60 lines
1.3 KiB
C#
60 lines
1.3 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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F6 (Atari style 16K)
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-----
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This is a fairly standard 16K bankswitching method. It works like F8, except there's
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four 4K banks of ROM, selected by accessing 1FF6 through 1FF9. These sequentially
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select one of the 4 banks. i.e. 1FF6 selects bank 0, 1FF7 selects bank 1, etc.
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*/
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class mF6 : MapperBase
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{
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int toggle;
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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) return base.ReadMemory(addr);
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return core.rom[(toggle << 12) + (addr & 0xFFF)];
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}
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public override byte ReadMemory(ushort addr)
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{
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return ReadMem(addr, false);
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}
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public override byte PeekMemory(ushort addr)
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{
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return ReadMem(addr, true);
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}
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public override void WriteMemory(ushort addr, byte value)
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{
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Address(addr);
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if (addr < 0x1000) base.WriteMemory(addr, value);
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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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void Address(ushort addr)
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{
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if (addr == 0x1FF6) toggle = 0;
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if (addr == 0x1FF7) toggle = 1;
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if (addr == 0x1FF8) toggle = 2;
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if (addr == 0x1FF9) toggle = 3;
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}
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}
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}
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