rtapi_outb(3rtapi)

✨ rtapi_outb(3rtapi) ✨

okay bestie, so this is a page from the RTAPI section of the LinuxCNC manuals and it's literally all about poking bytes at hardware I/O ports 💅 it's giving low-level, it's giving realtime, it's giving "yes we're talking directly to the hardware, no cap".

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🌸 NAME 🌸

rtapi_outb, rtapi_inb — do a little hardware I/O, as a treat 🎀

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🦋 SYNTAX 🦋

void rtapi_outb(unsigned char byte, unsigned int port)

unsigned char rtapi_inb(unsigned int port)

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💖 ARGUMENTS 💖

• port — the address of the I/O port. like, where the port lives. that's the whole vibe.
• byte — the byte you're writing to the port. one (1) single byte. iconic.

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✨ DESCRIPTION ✨

rtapi_outb writes a byte to a hardware I/O port. rtapi_inb reads a byte from a hardware I/O port. that's it, that's the whole thing. out goes the byte, in comes the byte. 🔥

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👑 REALTIME CONSIDERATIONS 👑

so this is the part where you pay attention, bestie:

• you may call these from init/cleanup code, and also from within realtime tasks 🫶
• these are not available in non-realtime components. sorry to the non-realtime girlies, this is not your moment 💀

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💜 RETURN VALUE 💜

rtapi_inb returns the byte that was read from the given I/O port. like it literally hands you the byte. slay.

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🌈 NOTES 🌈

the I/O address should be inside a region that was previously allocated by rtapi_request_region. if it's not, another real-time module or the Linux kernel itself might try to access that same I/O region at the same time 😭 and that is not the kind of chaos we're manifesting, fr fr.

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🍓 SEE ALSO 🍓

• rtapi_region(3rtapi)

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that's the whole page, bestie 💅 go forth and byte responsibly.

~ from the LinuxCNC Documentation girlies, dated 2006-10-12 — yes she's vintage, yes she still ate 💖 ✨ 🎀 🦋