97 lines
1.9 KiB
C#
97 lines
1.9 KiB
C#
using BizHawk.Common;
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namespace BizHawk.Emulation.Cores.Atari.Atari2600
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{
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/*
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EF (no name?)
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-----
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This is a fairly simple method that allows for up to 64K of ROM, using 16 4K banks.
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It works similar to F8, F6, etc. Only the addresses to perform the switch is
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1FE0-1FEF. Accessing one of these will select the desired bank. 1FE0 = bank 0,
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1FE1 = bank 1, etc.
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*/
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internal class mEF : MapperBase
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{
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private int _toggle;
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public mEF(Atari2600 core) : base(core)
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{
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}
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public override void SyncState(Serializer ser)
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{
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base.SyncState(ser);
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ser.Sync("toggle", ref _toggle);
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}
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public override void HardReset()
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{
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_toggle = 0;
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base.HardReset();
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}
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public override byte ReadMemory(ushort addr) => ReadMem(addr, false);
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public override byte PeekMemory(ushort addr) => ReadMem(addr, true);
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public override void WriteMemory(ushort addr, byte value)
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=> WriteMem(addr, value, false);
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public override void PokeMemory(ushort addr, byte value)
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=> WriteMem(addr, value, true);
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private byte ReadMem(ushort addr, bool peek)
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{
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if (!peek)
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{
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Address(addr);
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}
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if (addr < 0x1000)
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{
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return base.ReadMemory(addr);
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}
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return Core.Rom[(_toggle << 12) + (addr & 0xFFF)];
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}
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private void WriteMem(ushort addr, byte value, bool poke)
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{
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if (!poke)
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{
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Address(addr);
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}
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if (addr < 0x1000)
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{
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base.WriteMemory(addr, value);
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}
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}
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private void Address(ushort addr)
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{
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_toggle = addr switch
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{
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0x1FE0 => 0,
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0x1FE1 => 1,
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0x1FE2 => 2,
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0x1FE3 => 3,
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0x1FE4 => 4,
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0x1FE5 => 5,
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0x1FE6 => 6,
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0x1FE7 => 7,
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0x1FE8 => 8,
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0x1FE9 => 9,
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0x1FEA => 10,
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0x1FEB => 11,
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0x1FEC => 12,
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0x1FED => 13,
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0x1FEE => 14,
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0x1FEF => 15,
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_ => _toggle
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};
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}
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}
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}
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