/// <summary>
/// Read a value from the memory at a specific address
/// </summary>
/// <param name="address">The address to read from</param>
/// <returns>Byte The value</returns>
public byte Read(ushort address)
{
if (address < 0x2000) /*RAM*/
{
return(Ram[address & 0x07FF]);
}
if (address < 0x6000) /*IO*/
{
switch (address)
{
case 0x2002:
return(_engine.Ppu.Read2002());
case 0x2004:
return(_engine.Ppu.Read2004());
case 0x2007:
return(_engine.Ppu.Read2007());
case 0x4015:
return(_engine.Apu.Read_4015());
case 0x4016:
{
var v = (byte)(0x40 | (JoyData1 & 1));
JoyData1 = (JoyData1 >> 1) | 0x80;
return(v);
}
case 0x4017:
{
var v = (byte)(0x40 | Zapper.GetData() | (JoyData2 & 1));
JoyData2 = (JoyData2 >> 1) | 0x80;
return(v);
}
default:
if (Map.Cartridge.MapperNo == 225 | Map.Cartridge.MapperNo == 255)
{
var map225 = (Mapper225255)Map.CurrentMapper;
return(map225.ReadRegisters(address));
}
break;
}
}
else if (address < 0x8000) /*SRAM*/
{
if (Map.Cartridge.MapperNo == 5)
{
return(1);
}
return(SRam[address - 0x6000]);
}
else /*PRG*/
{
return(Map.ReadPrg(address));
}
return(0);
}
/// <summary>
/// Read an address from the memory
/// </summary>
/// <param name="address"></param>
/// <returns></returns>
public ushort Read16(ushort address)
{
byte data1;
byte data2;
if (address < 0x2000)
{
data1 = Ram[(address & 0x07FF)];
data2 = Ram[(address & 0x07FF) + 1];
}
else if (address < 0x8000)
{
data1 = SRam[address - 0x6000];
data2 = SRam[(address - 0x6000) + 1];
}
else
{
data1 = Map.ReadPrg(address);
data2 = Map.ReadPrg((ushort)(address + 1));
}
return((ushort)((data2 << 8) | data1));
}