Ultima.FileIndex.FileIndex C# (CSharp) Method

        public FileIndex(string idxFile, string mulFile, int file)
        {
            string idxPath = null;
            MulPath = null;
            if (Files.MulPath == null)
                Files.LoadMulPath();
            if (Files.MulPath.Count > 0)
            {
                idxPath = Files.MulPath[idxFile.ToLower()];
                MulPath = Files.MulPath[mulFile.ToLower()];
                if (String.IsNullOrEmpty(idxPath))
                    idxPath = null;
                else
                {
                    if (String.IsNullOrEmpty(Path.GetDirectoryName(idxPath)))
                        idxPath = Path.Combine(Files.RootDir, idxPath);
                    if (!File.Exists(idxPath))
                        idxPath = null;
                }
                if (String.IsNullOrEmpty(MulPath))
                    MulPath = null;
                else
                {
                    if (String.IsNullOrEmpty(Path.GetDirectoryName(MulPath)))
                        MulPath = Path.Combine(Files.RootDir, MulPath);
                    if (!File.Exists(MulPath))
                        MulPath = null;
                }
            }

            if ((idxPath != null) && (MulPath != null))
            {
                using (FileStream index = new FileStream(idxPath, FileMode.Open, FileAccess.Read, FileShare.Read))
                {
                    Stream = new FileStream(MulPath, FileMode.Open, FileAccess.Read, FileShare.Read);
                    int count = (int)(index.Length / 12);
                    IdxLength = index.Length;
                    Index = new Entry3D[count];
                    GCHandle gc = GCHandle.Alloc(Index, GCHandleType.Pinned);
                    byte[] buffer = new byte[index.Length];
                    index.Read(buffer, 0, (int)index.Length);
                    Marshal.Copy(buffer, 0, gc.AddrOfPinnedObject(), (int)index.Length);
                    gc.Free();
                }
            }
            else
            {
                Stream = null;
                Index = new Entry3D[1];
                return;
            }
            Entry5D[] patches = Verdata.Patches;

            if (file > -1)
            {
                for (int i = 0; i < patches.Length; ++i)
                {
                    Entry5D patch = patches[i];

                    if (patch.file == file && patch.index >= 0 && patch.index < Index.Length)
                    {
                        Index[patch.index].lookup = patch.lookup;
                        Index[patch.index].length = patch.length | (1 << 31);
                        Index[patch.index].extra = patch.extra;
                    }
                }
            }
        }