41 lines
1.6 KiB
C#
41 lines
1.6 KiB
C#
namespace BizHawk.Emulation.Consoles.Sega
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{
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public partial class SMS
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{
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// The CodeMasters mapper has 3 banks of 16kb, like the Sega mapper.
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// The differences are that the paging control addresses are different, and the first 1K of ROM is not protected.
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// Bank 0: Control Address $0000 - Maps $0000 - $3FFF
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// Bank 1: Control Address $4000 - Maps $4000 - $7FFF
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// Bank 2: Control Address $8000 - Maps $8000 - $BFFF
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// System RAM is at $C000+ as in the Sega mapper.
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byte ReadMemoryCM(ushort address)
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{
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if (address < BankSize * 1) return RomData[(RomBank0 * BankSize) + address];
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if (address < BankSize * 2) return RomData[(RomBank1 * BankSize) + (address & BankSizeMask)];
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if (address < BankSize * 3) return RomData[(RomBank2 * BankSize) + (address & BankSizeMask)];
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return SystemRam[address & RamSizeMask];
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}
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void WriteMemoryCM(ushort address, byte value)
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{
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if (address >= 0xC000)
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SystemRam[address & RamSizeMask] = value;
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else if (address == 0x0000) RomBank0 = (byte)(value % RomBanks);
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else if (address == 0x4000) RomBank1 = (byte)(value % RomBanks);
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else if (address == 0x8000) RomBank2 = (byte)(value % RomBanks);
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}
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void InitCodeMastersMapper()
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{
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Cpu.ReadMemory = ReadMemoryCM;
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Cpu.WriteMemory = WriteMemoryCM;
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WriteMemoryCM(0x0000, 0);
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WriteMemoryCM(0x4000, 1);
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WriteMemoryCM(0x8000, 2);
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}
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}
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}
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