Mixing C and Prolog

SICStus Prolog provides a bi-directional, procedural interface for program parts written in C and Prolog. The C side of the interface defines a number of functions and macros for various operations. On the Prolog side, you have to supply declarations specifying the names and argument/value types of C functions being called as Prolog predicates. These declarations are used by the predicate load_foreign_resource/1, which performs the actual binding of C functions to Prolog predicates.

In most cases, the argument/value type declaration suffice for making the necessary conversions of data automatically as they are passed between C and Prolog. However, it is possible to declare the type of an argument to be a Prolog term, in which case the receiving function will see it as a "handle" object, called an SP_term_ref, for which access functions are provided.

The C support routines are available in a development system as well as in runtime systems. The support routines include:

• Static and dynamic linking of C code into the Prolog environment.
• Automatic conversion between Prolog terms and C data with foreign/[2,3] declarations.
• Functions for accessing and creating Prolog terms, and for creating and manipulating SP_term_refs.
• The Prolog system may call C predicates which may call Prolog back without limits on recursion. Predicates that call C may be defined dynamically from C.
• Support for creating stand-alone executables.
• Support for creating user defined Prolog streams.
• Functions to read and write on Prolog streams from C.
• Functions to install interrupt handlers that can safely call Prolog.
• Functions for manipulating mutual exclusion locks.
• User hooks that can be used to perform user defined actions on a number of occasions e.g. before reading a character from the standard input stream, upon reinitialization, etc.

• Notes:
• Calling C:
• Support:
• Calling Prolog:
• SICStus Streams:
• Hooks:
• Stand-alone Executables:
• Mixing Examples: