BizHawk/EMU7800/Core/Cart78SGP.cs

118 lines
3.3 KiB
C#

namespace EMU7800.Core
{
/// <summary>
/// Atari 7800 SuperGame bankswitched cartridge w/Pokey
/// </summary>
public sealed class Cart78SGP : Cart
{
//
// Cart Format Mapping to ROM Address Space
// Bank0: 0x00000:0x4000
// Bank1: 0x04000:0x4000 0x4000:0x4000 Pokey
// Bank2: 0x08000:0x4000 0x8000:0x4000 Bank0-7 (0 on startup)
// Bank3: 0x0c000:0x4000 0xc000:0x4000 Bank7
// Bank4: 0x10000:0x4000
// Bank5: 0x14000:0x4000
// Bank6: 0x18000:0x4000
// Bank7: 0x1c000:0x4000
//
readonly int[] _bank = new int[4];
PokeySound _pokeySound;
#region IDevice Members
public override void Reset()
{
base.Reset();
if (_pokeySound != null)
_pokeySound.Reset();
}
public override byte this[ushort addr]
{
get
{
var bankNo = addr >> 14;
switch (bankNo)
{
case 1:
return (_pokeySound != null) ? _pokeySound.Read(addr) : (byte)0;
default:
return ROM[(_bank[bankNo] << 14) | (addr & 0x3fff)];
}
}
set
{
var bankNo = addr >> 14;
switch (bankNo)
{
case 1:
if (_pokeySound != null)
_pokeySound.Update(addr, value);
break;
case 2:
_bank[2] = value & 7;
break;
}
}
}
#endregion
public override void Attach(MachineBase m)
{
base.Attach(m);
if (_pokeySound == null)
_pokeySound = new PokeySound(M);
}
public override void StartFrame()
{
if (_pokeySound != null)
_pokeySound.StartFrame();
}
public override void EndFrame()
{
if (_pokeySound != null)
_pokeySound.EndFrame();
}
private Cart78SGP()
{
}
public Cart78SGP(byte[] romBytes)
{
_bank[2] = 0;
_bank[3] = 7;
LoadRom(romBytes, 0x20000);
}
#region Serialization Members
public Cart78SGP(DeserializationContext input, MachineBase m) : base(input)
{
input.CheckVersion(1);
LoadRom(input.ReadBytes());
_bank = input.ReadIntegers(4);
_pokeySound = input.ReadOptionalPokeySound(m);
}
public override void GetObjectData(SerializationContext output)
{
if (_pokeySound == null)
throw new Emu7800SerializationException("Cart78SGP must be attached before serialization.");
base.GetObjectData(output);
output.WriteVersion(1);
output.Write(ROM);
output.Write(_bank);
output.WriteOptional(_pokeySound);
}
#endregion
}
}