NVorbis.StreamReadBuffer.EnsureAvailable C# (CSharp) Method

        int EnsureAvailable(long offset, ref int count, bool isRecursion)
        {
            // simple... if we're inside the buffer, just return the offset (FAST PATH)
            if (offset >= _baseOffset && offset + count < _baseOffset + _end)
            {
                return (int)(offset - _baseOffset);
            }

            // not so simple... we're outside the buffer somehow...

            // let's make sure the request makes sense
            if (count > _maxSize)
            {
                throw new InvalidOperationException("Not enough room in the buffer!  Increase the maximum size and try again.");
            }

            // make sure we always bump the version counter when a change is made to the data in the "live" buffer
            ++_versionCounter;

            // can we satisfy the request with a saved buffer?
            if (!isRecursion)
            {
                for (int i = 0; i < _savedBuffers.Count; i++)
                {
                    var tempS = _savedBuffers[i].BaseOffset - offset;
                    if ((tempS < 0 && _savedBuffers[i].End + tempS > 0) || (tempS > 0 && count - tempS > 0))
                    {
                        SwapBuffers(_savedBuffers[i]);
                        return EnsureAvailable(offset, ref count, true);
                    }
                }
            }

            // look for buffers we need to drop due to age...
            while (_savedBuffers.Count > 0 && _savedBuffers[0].VersionSaved + 25 < _versionCounter)
            {
                _savedBuffers[0].Buffer = null;
                _savedBuffers.RemoveAt(0);
            }

            // if we have to seek back, we're doomed...
            if (offset < _baseOffset && !_wrapper.Source.CanSeek)
            {
                throw new InvalidOperationException("Cannot seek before buffer on forward-only streams!");
            }

            // figure up the new buffer parameters...
            int readStart;
            int readEnd;
            CalcBuffer(offset, count, out readStart, out readEnd);

            // fill the buffer...
            // if we did a reverse seek, there will be data still in end of the buffer...  Make sure to fill everything between
            count = FillBuffer(offset, count, readStart, readEnd);

            return (int)(offset - _baseOffset);
        }