117 lines
2.9 KiB
C#
117 lines
2.9 KiB
C#
using System.IO;
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namespace MyNes.Core
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{
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internal abstract class MMC2 : Board
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{
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private byte chr_reg0A;
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private byte chr_reg0B;
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private byte chr_reg1A;
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private byte chr_reg1B;
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private byte latch_a = 254;
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private byte latch_b = 254;
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internal override void HardReset()
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{
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base.HardReset();
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Switch08KPRG(PRG_ROM_08KB_Mask - 2, PRGArea.AreaA000);
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Switch08KPRG(PRG_ROM_08KB_Mask - 1, PRGArea.AreaC000);
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Switch08KPRG(PRG_ROM_08KB_Mask, PRGArea.AreaE000);
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chr_reg0B = 4;
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}
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internal override void WritePRG(ref ushort address, ref byte data)
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{
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switch (address & 0xF000)
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{
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case 40960:
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Switch08KPRG(data, PRGArea.Area8000);
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break;
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case 45056:
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chr_reg0A = data;
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if (latch_a == 253)
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{
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Switch04KCHR(chr_reg0A, CHRArea.Area0000);
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}
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break;
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case 49152:
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chr_reg0B = data;
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if (latch_a == 254)
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{
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Switch04KCHR(chr_reg0B, CHRArea.Area0000);
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}
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break;
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case 53248:
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chr_reg1A = data;
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if (latch_b == 253)
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{
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Switch04KCHR(chr_reg1A, CHRArea.Area1000);
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}
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break;
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case 57344:
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chr_reg1B = data;
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if (latch_b == 254)
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{
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Switch04KCHR(chr_reg1B, CHRArea.Area1000);
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}
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break;
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case 61440:
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Switch01KNMTFromMirroring(((data & 1) == 1) ? Mirroring.Horz : Mirroring.Vert);
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break;
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}
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}
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internal override void ReadCHR(ref ushort address, out byte data)
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{
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if ((address & 0x1FF0) == 4048 && latch_a != 253)
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{
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latch_a = 253;
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Switch04KCHR(chr_reg0A, CHRArea.Area0000);
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}
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else if ((address & 0x1FF0) == 4064 && latch_a != 254)
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{
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latch_a = 254;
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Switch04KCHR(chr_reg0B, CHRArea.Area0000);
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}
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else if ((address & 0x1FF0) == 8144 && latch_b != 253)
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{
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latch_b = 253;
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Switch04KCHR(chr_reg1A, CHRArea.Area1000);
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}
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else if ((address & 0x1FF0) == 8160 && latch_b != 254)
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{
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latch_b = 254;
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Switch04KCHR(chr_reg1B, CHRArea.Area1000);
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}
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base.ReadCHR(ref address, out data);
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}
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internal override void WriteStateData(ref BinaryWriter stream)
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{
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base.WriteStateData(ref stream);
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stream.Write(chr_reg0A);
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stream.Write(chr_reg0B);
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stream.Write(chr_reg1A);
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stream.Write(chr_reg1B);
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stream.Write(latch_a);
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stream.Write(latch_b);
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}
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internal override void ReadStateData(ref BinaryReader stream)
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{
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base.ReadStateData(ref stream);
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chr_reg0A = stream.ReadByte();
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chr_reg0B = stream.ReadByte();
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chr_reg1A = stream.ReadByte();
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chr_reg1B = stream.ReadByte();
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latch_a = stream.ReadByte();
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latch_b = stream.ReadByte();
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}
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}
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}
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