[Blb3] Fixed some blocks parsing, some refactoring

AssetStudio/OffsetStream.cs

@@ -79,61 +79,16 @@ namespace AssetStudio
             }
             else
             {
-                using var reader = new FileReader(path, this, true);
-
-                var readSignature = reader.FileType;
-                var signature = "";
-
-                if (readSignature == FileType.BundleFile ||
-                    readSignature == FileType.MhyFile ||
-                    readSignature == FileType.Blb3File)
+                while (Remaining > 0)
                 {
-                    switch (reader.FileType)
+                    Offset = AbsolutePosition;
+                    yield return AbsolutePosition;
+                    if (Offset == AbsolutePosition)
                     {
-                        case FileType.BundleFile:
-                            signature = "UnityFS\x00";
-                            break;
-                        case FileType.MhyFile:
-                            signature = "mhy0";
-                            break;
-                        case FileType.Blb3File:
-                            signature = "Blb\x03";
-                            break;
-                    }
-
-                    Logger.Verbose($"Parsed signature: {signature}");
-
-                    var signatureBytes = Encoding.UTF8.GetBytes(signature);
-                    var buffer = ArrayPool<byte>.Shared.Rent((int)reader.Length);
-                    while (Remaining > 0)
-                    {
-                        var index = 0;
-                        var absOffset = AbsolutePosition;
-                        var read = Read(buffer);
-                        while (index < read)
-                        {
-                            index = buffer.AsSpan(0, read).Search(signatureBytes, index);
-                            if (index == -1) break;
-                            var offset = absOffset + index;
-                            Offset = offset;
-                            yield return offset;
-                            index++;
-                        }
-                    }
-                    ArrayPool<byte>.Shared.Return(buffer);
-                } else
-                {
-                    while (Remaining > 0)
-                    {
-                        Offset = AbsolutePosition;
-                        yield return AbsolutePosition;
-                        if (Offset == AbsolutePosition)
-                        {
-                            break;
-                        }
+                        break;
                     }
                 }
             }
         }
     }
-}
+}