hal_export_funct(3hal)

💖 hal_export_funct 💖

okay bestie, welcome to the hal_export_funct(3hal) page — yes that's the manual name, it lives in section 3hal, and it's literally the glow-up your realtime function needs to get noticed by the whole system ✨

✨ NAME ✨

hal_export_funct — create a realtime function callable from a thread 🧵💅

🎀 SYNTAX 🎀

typedef void(*hal_funct_t)(void * arg, long period)

int hal_export_funct(const char *name, hal_funct_t funct, void *arg, int
       uses_fp, int reentrant, int comp_id)

that's the whole vibe, no cap 🦋

🌸 ARGUMENTS 🌸

• name — the name of the function. like, its name-name. what you're gonna call it 👑
• funct — the pointer to the function 🫶
• arg — the argument that gets passed as the first parameter of funct
• uses_fp — nonzero if the function does floating-point operations, and yes that includes assigning floating point values with "=" 😭 don't skip that part, it counts
• reentrant — if reentrant is non-zero, the function may be preempted and called again before the first call even finishes 💀 otherwise? it may only be added to one thread. one. single. thread. 🚫
• comp_id — a HAL component identifier, and you get that from an earlier call to hal_init 🌈

💜 DESCRIPTION 💜

hal_export_funct makes a realtime function that a component provides available to the system. that's it, that's the whole serve 💅 then a later call to hal_add_funct_to_thread can be used to schedule when the function actually runs, as the system needs it.

so when this function gets placed on a HAL thread, and HAL threads are started, funct gets called over and over again with two arguments: void *arg is the exact same value you gave to hal_export_funct, and long period is the interval between calls, measured in nanoseconds ⏱️

and listen — each call to the function should do a small amount of work and return. small. tiny. a lil snack, not a whole feast 🙈

⭐ RETURN VALUE ⭐

Returns a HAL status code ✨

🔥 SEE ALSO 🔥

• hal_create_thread(3hal)
• hal_add_funct_to_thread(3hal)

and that's the page bestie 🎀 big shoutout to the LinuxCNC Documentation crew — this one's dated 2006-10-12, so it's been iconic for a minute 👑 mwah, go schedule something 💖