COMEDI_MARK_BUFFER_W(3)

NAME
comedi_mark_buffer_written - streaming buffer control

SYNOPSIS

#include <comedilib.h>

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

DESCRIPTION

The function comedi_mark_buffer_written is used on a subdevice that has a Comedi output command in progress. It should only be used if you are using a mmap mapping to write data to Comedi's buffer (as opposed to calling write on the device file descriptor), since Comedi will automatically keep track of how many bytes have been transferred via write calls. This function is used to indicate that the next num_bytes bytes in the buffer are valid and may be sent to the device.

RETURN VALUE

On success, comedi_mark_buffer_written returns the number of bytes successfully marked as written. 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.