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Files Reference
termiox.h File
Purpose
Defines the structure of the termiox file, which
provides the extended terminal interface.
Description
The termiox.h file contains an extended terminal
interface to support asynchronous hardware flow control. It defines the termiox structure and ioctl operations using this structure.
The termiox structure in the termiox.h file contains the following fields:
- x_hflag
- x_cflag
- x_rflag
- x_sflag
The termiox.h file also supports ioctl hardware flow
control operations.
Field |
Descriptions |
x_hflag |
Describes the hardware flow control mode. The possible modes are:
- CDXON
- Enables CD hardware flow control on output. When set, output will
occur only if the `receive line signal detector' (CD) line is raised by the
connected device. If the CD line is dropped by the connected device, output
is suspended until the CD line is raised.
- CTSXON
- Enables CTS hardware flow control on output. When set, output will
occur only if the `clear to send' (CTS) line is raised by the connected device.
If the CTS line is dropped by the connected device, output is suspended until
the CTS line is raised.
- DTRXOFF
- Enables DTR hardware flow control on input. When set, the `data terminal
ready' (DTR) line is raised. If the port needs to have its input stopped,
it will drop the DTR line. It is assumed that the connected device will stop
its output until DTR is raised.
- RTSXOFF
- Enables RTS hardware flow control on input. When set, the `request
to send' (RTS) line is raised. If the port needs to have its input stopped,
it will drop the RTS line. It is assumed that the connected device will stop
its output until RTS is raised.
It is not possible to use simultaneously the following flow control
modes:
Different hardware flow control modes may be selected by setting
the appropriate flags. For example:
- Bi-directional RTS/CTS flow control by setting RTSXOFF and CTSXON
- Bi-directional DTR/CTS flow control by setting DTRXOFF and CTSXON
- Modem control or uni-directional CTS flow control
by setting CTSXON.
|
x_cflag |
Reserved for future use. |
x_rflag |
Reserved for future use. |
x_sflag |
Describes the open discipline. This field must be set before the
first open; it is usually done at configuration time. The possible disciplines
are:
- DTR_OPEN
- DTR open discipline. On open, the discipline raises the `data terminal
ready' (DTR) and `request to send' (RTS) lines, and waits for the `data carrier
detect' (DCD) line to be raised. If the port is opened with the O_NDELAY or O_NONBLOCK flags, the wait is not
done. The DTR and RTS lines are dropped at close time.
- WT_OPEN
- World trade open discipline. On open, the discipline behaves like
the DTR open discipline if not in CDSTL mode. In CDSTL mode, the discipline
does not raise the DTR line until the `ring indicate' (RI) line is raised.
The DTR line is dropped when the DSR line drops for more than 20 milliseconds.
|
Hardware Flow Control Operations
The following ioctl operations are used for hardware flow control. To
use these operations in a program, the program must contain an #include statement for the ioctl.h file. The argument
to these operations is a pointer to a termiox structure.
TCGETX |
Gets the terminal parameters. The current terminal parameters are
stored in the structure. |
TCSETX |
Sets the terminal parameters immediately. The current terminal parameters
are set according to the structure. The change is immediate. |
TCSETXW |
Sets the terminal parameters after end of output. The current terminal
parameters are set according to the structure. The change occurs after all
characters queued for output have been transmitted. This operation should
be used when changing parameters will affect output. |
TCSETXF |
Sets the terminal parameters after end of output and flushes input.
The current terminal parameters are set according to the structure. All characters
queued for output are first transmitted, then all characters queued for input
are discarded, and then the change occurs. |
Related Information
The termios.h file.
The ioctl subroutine.
tty Subsystem Overview in AIX 5L Version 5.2 General Programming Concepts: Writing and Debugging Programs.
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