111 lines
2.2 KiB
C#
111 lines
2.2 KiB
C#
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using System.IO;
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namespace MyNes.Core;
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[BoardInfo("VRC3", 73)]
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internal class Mapper073 : Board
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{
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private bool irq_mode_8;
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private bool irq_enable;
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private bool irq_enable_on_ak;
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private int irq_reload;
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private int irq_counter;
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internal override void HardReset()
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{
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base.HardReset();
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Switch16KPRG(PRG_ROM_16KB_Mask, PRGArea.AreaC000);
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irq_mode_8 = false;
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irq_enable = false;
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irq_enable_on_ak = false;
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irq_reload = 0;
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irq_counter = 0;
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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 32768:
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irq_reload = (irq_reload & 0xFFF0) | (data & 0xF);
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break;
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case 36864:
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irq_reload = (irq_reload & 0xFF0F) | ((data & 0xF) << 4);
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break;
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case 40960:
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irq_reload = (irq_reload & 0xF0FF) | ((data & 0xF) << 8);
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break;
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case 45056:
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irq_reload = (irq_reload & 0xFFF) | ((data & 0xF) << 12);
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break;
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case 49152:
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irq_mode_8 = (data & 4) == 4;
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irq_enable = (data & 2) == 2;
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irq_enable_on_ak = (data & 1) == 1;
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if (irq_enable)
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{
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irq_counter = irq_reload;
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}
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NesEmu.IRQFlags &= -9;
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break;
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case 53248:
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irq_enable = irq_enable_on_ak;
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NesEmu.IRQFlags &= -9;
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break;
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case 61440:
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Switch16KPRG(data & 0xF, PRGArea.Area8000);
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break;
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}
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}
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internal override void OnCPUClock()
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{
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if (!irq_enable)
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{
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return;
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}
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if (irq_mode_8)
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{
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irq_counter = (irq_counter & 0xFF00) | (byte)((irq_counter & 0xFF) + 1);
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if ((byte)(irq_counter & 0xFF) == byte.MaxValue)
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{
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NesEmu.IRQFlags |= 8;
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irq_counter = (irq_counter & 0xFF00) | (irq_reload & 0xFF);
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}
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}
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else
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{
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irq_counter++;
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if (irq_counter == 65535)
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{
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NesEmu.IRQFlags |= 8;
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irq_counter = irq_reload;
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}
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}
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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(irq_mode_8);
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stream.Write(irq_enable);
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stream.Write(irq_enable_on_ak);
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stream.Write(irq_reload);
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stream.Write(irq_counter);
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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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irq_mode_8 = stream.ReadBoolean();
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irq_enable = stream.ReadBoolean();
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irq_enable_on_ak = stream.ReadBoolean();
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irq_reload = stream.ReadInt32();
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irq_counter = stream.ReadInt32();
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}
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}
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