NAME
io_width_ctl — set width of data path (OBSOLETED AT 10.30)
SYNOPSIS
#include <dvio.h>
int io_width_ctl(int eid, int width);
DESCRIPTION
io_width_ctl()
enables you to select the width of the data path to be used
for a particular interface.
eid
is an entity identifier of an open
HP-IB,
Centronics-compatible parallel interface, or
GPIO
device file obtained from an
open(),
dup(),
fcntl(),
or
creat()
call.
width
is an integer specifying the width of the data path in bits.
An error is given if an invalid width is specified.
Specifying a width with this function sets the width for all
users of the device file associated with the given entity id.
When first opened, the default width is 8 bits.
For the
GPIO
interface only widths of 8 and 16 bits are currently supported.
For the
HP-IB
and Centronics-compatible parallel interfaces,
only a width of 8 bits is supported.
RETURN VALUE
io_width_ctl()
returns 0 if successful, and -1 if an error was encountered.
ERRORS
io_width_ctl()
fails under the following circumstances and sets
errno
(see
errno(2))
to the value indicated:
- [EBADF]
eid
does not refer to an open file.
- [ENOTTY]
eid
does not refer to a channel device file.
- [EINVAL]
the specified
width
is not supported on this device file.
AUTHOR
io_width_ctl()
was developed by HP.
