FixedSizeBuffers

A collection of fixed-size structs which can be treated as Spans. A replacement for stackalloc (or fixed-size buffers), but these buffers can contain reference types (and can't be dynamically sized).

void Copy(TextReader reader, TextWriter writer)
{
    // Allocate 2kB on the stack
    var buffer = new FixedSizeBuffer1024<char>();
    var span = buffer.AsSpan();

    var count = -1;
    while (count != 0)
    {
        count = reader.Read(span);
        writer.Write(span.Slice(count));
    }
    
    buffer.Dispose();
}

Buffers are provided in powers-of-two lengths, from 2 to 8192.

I hope you know what you're doing

Use of this library is potentially unsafe. When calling AsSpan or AsReadOnlySpan, you must make sure the Span doesn't outlive the FixedSizeBuffer. Basically, don't return the Span.

Span<int> Bad()
{
    var buffer = new FixedSizeBuffer4<int>();
    return buffer.AsSpan();  // Don't do this
}

You can safely pass around spans into buffers which live on the heap — but if you're doing that you might as well use an array.