OrmSimple is a ORM for FirebirdSql (http://firebirdsql.org), based on Demis Bellot's ServiceStack.OrmLite (http://servicestack.net)
For usage samples see :
https://github.com/aicl/ormsimple/tree/master/src/TestSimpleFirebird01
https://github.com/aicl/ormsimple/tree/master/src/TestSimpleFirebird02
https://github.com/aicl/ormsimple/tree/master/src/TestSimpleFirebird03
https://github.com/aicl/ormsimple/tree/master/src/TestSimpleFirebirdProcedures
If you already have a firebird database you can use ClassWriter to generate CSharp code for each table and procedure. See https://github.com/aicl/ormsimple/tree/master/src/Maquinaria
To run samples you must use employee.fdb from https://github.com/aicl/ormsimple/tree/master/fbdata