eucioctl(5) DG/UX 5.4.2 eucioctl(5)
NAME
eucioctl - generic interface to EUC handling TTY drivers and modules
SYNOPSIS
#include <sys/eucioctl.h>
ioctl(int fd, ISTR, struct strioctl *sb);
DESCRIPTION
This interface is implemented in TTY drivers and pushable STREAMS
modules that handle EUC codes. It is intended as a generic interface
for EUC handling, to eliminate an explosion of ``module specific''
ioctl calls that would otherwise be necessary, and to provide
uniformity in dealing with EUC codesets in the TTY subsystem.
Several calls are defined. The first two calls take an argument,
which is expected to be a pointer to an eucioc structure, defined in
the header file <sys/eucioctl.h>:
struct eucioc {
unsigned char eucw[4];
unsigned char scrw[4];
};
typedef struct eucioc eucioct;
In all cases, these calls return non-zero on failure. Failure should
be usually taken as an indication that the current driver, or line
discipline module, does not support EUC in which case errno will be
set to EINVAL. For the EUCWSET and EUCWGET calls errno will be set
will be set to EPROTO if the struct eucioc argument is invalid.
EUCWSET This call takes a pointer to an eucioc structure,
and uses it to set the EUC line discipline's local
definition for the codeset widths to be used for
subsequent operations. Within the STREAM, the line
discipline may optionally notify other modules of
this setting via MCTL messages.
EUCWGET This call takes a pointer to an eucioc structure,
and returns in it the EUC codeset widths currently
in use by the EUC line discipline. It need be
recognized only by line discipline modules.
The following calls take no arguments. They should only fail if the
driver (at the bottom of the TTY STREAM) does not recognize EUC
codes. Drivers that support EUC, whether the STREAM contains modules
that respond to the calls or not, will recognize the calls and
acknowledge them. These calls are normally only interpreted by
modules that have modes other than ASCII, and/or do some form of I/O
conversion that normally prevents a program from receiving non-EUC
characters in its byte stream. All of these calls, when received by
modules, are passed down the TTY STREAM, to be ultimately
acknowledged by the TTY driver.
Licensed material--property of copyright holder(s) 1
eucioctl(5) DG/UX 5.4.2 eucioctl(5)
EUCMSAVE This call has no effect on modules that are
currently in ASCII mode. Otherwise (i.e., for
modules not in ASCII mode), the following actions
are taken by all modules that recognize this call:
(1) the current ``mode'' status is saved, (2) the
mode is changed to ASCII mode immediately.
EUCMREST If a mode was saved via a previous EUCMSAVE call,
the saved mode is restored, and the ``saved state''
flag is cleared. If the mode was not previously
saved, this call has no effect. (The exact
semantics are somewhat dependent on the module,
since some modules may respond to specific user-
requests to switch modes, even while a mode is
being saved via EUCMSAVE.)
EUCIXLOFF If a module is currently in a state where ``input
conversion'' is being performed on the incoming
byte stream, then input conversion is turned off,
and the module's ``mode'' status is saved. If no
input conversion is being performed, there is no
effect on the module. The purpose of this call is
to provide a way of insuring a ``pure'' byte stream
to the program. The byte stream while input
conversion is off is, of course, not guaranteed to
be a stream of EUC characters. Turning off input
conversion is roughly equivalent to the old concept
of ``raw'' mode, if used in conjunction with ICANON
off. It should normally not be used by
applications.
EUCIXLON If a module previously saved its state and turned
off input conversion, then input conversion is
restored (i.e., turned back on); otherwise, there
is no effect.
EUCOXLOFF In a manner similar to EUCIXLOFF, any ``output
conversion'' is turned off, and the current mode
status saved.
EUCOXLON In a manner similar to EUCIXLON, any saved
``output conversion'' status is restored (i.e.,
output conversion is turned back on if previously
turned off via EUCOXLOFF).
Limitations
Drivers and modules that support EUC should all respond appropriately
to these calls, depending on their type. Line disciplines must
respond to EUCWSET and EUCWGET, changing their current codeset
sizes to match EUCWSET requests. All TTY STREAMS modules that do
any input or output conversion should recognize the other calls;
modules that do no codeset conversion are not required to recognize
the calls, but must pass them through. Drivers that support EUC TTY
STREAMS must all acknowledge the ON/OFF calls, whether the drivers
Licensed material--property of copyright holder(s) 2
eucioctl(5) DG/UX 5.4.2 eucioctl(5)
themselves are affected or not, since these calls are purposely not
acknowledged by modules which receive them; they are intended to be
made available for affecting all modules in the whole STREAM.
FILES
/usr/include/sys/eucioctl.h
SEE ALSO
eucset(1).
NOTES
Adherence to this protocol for all EUC handling modules is strongly
encouraged in order to increase portability and language-independence
of applications. These calls are intended as a small set of
primitives to help reduce an anticipated plethora of module- and
language-dependent operations.
Licensed material--property of copyright holder(s) 3