internal MsfDirectory(PdbReader reader, PdbFileHeader head, BitAccess bits)
        {
            bits.MinCapacity(head.directorySize);
            int pages = reader.PagesFromSize(head.directorySize);

            // 0..n in page of directory pages.
            reader.Seek(head.directoryRoot, 0);
            bits.FillBuffer(reader.reader, pages * 4);

            DataStream stream = new DataStream(head.directorySize, bits, pages);

            bits.MinCapacity(head.directorySize);
            stream.Read(reader, bits);

            // 0..3 in directory pages
            int count;

            bits.ReadInt32(out count);

            // 4..n
            int[] sizes = new int[count];
            bits.ReadInt32(sizes);

            // n..m
            streams = new DataStream[count];
            for (int i = 0; i < count; i++)
            {
                if (sizes[i] <= 0)
                {
                    streams[i] = new DataStream();
                }
                else
                {
                    streams[i] = new DataStream(sizes[i], bits,
                                                reader.PagesFromSize(sizes[i]));
                }
            }
        }