midi_msg_callback(3)

💖 midi_msg_callback(3) 💖

okay bestie, welcome to midi_msg_callback(3) from the Allegro manual — yes it covers three whole functions at once because they're a little trio and they do everything together, we love a friend group. it's all about the Allegro game programming library, and it's genuinely one of the most fun little corners of it, no cap. 🎀

✨ NAME ✨

midi_msg_callback, midi_meta_callback, midi_sysex_callback — hook functions that let you intercept MIDI player events. yep, you get to be the main character standing in the middle of the MIDI stream going "hold up, let me see that." 💅 Allegro game programming library, obviously. 👑

🌈 SYNOPSIS 🌈

#include <allegro.h>

extern void (*midi_msg_callback)(int msg, int byte1, int byte2);

extern void (*midi_meta_callback)(int type, const unsigned char *data,
int length);

extern void (*midi_sysex_callback)(const unsigned char *data, int
length);

🦋 DESCRIPTION 🦋

so these are hook functions, and their whole vibe is letting you intercept MIDI player events. 🌸

if you set any of them to anything other than NULL, that routine gets called for each MIDI message, meta-event, and system exclusive data block respectively. three functions, three jobs, all slaying in their own lane. ✨

🚨 okay this part is IMPORTANT, bestie, do not skim it: these routines will execute in an interrupt handler context. that means all the code and data they use should be locked, and they must not call any operating system functions. like, at all. it's giving "you are a guest in someone else's house and the house is an interrupt." 😭

in general, you just use these routines to set some flags and then respond to them later in your mainline code. that's the move. that's the whole strategy. set the flag, bounce, deal with it later when you're back in normal context. 🫶 iconic behaviour honestly.

👀 SEE ALSO 👀

• play_midi(3)

and that's the page, bestie!! 🎀💖 written up by the Allegro girlies at version 4.4.3, dated however long ago this manual page was born, still serving midi_msg_callback(3) realness to this very day. go forth and intercept some MIDI events, but lock your data first, i'm literally begging you. 🦋✨💅