another data view

TanksServer/ServicePointDisplay/FixedSizeBitRowView.cs

@@ -0,0 +1,82 @@
+using System.Collections;
+
+namespace TanksServer.ServicePointDisplay;
+
+internal sealed class FixedSizeBitRowView(Memory<byte> data) : IList<bool>
+{
+    public int Count => data.Length * 8;
+    public bool IsReadOnly => false;
+
+    IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
+
+    public IEnumerator<bool> GetEnumerator()
+    {
+        return Enumerable().GetEnumerator();
+
+        IEnumerable<bool> Enumerable()
+        {
+            for (var i = 0; i < Count; i++)
+                yield return this[i];
+        }
+    }
+
+    public void Clear()
+    {
+        var span = data.Span;
+        for (var i = 0; i < data.Length; i++)
+            span[i] = 0;
+    }
+
+    public void CopyTo(bool[] array, int arrayIndex)
+    {
+        for (var i = 0; i < Count && i + arrayIndex < array.Length; i++)
+            array[i + arrayIndex] = this[i];
+    }
+
+    private (int byteIndex, int bitInByteIndex) GetIndexes(int bitIndex)
+    {
+        var byteIndex = bitIndex / 8;
+        var bitInByteIndex = 7 - bitIndex % 8;
+        if (byteIndex >= data.Length)
+        {
+            throw new ArgumentOutOfRangeException(nameof(bitIndex), 
+                $"accessing this bit field at position {bitIndex} would result in an access to byte " +
+                $"{byteIndex} but byte length is {data.Length}");
+        }
+
+        return (byteIndex, bitInByteIndex);
+    }
+
+    public bool this[int bitIndex]
+    {
+        get
+        {
+            var (byteIndex, bitInByteIndex) = GetIndexes(bitIndex);
+            var bitInByteMask = (byte)(1 << bitInByteIndex);
+            return (data.Span[byteIndex] & bitInByteMask) != 0;
+        }
+
+        set
+        {
+            var (byteIndex, bitInByteIndex) = GetIndexes(bitIndex);
+            var bitInByteMask = (byte)(1 << bitInByteIndex);
+
+            if (value)
+            {
+                data.Span[byteIndex] |= bitInByteMask;
+            }
+            else
+            {
+                var withoutBitMask = (byte)(ushort.MaxValue ^ bitInByteMask);
+                data.Span[byteIndex] &= withoutBitMask;
+            }
+        }
+    }
+
+    public void Add(bool item) => throw new NotSupportedException();
+    public bool Contains(bool item) => throw new NotSupportedException();
+    public bool Remove(bool item) => throw new NotSupportedException();
+    public int IndexOf(bool item) => throw new NotSupportedException();
+    public void Insert(int index, bool item) => throw new NotSupportedException();
+    public void RemoveAt(int index) => throw new NotSupportedException();
+}