Facebook.CombinationStream.ReadAsync C# (CSharp) Method

        public async override System.Threading.Tasks.Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
        {
            int result = 0;
            int buffPostion = offset;

            while (count > 0)
            {
                int bytesRead = await _currentStream.ReadAsync(buffer, buffPostion, count, cancellationToken);
                result += bytesRead;
                buffPostion += bytesRead;
                _postion += bytesRead;

                if (bytesRead <= count)
                    count -= bytesRead;

                if (count > 0)
                {
                    if (_currentStreamIndex >= _streams.Count)
                        break;

                    _currentStream = _streams[_currentStreamIndex++];
                }
            }

            return result;
        }