System.IO.Compression.DeflateStream.EnsureNotDisposed C# (CSharp) Method

        private void EnsureNotDisposed()
        {
            if (_stream == null)
                ThrowStreamClosedException();
        }

            public override async Task WriteAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
            {
                // Validate inputs
                Debug.Assert(buffer != _arrayPoolBuffer);
                _deflateStream.EnsureNotDisposed();
                if (count <= 0)
                {
                    return;
                }
                else if (count > buffer.Length - offset)
                {
                    // The buffer stream is either malicious or poorly implemented and returned a number of
                    // bytes larger than the buffer supplied to it.
                    throw new InvalidDataException(SR.GenericInvalidData);
                }

                // Feed the data from base stream into the decompression engine.
                _deflateStream._inflater.SetInput(buffer, offset, count);

                // While there's more decompressed data available, forward it to the buffer stream.
                while (true)
                {
                    int bytesRead = _deflateStream._inflater.Inflate(new Span <byte>(_arrayPoolBuffer));
                    if (bytesRead > 0)
                    {
                        await _destination.WriteAsync(new ReadOnlyMemory <byte>(_arrayPoolBuffer, 0, bytesRead), cancellationToken).ConfigureAwait(false);
                    }
                    else
                    {
                        break;
                    }
                }
            }