Substation/State.cs

using System.Collections.Concurrent;

namespace Substation;

public class State
{
    public readonly object Lock = new();

    public bool DirtyA, DirtyB;
    public int DesiredA, DesiredB;

    public byte[]? LoopFreqA, LoopIntA;
    public byte[]? LoopFreqB, LoopIntB;

    public readonly ConcurrentQueue<WaveFrame> StreamA = new();
    public readonly ConcurrentQueue<WaveFrame> StreamB = new();

    public int ActualA, ActualB;
    public int LastSentA, LastSentB;

    public int MaxStrength = 200;
    public LimitMode LimitMode = LimitMode.Clamp;

    public void SetLimit(int max, LimitMode mode)
    {
        lock (Lock)
        {
            MaxStrength = Math.Clamp(max, 0, 200);
            LimitMode = mode;
            DirtyA = true;
            DirtyB = true;
        }
    }

    public bool IsSignaling
    {
        get
        {
            lock (Lock)
            {
                bool hasPattern = LoopFreqA != null || LoopFreqB != null
                                  || !StreamA.IsEmpty || !StreamB.IsEmpty;
                bool hasStrength = DesiredA > 0 || DesiredB > 0;
                return hasPattern && hasStrength;
            }
        }
    }

    public void SetStrength(char ch, int value)
    {
        lock (Lock)
        {
            var clamped = Math.Clamp(value, 0, 200);
            if (ch == 'A') { DesiredA = clamped; DirtyA = true; }
            else           { DesiredB = clamped; DirtyB = true; }
        }
    }

    public void SetLoop(char ch, byte[] freq, byte[] intensity)
    {
        lock (Lock)
        {
            if (ch == 'A') { LoopFreqA = freq; LoopIntA = intensity; }
            else           { LoopFreqB = freq; LoopIntB = intensity; }
        }
    }

    public void EnqueueStream(char ch, IEnumerable<WaveFrame> frames)
    {
        var queue = ch == 'A' ? StreamA : StreamB;
        foreach (var f in frames)
            queue.Enqueue(f);
    }

    public void Stop(char ch)
    {
        lock (Lock)
        {
            if (ch == 'A') { LoopFreqA = null; LoopIntA = null; }
            else           { LoopFreqB = null; LoopIntB = null; }
        }
        var queue = ch == 'A' ? StreamA : StreamB;
        while (queue.TryDequeue(out _)) { }
    }

    public (StrengthMode modeA, byte valA, StrengthMode modeB, byte valB,
            byte[] freqA, byte[] intA, byte[] freqB, byte[] intB)
        ConsumeTick()
    {
        lock (Lock)
        {
            var modeA = DirtyA ? StrengthMode.Abs : StrengthMode.None;
            var modeB = DirtyB ? StrengthMode.Abs : StrengthMode.None;

            var limit = MaxStrength;
            var limMode = LimitMode;
            byte ApplyLimit(int desired) =>
                limMode == LimitMode.Scale
                    ? (byte)(desired * limit / 200)
                    : (byte)Math.Clamp(desired, 0, limit);
            var valA  = ApplyLimit(DesiredA);
            var valB  = ApplyLimit(DesiredB);
            LastSentA = valA;
            LastSentB = valB;
            DirtyA = false;
            DirtyB = false;

            var (freqA, intA) = PopWave(StreamA, LoopFreqA, LoopIntA);
            var (freqB, intB) = PopWave(StreamB, LoopFreqB, LoopIntB);

            return (modeA, valA, modeB, valB, freqA, intA, freqB, intB);
        }
    }

    static (byte[] freq, byte[] intensity) PopWave(
        ConcurrentQueue<WaveFrame> stream,
        byte[]? loopFreq, byte[]? loopInt)
    {
        if (stream.TryDequeue(out var frame))
            return (frame.Freq, frame.Intensity);

        if (loopFreq != null && loopInt != null)
            return (loopFreq, loopInt);

        return (B0.ChannelOff, B0.IntensityOff);
    }
}