90 lines
3.2 KiB
C#
90 lines
3.2 KiB
C#
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namespace BizHawk.Emulation.Consoles.TurboGrafx
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{
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public partial class PCEngine
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{
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// Street Fighter 2 was a 20-megabit HuCard. The PCE has a maximum 8-megabit addressable ROM space.
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// Therefore SF2 had a special mapper to make this work.
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// TODO: need to update SF2 mapper to reflect updates made to the primary mapper
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// (ie, the IOBuffer)
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// However, I believe more fixes will be made in the future, and SF2 works, so this is not
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// currently a priority.
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private byte SF2MapperLatch;
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private byte ReadMemorySF2(ushort addr)
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{
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int page = Cpu.MPR[addr >> 13];
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ushort addr13 = (ushort)(addr & 0x1FFF);
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if (page < 0x40)
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{
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// read rom.
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return RomData[(page % RomPages << 13) | (addr13)];
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}
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if (page < 0x80)
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{
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// read rom with extended SF2 mapper.
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return RomData[(((page << 13) | addr13) & 0x7FFFF) + ((SF2MapperLatch + 1)*0x80000)];
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}
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if (page >= 0xF8 && page <= 0xFB)
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{
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// read RAM.
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return Ram[((page-0xF8) << 13) | addr13];
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}
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if (page == 0xFF)
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{
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// hardware page.
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if (addr13 < 0x400) return VDC1.ReadVDC(addr13 & 0x03);
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if (addr13 < 0x800) return VCE.ReadVCE((addr13 & 0x07));
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if ((addr13 & ~1) == 0x0C00) return Cpu.TimerValue;
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if (addr13 >= 0x1000 && addr13 < 0x1400) return ReadInput();
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if (addr13 == 0x1402) return Cpu.IRQControlByte;
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if (addr13 == 0x1403) return Cpu.ReadIrqStatus();
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}
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Log.Error("MEM", "UNHANDLED READ: [{0:X2}] {1:X4}", page, addr13);
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return 0xFF;
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}
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private void WriteMemorySF2(ushort addr, byte value)
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{
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int page = Cpu.MPR[addr >> 13];
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ushort addr13 = (ushort)(addr & 0x1FFF);
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if ((addr & 0x1FFC) == 0x1FF0)
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{
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// Set SF2 pager.
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SF2MapperLatch = (byte) (addr & 0x03);
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return;
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}
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if (page >= 0xF8 && page <= 0xFB)
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{
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// write RAM.
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Ram[addr13] = value;
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}
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if (page == 0xFF)
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{
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// hardware page.
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if (addr13 < 0x400)
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VDC1.WriteVDC(addr13 & 3, value);
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else if (addr13 < 0x800)
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VCE.WriteVCE(addr13 & 7, value);
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else if (addr13 < 0x80A)
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PSG.WritePSG(addr13, value, Cpu.TotalExecutedCycles);
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else if (addr13 == 0x0C00)
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Cpu.WriteTimer(value);
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else if (addr13 == 0x0C01)
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Cpu.WriteTimerEnable(value);
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else if (addr13 >= 0x1000 && addr13 < 0x1400)
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WriteInput(value);
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else if (addr13 == 0x1402)
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Cpu.WriteIrqControl(value);
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else if (addr13 == 0x1403)
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Cpu.WriteIrqStatus();
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}
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}
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}
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}
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