using System.Runtime.CompilerServices;

[MethodImpl(MethodImplOptions.AggressiveInlining)]
unsafe public static ref T As<T>(this Span<byte> span) where T : struct
{
  fixed (void* p = &span[0])
    return ref Unsafe.AsRef<T>(p);
}

[MethodImpl(MethodImplOptions.AggressiveInlining)]
unsafe public static ref readonly T As<T>(this ReadOnlySpan<byte> span) where T : struct
{
  fixed (void* p = &span[0])
    return ref Unsafe.AsRef<T>(p);
}

// Usage:
// Span<byte> span = ...
// var data = ref span.As<MyDataStruct>();
// data.MyValue = 22; // Will modify span's memory directly