'\" t
.\"     Title: comedi_mark_buffer_written
.\"    Author: David Schleef <ds@schleef.org>
.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
.\"      Date: 12/30/2018
.\"    Manual: Comedi reference
.\"    Source: Comedi
.\"  Language: English
.\"
.TH "COMEDI_MARK_BUFFER_W" "3" "12/30/2018" "Comedi" "Comedi reference"
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.SH "NAME"
comedi_mark_buffer_written \- streaming buffer control
.SH "SYNOPSIS"
.sp
.ft B
.nf
#include <comedilib\&.h>
.fi
.ft
.HP \w'int\ comedi_mark_buffer_written('u
.BI "int comedi_mark_buffer_written(comedi_t\ *\ " "device" ", unsigned\ int\ " "subdevice" ", unsigned\ int\ " "num_bytes" ");"
.SH "DESCRIPTION"
.PP
The function
\fBcomedi_mark_buffer_written\fR
is used on a subdevice that has a Comedi output command in progress\&. It should only be used if you are using a
\fBmmap\fR
mapping to write data to Comedi\*(Aqs buffer (as opposed to calling
\fBwrite\fR
on the device file descriptor), since Comedi will automatically keep track of how many bytes have been transferred via
\fBwrite\fR
calls\&. This function is used to indicate that the next
\fInum_bytes\fR
bytes in the buffer are valid and may be sent to the device\&.
.SH "RETURN VALUE"
.PP
On success,
\fBcomedi_mark_buffer_written\fR
returns the number of bytes successfully marked as written\&. The return value may be less than the
\fInum_bytes\fR\&. On failure,
\-1
is returned\&.
.PP
.SH "AUTHORS"
.PP
\fBDavid Schleef\fR <\&ds@schleef.org\&>
.RS 4
Author.
.RE
.PP
\fBFrank Mori Hess\fR <\&fmhess@users.sourceforge.net\&>
.RS 4
Author.
.RE
.PP
\fBHerman Bruyninckx\fR <\&Herman.Bruyninckx@mech.kuleuven.ac.be\&>
.RS 4
Author.
.RE
.PP
\fBBernd Porr\fR <\&tech@linux-usb-daq.co.uk\&>
.RS 4
Author.
.RE
.PP
\fBIan Abbott\fR <\&abbotti@mev.co.uk\&>
.RS 4
Author.
.RE
.PP
\fB\('Eric Piel\fR <\&piel@delmic.com\&>
.RS 4
Author.
.RE
.SH "COPYRIGHT"
.br
Copyright \(co 1998-2003 David Schleef
.br
Copyright \(co 2001-2003, 2005, 2008 Frank Mori Hess
.br
Copyright \(co 2002-2003 Herman Bruyninckx
.br
Copyright \(co 2012 Bernd Porr
.br
Copyright \(co 2012 Ian Abbott
.br
Copyright \(co 2012, 2015 \('Eric Piel
.br
.PP
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.
.PP
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.
.PP
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.
.PP
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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