100 lines
1.9 KiB
C#
100 lines
1.9 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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namespace BizHawk.Emulation.Consoles.Nintendo
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{
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class Mapper231 : 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 231 =
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========================
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Example Game:
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--------------------------
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20-in-1
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Registers:
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---------------------------
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$8000-FFFF: A~[.... .... M.LP PPP.]
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M = Mirroring (0=Vert, 1=Horz)
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L = Low bit of PRG
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P = High bits of PRG
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PRG Setup:
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---------------------------
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Note that 'L' and 'P' bits make up the PRG reg, and the 'L' is the low bit.
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$8000 $A000 $C000 $E000
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+---------------+---------------+
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| $8000 AND $1E | $8000 |
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+---------------+---------------+
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*/
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public int prg_reg;
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public bool low;
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public int prg_bank_mask_16k;
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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 "MAPPER231":
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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_16k = Cart.prg_size / 16 - 1;
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return true;
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}
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public override void SyncState(Serializer ser)
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{
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ser.Sync("prg_reg", ref prg_reg);
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base.SyncState(ser);
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}
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public override void WritePRG(int addr, byte value)
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{
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if (addr.Bit(7))
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{
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SetMirrorType(EMirrorType.Horizontal);
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}
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else
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{
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SetMirrorType(EMirrorType.Vertical);
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}
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int prg_reg_P = (addr >> 1) & 0xF;
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int prg_reg_L = (addr >> 5) & 1;
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prg_reg = (prg_reg_P<<1) | prg_reg_L;
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prg_reg &= prg_bank_mask_16k;
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}
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public override byte ReadPRG(int addr)
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{
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if (low)
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{
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int bank = prg_reg & 0x1E;
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return ROM[(bank << 14) + addr];
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}
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else
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{
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int bank = prg_reg;
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return ROM[(bank << 14) + addr - 0x4000];
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}
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}
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}
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}
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