLANK) flag after CPU read the status register
_ppu.ResetAddressLatch();
break;
// PPU OAM address register (write only)
case 0x2003:
break;
// PPU OAM data register
case 0x2004:
//value = _ppu.OamData;
value = _ppu.OamData;
break;
// PPU Scroll register (write only)
case 0x2005:
break;
// PPU Address register (write only)
case 0x2006:
break;
// PPU Data register
case 0x2007:
value = _ppu.PpuData;
break;
}
return(value);
}