Wireshark Wiki provides toyasn1 sample code to demonstrate how to build an ASN.1-based dissector as a plugin. But this file has not been updated since 2010, so it can not be used in Wireshark 2.0 or above.
This plugin is the update version of toyasn1 to support the latest version of Wireshark. This plugin is tested with Wireshark 3.1 on Windows.