Exporting the Initialization and Termination Functions

Exporting the Initialization and Termination Functions

A device driver must export the Frame Scheduler interface functions to make them known to the Frame Scheduler. This call, which occurs during the device driver's own initialization, also makes the driver known as a source of time-base interrupts:

frs_driver_export( int frs_driver_id,
                  void (*frs_func_set)(intrgroup_t*),
                  void (*frs_func_clear)(void));

A typical call resembles the code in Example 7-8.

The parameter frs_driver_id is the driver's identification number. A real-time program specifies the same number to frs_create_master() in order to select this driver as the source of interrupts. The identifier is an integer between 0 and 7. Different drivers in the same system must use different identifiers.

Example 7-8 : Exporting Device Driver Entry Points

/*
** Function called by the example driver to export
** its Frame Scheduler interface functions.
*/
frs_driver_export(3, example_frs_func_set, example_frs_func_clear);