COMEDI_MARK_BUFFER_R(3)

💖 COMEDI_MARK_BUFFER_R — bestie's guide to the Comedi reference 💖

okay so real talk, this is page COMEDI_MARK_BUFFER_R(3) from the Comedi reference, and it's literally just one little function that deserves way more hype than it gets. let's get into it 🫶

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✨ NAME ✨

comedi_mark_buffer_read — streaming buffer control 💅

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🎀 SYNOPSIS 🎀

#include <comedilib.h>

int comedi_mark_buffer_read(comedi_t * device, unsigned int subdevice,
                            unsigned int num_bytes);

like, that's it. that's the whole entrance. she's small but she's mighty ✨

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🌸 DESCRIPTION 🌸

so comedi_mark_buffer_read is the girl you call when your subdevice has a Comedi input command in progress. she's niche and she knows it 😌

⚠️ important: she should only be used if you're reading data from Comedi's buffer through an mmap mapping — NOT by calling read on the device file descriptor. why?? because when you use read, Comedi just automatically keeps track of how many bytes have been transferred all by herself. no notes. she's got it handled. 💅

so when you're doing the mmap thing and Comedi can't do that bookkeeping for you, that's when you call this function: it tells Comedi that the next num_bytes bytes sitting in the buffer are no longer needed and may be discarded. bye bestie, we don't need you anymore, go girl 🦋

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👑 RETURN VALUE 👑

• on success → comedi_mark_buffer_read returns the number of bytes successfully marked as read 🔥
• heads up though: the return value may be less than the num_bytes you asked for. not a bug, just how she is 🙈
• on failure → -1 is returned 💀

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💜 AUTHORS 💜

the icons who made this happen, one by one, no skipping:

• 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 authors, one function, main character energy all around 👑

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🌈 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.

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💌 ok that's the whole page, you're officially fluent in comedi_mark_buffer_read. go mark some bytes as read, bestie, you got this fr fr 🫶

this was page COMEDI_MARK_BUFFER_R(3) from the Comedi set, version 03/20/2026 — and that's the whole vibe check, no cap 💖✨🎀🦋🌸💅