NAME

       comedi_mark_buffer_read - streaming buffer control

SYNOPSIS

       #include <comedilib.h>

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

DESCRIPTION

       The function comedi_mark_buffer_read is used on a subdevice that has a Comedi input command in progress.
       It should only be used if you are using a mmap mapping to read data from Comedi's buffer (as opposed to
       calling read on the device file descriptor), since Comedi will automatically keep track of how many bytes
       have been transferred via read calls. This function is used to indicate that the next num_bytes bytes in
       the buffer are no longer needed and may be discarded.

RETURN VALUE

       On success, comedi_mark_buffer_read returns the number of bytes successfully marked as read. The return
       value may be less than the num_bytes. On failure, -1 is returned.

AUTHORS

       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.

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.

Comedi                                             03/31/2024                            COMEDI_MARK_BUFFER_R(3)