MyNes_src/Core/MyNes.Core/Namcot106Chnl.cs

using System.IO;

namespace MyNes.Core;

internal class Namcot106Chnl
{
	private Namcot106 namcot;

	private int freqTimer;

	private int frequency;

	public int output;

	public int output_av;

	public int clocks;

	private int cycles;

	private int InstrumentLength;

	private byte InstrumentAddress;

	private int startPoint;

	private int endPoint;

	private int readPoint;

	public int volume;

	private bool freez;

	public bool Enabled { get; set; }

	public Namcot106Chnl(Namcot106 namcot)
	{
		this.namcot = namcot;
	}

	public void HardReset()
	{
	}

	private void UpdateFrequency()
	{
		if (frequency > 0)
		{
			freqTimer = 983040 * (namcot.enabledChannels + 1) / frequency;
			freez = false;
		}
		else
		{
			freez = true;
			output_av = 0;
		}
	}

	private void UpdatePlaybackParameters()
	{
		startPoint = InstrumentAddress;
		endPoint = InstrumentAddress + 4 * (8 - InstrumentLength);
		readPoint = InstrumentAddress;
	}

	public void WriteA(ref byte data)
	{
		frequency = (frequency & 0xFFFF00) | data;
		UpdateFrequency();
	}

	public void WriteB(ref byte data)
	{
		frequency = (frequency & 0xFF00FF) | (data << 8);
		UpdateFrequency();
	}

	public void WriteC(ref byte data)
	{
		frequency = (frequency & 0xFFFF) | ((data & 3) << 12);
		InstrumentLength = (data >> 2) & 7;
		UpdateFrequency();
		UpdatePlaybackParameters();
	}

	public void WriteD(ref byte data)
	{
		InstrumentAddress = data;
		UpdatePlaybackParameters();
	}

	public void WriteE(ref byte data)
	{
		volume = data & 0xF;
	}

	public void ClockSingle()
	{
		if (freez || --cycles > 0)
		{
			return;
		}
		cycles = freqTimer;
		if (readPoint >= startPoint && readPoint <= endPoint)
		{
			if (Enabled && !freez)
			{
				if ((readPoint & 1) == 0)
				{
					output_av += (namcot.EXRAM[readPoint] & 0xF) * volume;
				}
				else
				{
					output_av += ((namcot.EXRAM[readPoint] >> 4) & 0xF) * volume;
				}
			}
			readPoint++;
		}
		else
		{
			readPoint = startPoint;
		}
		clocks++;
	}

	public void SaveState(BinaryWriter stream)
	{
		stream.Write(freqTimer);
		stream.Write(frequency);
		stream.Write(output);
		stream.Write(cycles);
		stream.Write(InstrumentLength);
		stream.Write(InstrumentAddress);
		stream.Write(startPoint);
		stream.Write(endPoint);
		stream.Write(readPoint);
		stream.Write(volume);
		stream.Write(freez);
	}

	public void LoadState(BinaryReader stream)
	{
		freqTimer = stream.ReadInt32();
		frequency = stream.ReadInt32();
		output = stream.ReadByte();
		cycles = stream.ReadInt32();
		InstrumentLength = stream.ReadInt32();
		InstrumentAddress = stream.ReadByte();
		startPoint = stream.ReadInt32();
		endPoint = stream.ReadInt32();
		readPoint = stream.ReadInt32();
		volume = stream.ReadInt32();
		freez = stream.ReadBoolean();
	}
}