165 lines
3.3 KiB
C#
165 lines
3.3 KiB
C#
using BizHawk.Common;
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namespace BizHawk.Emulation.Cores.Nintendo.NES
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{
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public sealed class Mapper246 : NES.NESBoardBase
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{
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/*
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Here are Disch's original notes:
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========================
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= Mapper 246 =
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========================
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Example Game:
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--------------------------
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Fong Shen Bang - Zhu Lu Zhi Zhan
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Notes:
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--------------------------
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Regs lie at $6000-67FF, but SRAM exists at $6800-7FFF.
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Don't know if there's only 6k of SRAM, or if there's 8k, but the first 2k is inaccessable. I find the latter
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more likely.
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Registers:
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---------------------------
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Range,Mask: $6000-67FF, $6007
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$6000-6003: PRG Regs
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$6004-6007: CHR Regs
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CHR Setup:
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---------------------------
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$0000 $0400 $0800 $0C00 $1000 $1400 $1800 $1C00
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+---------------+---------------+---------------+---------------+
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| $6004 | $6005 | $6006 | $6007 |
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+---------------+---------------+---------------+---------------+
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PRG Setup:
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---------------------------
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$8000 $A000 $C000 $E000
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+-------+-------+-------+-------+
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| $6000 | $6001 | $6002 | $6003 |
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+-------+-------+-------+-------+
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Powerup/Reset:
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---------------------------
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$6003 set to $FF on powerup (and probably reset, but not sure).
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*/
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int prg_bank_mask_8k;
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ByteBuffer prg_banks_8k = new ByteBuffer(4);
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int chr_bank_mask_2k;
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ByteBuffer chr_banks_2k = new ByteBuffer(4);
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public override bool Configure(NES.EDetectionOrigin origin)
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{
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switch (Cart.board_type)
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{
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case "MAPPER246":
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break;
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default:
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return false;
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}
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prg_bank_mask_8k = (Cart.prg_size / 8) - 1;
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chr_bank_mask_2k = (Cart.chr_size / 2) - 1;
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prg_banks_8k[3] = 0xFF;
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SetMirrorType(EMirrorType.Horizontal);
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SyncMap();
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return true;
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}
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void SyncMap()
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{
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ApplyMemoryMapMask(prg_bank_mask_8k, prg_banks_8k);
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ApplyMemoryMapMask(chr_bank_mask_2k, chr_banks_2k);
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}
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public override void Dispose()
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{
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prg_banks_8k.Dispose();
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chr_banks_2k.Dispose();
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base.Dispose();
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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("prg_banks_8k", ref prg_banks_8k);
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ser.Sync("chr_banks_2k", ref chr_banks_2k);
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}
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public override void WriteWRAM(int addr, byte value)
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{
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if (addr < 0x0800)
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{
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addr &= 0x0007;
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switch (addr)
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{
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case 0:
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prg_banks_8k[0] = value;
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break;
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case 1:
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prg_banks_8k[1] = value;
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break;
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case 2:
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prg_banks_8k[2] = value;
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break;
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case 3:
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prg_banks_8k[3] = value;
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break;
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case 4:
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chr_banks_2k[0] = value;
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break;
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case 5:
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chr_banks_2k[1] = value;
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break;
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case 6:
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chr_banks_2k[2] = value;
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break;
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case 7:
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chr_banks_2k[3] = value;
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break;
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}
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SyncMap();
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}
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else
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{
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base.WriteWRAM(addr, value);
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}
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}
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public override byte ReadPPU(int addr)
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{
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if (addr < 0x2000)
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{
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addr = ApplyMemoryMap(11, chr_banks_2k, addr);
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return base.ReadPPUChr(addr);
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}
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else
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{
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return base.ReadPPU(addr);
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}
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}
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public override byte ReadPRG(int addr)
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{
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addr = ApplyMemoryMap(13, prg_banks_8k, addr);
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return ROM[addr];
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}
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}
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}
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