94 lines
2.5 KiB
C#
94 lines
2.5 KiB
C#
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namespace EMU7800.Core
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{
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/// <summary>
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/// Atari 7800 SuperGame bankswitched cartridge
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/// </summary>
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public sealed class Cart78SG : Cart
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{
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//
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// Cart Format Mapping to ROM Address Space
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// Bank0: 0x00000:0x4000
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// Bank1: 0x04000:0x4000 0x4000:0x4000 Bank6
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// Bank2: 0x08000:0x4000 0x8000:0x4000 Bank0-7 (0 on startup)
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// Bank3: 0x0c000:0x4000 0xc000:0x4000 Bank7
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// Bank4: 0x10000:0x4000
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// Bank5: 0x14000:0x4000
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// Bank6: 0x18000:0x4000
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// Bank7: 0x1c000:0x4000
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//
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readonly int[] Bank = new int[4];
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readonly byte[] RAM;
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#region IDevice Members
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public override byte this[ushort addr]
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{
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get
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{
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var bankNo = addr >> 14;
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if (RAM != null && bankNo == 1)
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{
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return RAM[addr & 0x3fff];
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}
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return ROM[ (Bank[bankNo] << 14) | (addr & 0x3fff) ];
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}
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set
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{
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var bankNo = addr >> 14;
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if (bankNo == 2)
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{
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Bank[2] = value & 7;
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}
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else if (RAM != null && bankNo == 1)
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{
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RAM[addr & 0x3fff] = value;
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}
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}
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}
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#endregion
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private Cart78SG()
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{
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}
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public Cart78SG(byte[] romBytes, bool needRAM)
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{
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if (needRAM)
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{
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// This works for titles that use 8KB instead of 16KB
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RAM = new byte[0x4000];
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}
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Bank[1] = 6;
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Bank[2] = 0;
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Bank[3] = 7;
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LoadRom(romBytes, 0x20000);
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}
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#region Serialization Members
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public Cart78SG(DeserializationContext input, MachineBase m) : base(input)
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{
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var version = input.CheckVersion(1, 2);
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LoadRom(input.ReadBytes());
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Bank = input.ReadIntegers(4);
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if (version == 1)
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input.ReadInt32();
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RAM = input.ReadOptionalBytes(0x4000);
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}
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public override void GetObjectData(SerializationContext output)
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{
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base.GetObjectData(output);
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output.WriteVersion(2);
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output.Write(ROM);
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output.Write(Bank);
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output.WriteOptional(RAM);
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}
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#endregion
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}
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}
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