private static unsafe void ReplacePlusWithSpaceCore(Span <char> buffer, IntPtr state)
        {
            fixed(char *ptr = &MemoryMarshal.GetReference(buffer))
            {
                var input  = (ushort *)state.ToPointer();
                var output = (ushort *)ptr;

                var i = (nint)0;
                var n = (nint)(uint)buffer.Length;

                if (Vector256.IsHardwareAccelerated && n >= Vector256 <ushort> .Count)
                {
                    var vecPlus  = Vector256.Create((ushort)'+');
                    var vecSpace = Vector256.Create((ushort)' ');

                    do
                    {
                        var vec  = Vector256.Load(input + i);
                        var mask = Vector256.Equals(vec, vecPlus);
                        var res  = Vector256.ConditionalSelect(mask, vecSpace, vec);
                        res.Store(output + i);
                        i += Vector256 <ushort> .Count;
                    } while (i <= n - Vector256 <ushort> .Count);
                }

                if (Vector128.IsHardwareAccelerated && n - i >= Vector128 <ushort> .Count)
                {
                    var vecPlus  = Vector128.Create((ushort)'+');
                    var vecSpace = Vector128.Create((ushort)' ');

                    do
                    {
                        var vec  = Vector128.Load(input + i);
                        var mask = Vector128.Equals(vec, vecPlus);
                        var res  = Vector128.ConditionalSelect(mask, vecSpace, vec);
                        res.Store(output + i);
                        i += Vector128 <ushort> .Count;
                    } while (i <= n - Vector128 <ushort> .Count);
                }

                for (; i < n; ++i)
                {
                    if (input[i] != '+')
                    {
                        output[i] = input[i];
                    }
                    else
                    {
                        output[i] = ' ';
                    }
                }
            }
        }