BizHawk/BizHawk.Emulation.Cores/Consoles/PC Engine/MemoryMap.SF2.cs

using BizHawk.Common;

namespace BizHawk.Emulation.Cores.PCEngine
{
	public partial class PCEngine
	{
		// Street Fighter 2 was a 20-megabit HuCard. The PCE has a maximum 8-megabit addressable ROM space.
		// Therefore SF2 had a special mapper to make this work.
		private byte SF2MapperLatch;

		// when true, every mapper register write is propogated to the vtable that the CDL uses
		private bool SF2UpdateCDLMappings = false;

		private byte ReadMemorySF2(int addr)
		{
			if (addr < 0x7FFFF) // read ROM
				return RomData[addr];

			if (addr < 0xFFFFF) // read ROM
				return RomData[(addr & 0x7FFFF) + ((SF2MapperLatch + 1) * 0x80000)];

			if (addr >= 0x1F0000 && addr < 0x1F8000) // read RAM
				return Ram[addr & 0x1FFF];

			if (addr >= 0x1FE000) // hardware page.
			{
				if (addr < 0x1FE400) return VDC1.ReadVDC(addr);
				if (addr < 0x1FE800) { Cpu.PendingCycles--; return VCE.ReadVCE(addr); }
				if (addr < 0x1FEC00) return IOBuffer;
				if (addr < 0x1FF000) { IOBuffer = (byte)(Cpu.ReadTimerValue() | (IOBuffer & 0x80)); return IOBuffer; }
				if (addr >= 0x1FF000 &&
					addr < 0x1FF400) { IOBuffer = ReadInput(); return IOBuffer; }
				if ((addr & ~1) == 0x1FF400) return IOBuffer;
				if (addr == 0x1FF402) { IOBuffer = Cpu.IRQControlByte; return IOBuffer; }
				if (addr == 0x1FF403) { IOBuffer = (byte)(Cpu.ReadIrqStatus() | (IOBuffer & 0xF8)); return IOBuffer; }
			}

			Log.Error("MEM", "UNHANDLED READ: {0:X6}", addr);
			return 0xFF;
		}

		private void WriteMemorySF2(int addr, byte value)
		{
			if ((addr & 0x1FFC) == 0x1FF0)
			{
				// Set SF2 pager.
				SF2MapperLatch = (byte)(addr & 0x03);

				if (SF2UpdateCDLMappings)
				{
					CDLMappingApplyRange(Cpu.Mappings, "ROM", 0x40, 0x80000, (SF2MapperLatch + 1) * 0x80000);
				}

				return;
			}

			if (addr >= 0x1F0000 && addr < 0x1F8000) // write RAM.
				Ram[addr & 0x1FFF] = value;

			else if (addr >= 0x1FE000) // hardware page.
			{
				if (addr < 0x1FE400) VDC1.WriteVDC(addr, value);
				else if (addr < 0x1FE800) { Cpu.PendingCycles--; VCE.WriteVCE(addr, value); }
				else if (addr < 0x1FEC00) { IOBuffer = value; PSG.WritePSG((byte)addr, value, Cpu.TotalExecutedCycles); }
				else if (addr == 0x1FEC00) { IOBuffer = value; Cpu.WriteTimer(value); }
				else if (addr == 0x1FEC01) { IOBuffer = value; Cpu.WriteTimerEnable(value); }
				else if (addr >= 0x1FF000 &&
						 addr < 0x1FF400) { IOBuffer = value; WriteInput(value); }
				else if (addr == 0x1FF402) { IOBuffer = value; Cpu.WriteIrqControl(value); }
				else if (addr == 0x1FF403) { IOBuffer = value; Cpu.WriteIrqStatus(); }
				else Log.Error("MEM", "unhandled hardware write [{0:X6}] : {1:X2}", addr, value);
			}
			else
				Log.Error("MEM", "UNHANDLED WRITE: {0:X6}:{1:X2}", addr, value);
		}
	}
}