antlr3-runtime man page
runtimeNavigating the C Runtime Documentation
— If you are familiar with Doxygen generated documentation, then the layout of the files, typedefs and so on will be familiar to you.
However there is also additional structure applied that helps the programmer to see how the runtime is made up.
Under the Modules menu tree you will find the entry API Classes. This section is further divided into typedefs and structs and the standard runtime supplied interface implementation methods.
The typedefs are the types that you declare in your code and which are returned by the 'constructors' such as antlr38BitFileStreamNew(). The underlying structures document the data elements of the type and what a function pointer installed in any particular slot should do.
The default implementations are the static methods within the default implementation file for a 'class', which are installed by the runtime when a default instance of one the typedefs (classes) is created.
When navigating the source code, find the typedef you want to consult and inspect the documentation for its function pointers, then look at the documentation for the default methods that implement that 'method'.
For example, under 'API Typedefs and Structs' you will find 'Base Recognizer Definition', which tells you all the methods that belong to this interface. Under 'API Implementation Functions', you will find 'Base Recognizer Implementation', which documents the actual functions that are installed to implement the class methods.
From here, the documentation should be obvious. If it is not, then you could try reading the actual source code, but please don't email the author directly, use the ANTLR Interest email group, which you should probably have signed up for if you have read this far into the C runtime documentation.