Miles Sound System SDK 7.2a

AIL_register_event_callback

The function AIL_register_event_callback registers an application function to be called immediately prior to processing each XMIDI or MIDI Channel Voice message event associated with a given driver.

AILEVENTCB AIL_register_event_callback(
  HMDIDRIVER mdi,
  AILEVENTCB callback
);

In Parameters

mdi: indicates the driver whose XMIDI and MIDI events are to be trapped by the callback function.
callback: should be set to the address of an application function prototyped as an AILEVENTCB callback.

Returns

The address of the previously-installed event trap function handler.

Discussion

Most MSS functions can be safely invoked from within callback functions. Exceptions include driver-installation or driver-shutdown functions and any other functions which may perform DOS or BIOS calls, such as AIL_init_sequence. These exceptions are noted in the descriptions of the functions involved. If in doubt about whether a particular action may safely be performed from within a callback function, contact RAD Game Tools for assistance.

Notwithstanding the above, it is recommended that application programmers refrain from calling other MSS XMIDI functions from within a MIDI event trap except when absolutely necessary, and only after carefully examining AILXMIDI.C's source code to guard against potentially undesirable side-effects. For example, an explicit call to AIL_send_channel_voice_message from within a MIDI event trap callback function may result in a reentrant call to the MIDI event trap function.

This function is intended primarily for use in tool and diagnostic program development, and to provide a way for the application to implement its own MIDI/XMIDI interpreter (for example, a software-based "wavetable synthesizer" such as AILXDIG.C).

Group: XMIDI Services
Related Functions: AILEVENTCB, AIL_init_sequence, AIL_register_beat_callback, AIL_register_prefix_callback, AIL_register_sequence_callback, AIL_register_timbre_callback, AIL_register_trigger_callback, AIL_send_channel_voice_message
Related Basic Types: HMDIDRIVER
Related FAQs: What's the deal with callbacks - are they threads, interrupts, system timers, or what?