using System;
using System.Collections.Generic;
using System.IO;
using BizHawk.Emulation.CPUs.M6502;
using BizHawk.Emulation.Consoles.Atari;

namespace BizHawk
{
	partial class Atari2600
	{
		/*
		F8 (Atari style 8K)
		-----

		This is the fairly standard way 8K of cartridge ROM was implemented.  There are two
		4K ROM banks, which get mapped into the 4K of cartridge space.  Accessing 1FF8 or
		1FF9 selects one of the two 4K banks.  When one of these two addresses are accessed,
		the banks switch spontaniously.

		ANY kind of access will trigger the switching- reading or writing.  Usually games use
		LDA or BIT on 1FF8/1FF9 to perform the switch.

		When the switch occurs, the entire 4K ROM bank switches, including the code that is
		reading the 1FF8/1FF9 location.  Usually, games put a small stub of code in BOTH banks
		so when the switch occurs, the code won't crash.
		*/

		class mF8 : MapperBase
		{
			int bank_4k = 0;

			public override byte ReadMemory(ushort addr)
			{
				Address(addr);
				if (addr < 0x1000) return base.ReadMemory(addr);
				return core.rom[(bank_4k << 12) + (addr&0xFFF)];
			}
			public override void WriteMemory(ushort addr, byte value)
			{
				Address(addr);
				if (addr < 0x1000) base.WriteMemory(addr, value);
			}

			public override void SyncState(Serializer ser)
			{
				base.SyncState(ser);
				ser.Sync("toggle", ref bank_4k);
			}

			void Address(ushort addr)
			{
				if (addr == 0x1FF8) bank_4k = 0;
				else if (addr == 0x1FF9) bank_4k = 1;
			}
		}
	}
}