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Atari 2600 - implement SB mapper (Super banking)

This commit is contained in:
adelikat 2014-04-09 02:17:45 +00:00
parent 37139822ac
commit 2834e80dfa
1 changed files with 67 additions and 3 deletions
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70
BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/mSB.cs
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@ -1,4 +1,4 @@
using System;
using BizHawk.Common;
namespace BizHawk.Emulation.Cores.Atari.Atari2600
{
@ -8,9 +8,73 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
*/
internal class mSB : MapperBase
{
public mSB()
private int _bank4K;
private int myStartBank
{
throw new NotImplementedException();
get { return (Core.Rom.Length >> 12) - 1; }
}
public override void SyncState(Serializer ser)
{
base.SyncState(ser);
ser.Sync("bank_4k", ref _bank4K);
}
public override void HardReset()
{
_bank4K = 0;
base.HardReset();
}
private byte ReadMem(ushort addr, bool peek)
{
if (!peek)
{
Address(addr);
}
if (addr < 0x1000)
{
return base.ReadMemory(addr);
}
return Core.Rom[(_bank4K << 12) + (addr & 0xFFF)];
}
public override byte ReadMemory(ushort addr)
{
return ReadMem(addr, false);
}
public override byte PeekMemory(ushort addr)
{
return ReadMem(addr, true);
}
public override void WriteMemory(ushort addr, byte value)
{
Address(addr);
if (addr < 0x1000)
{
base.WriteMemory(addr, value);
}
}
private void Address(ushort addr)
{
var temp = addr & (0x17FF + (Core.Rom.Length >> 12));
if ((temp & 0x1800) == 0x800)
{
_bank4K = temp & myStartBank;
}
//switch (addr & 0x1840)
//{
// case 0x0800:
// _bank4K = 0;
// break;
// case 0x0840:
// _bank4K = 1;
// break;
//}
}
}
}