NAME
io_speed_ctl() — inform system of required transfer speed (OBSOLETED AT 10.30)
SYNOPSIS
#include <dvio.h>
int io_speed_ctl(int eid, int speed);
DESCRIPTION
io_speed_ctl()
selects the data transfer speed for a data path
used for a particular interface.
The transfer method (i.e.,
DMA
or fast-handshake) chosen by the system
is determined by the speed requirements.
eid
is an entity identifier of an open
HP-IB
raw bus, Centronics-compatible parallel, or
GPIO
device file obtained from an
open(),
dup(),
fcntl(),
or
creat()
call.
speed
is an integer specifying the data transfer speed
in Kbytes per second (one Kbyte equals 1024 bytes).
RETURN VALUE
io_speed_ctl()
returns 0 if successful, and -1 otherwise.
ERRORS
io_speed_ctl()
fails under the following condition, and sets
errno
to the value indicated:
- [ENOTTY]
eid
does not refer to channel device file.
- [EBADF]
eid
does not refer to an open file.
DEPENDENCIES
DMA
is the only supported transfer method.
AUTHOR
io_speed_ctl()
was developed by HP.
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