---
name: "comedi_get_hardware_buffer_size"
section: "3"
platform: "linux"
package: "libcomedi-dev"
version: "0.11.0+5-1.3+b1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/comedi_get_hardware_buffer_size"
---

# comedi\_get\_hardware\_buffer\_size(3)

get size of subdevice's hardware buffer

## NAME

comedi\_get\_hardware\_buffer\_size - get size of subdevice's hardware buffer

## SYNOPSIS

```
#include <comedilib.h>
```

**int comedi\_get\_hardware\_buffer\_size(comedi\_t** *\*device***, unsigned int** *subdevice***, enum comedi\_io\_direction** *direction***);**

## DESCRIPTION

This function returns the number of bytes the subdevice can hold in it's hardware buffer. The term “hardware buffer” refers to any FIFOs, etc. on the acquisition board itself which are used during streaming commands. This does not include the buffer maintained by the comedi kernel module in host memory, whose size may be queried by **comedi\_get\_buffer\_size**. 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), or **COMEDI\_OUTPUT** to query the output buffer size (e.g., the buffer of an analog output).

## RETURN VALUE

Hardware buffer size in bytes, or -1 on error.

## 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.