COMEDI_GET_HARDWARE_(3)

💖 COMEDI_GET_HARDWARE_(3) — the Comedi reference, bestie edition 💖

okay so we're in the Comedi reference section of the manual, and today's main character is comedi_get_hardware_buffer_size. yes she's got a long name. yes she's worth it. let's go 🦋

---

✨ NAME ✨

comedi_get_hardware_buffer_size — get size of subdevice's hardware buffer 👑

like, literally just tells you how many bytes fit in the thing. that's the whole job. and she does it flawlessly. periodt.

---

🌸 SYNOPSIS 🌸

#include <comedilib.h>

int comedi_get_hardware_buffer_size(comedi_t *device,
                                    unsigned int subdevice,
                                    enum comedi_io_direction direction);

no cap, that's the whole flex. three args, one int back. she's lowkey elegant.

---

💅 DESCRIPTION 💅

okay so this function returns the number of bytes the subdevice can hold in it's hardware buffer. and before u ask what even is a hardware buffer — it's giving "any FIFOs, etc. on the acquisition board itself which are used during streaming commands." iykyk. the board has its own lil stash and this is how big that stash is 🎀

important vibe check: this does NOT include the buffer maintained by the comedi kernel module in host memory. that's a whole different buffer, bestie, and its size may be queried by comedi_get_buffer_size. two different buffers. do not confuse them. i'm literally begging 🙈

the direction parameter of type enum comedi_io_direction should be set to:

• COMEDI_INPUT — to query the input buffer size (e.g., the buffer of an analog input subdevice)
• COMEDI_OUTPUT — to query the output buffer size (e.g., the buffer of an analog output)

pick ur fighter. in or out. no in-between, she doesn't do situationships 💜

---

⭐ RETURN VALUE ⭐

• Hardware buffer size in bytes — the slay outcome ✨
• -1 — on error 😭 (we don't talk about her)

---

🫶 AUTHORS 🫶

the icons who built this. show some respect:

• David Schleef <ds@schleef.org> — Author.
• Frank Mori Hess <fmhess@users.sourceforge.net> — Author.
• Herman Bruyninckx <Herman.Bruyninckx@mech.kuleuven.ac.be> — Author.
• Bernd Porr <tech@linux-usb-daq.co.uk> — Author.
• Ian Abbott <abbotti@mev.co.uk> — Author.
• Éric Piel <piel@delmic.com> — Author.

six whole legends. main character energy across the board 👑

---

📜 COPYRIGHT 📜

Copyright © 1998-2003 David Schleef Copyright © 2001-2003, 2005, 2008 Frank Mori Hess Copyright © 2002-2003 Herman Bruyninckx Copyright © 2012 Bernd Porr Copyright © 2012 Ian Abbott Copyright © 2012, 2015 Éric Piel

This document is part of Comedilib. In the context of this document, the term "source code" as defined by the license is interpreted as the XML source.

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, version 2.1 of the License.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.

ngl the "WITHOUT ANY WARRANTY" part is giving real. it's fr fr not covered if something goes sideways. read it, don't skim it 🍓

---

and that's the whole page, bestie 💖 this one dropped from Comedi, dated 03/20/2026, and it's called COMEDI_GET_HARDWARE_(3) — go query some buffer sizes, u got this 🌈🧚