Parameters |
 |
- controlcode
41 — Enables transparent editing.
- param
16-bit unsigned integer by reference (required)
Passes a value to be used as a subsystem break character in
bits (0:8) and a value to be used as a read terminator in bits (8:8).
Returns the values previously assigned for use as subsystem
break and read terminator characters.
- Notes
An FCONTROL call with a controlcode
value of 41 will place a terminal in transparent editing mode. Also
called unedited mode, this facility allows most special characters
to be read and treated as data. Unlike binary mode, however, which
allows no special character processing to occur, transparent mode
allows a small subset of special characters to retain their meaning.
These characters are listed in Table 8-6 “Special
Characters for Transparent Editing”.
In addition to the characters shown in Table 8-6 “Special
Characters for Transparent Editing”, two other characters have a special meaning
to the system during transparent mode processing. The characters
to be assigned these meanings are specified in the call through
the value entered in param.
Bits (0:8) of param are used to specify
the character that will replace the subsystem break character. Any
character not otherwise defined as a special character in transparent
mode, including the normal subsystem break character ([CTRL]Y),
can be used. If this value is set to 0, subsystem break is disabled.
Bits (8:8) specify the character that will replace the line
termination character (EOR) for the transparent mode read. Any character
not otherwise defined as a special character in transparent mode
may be used.
While binary mode reads terminate only on byte count or a
read timeout, transparent mode reads can be terminated in any of
the following ways:
The read encounters the End-of-Record
(EOR) character defined in param. This character
functions like the [Return] character does in normal
reads. The EOR is echoed but is stripped from the user data. No
carriage return or line feed is sent to the terminal.
The read encounters an Additional End-of-Record
(AEOR) character defined through a previous call to FCONTROL(25).
The read completes with error END OF LINE (FSERR 31), and the AEOR
character is passed with the input data and included in the byte
count. No carriage return or linefeed is sent to the terminal.
The expected byte count specified in the READ, READX,
or FREAD call is reached. The read is terminated normally, and no
carriage return or linefeed is sent to the terminal.
The read limit timer set through a call to FCONTROL(4)
expires. The read terminates with error SOFTWARE TIMEOUT (FSERR
22), and the data entered before the read timed out is returned.
Table 8-6 Special
Characters for Transparent Editing
| Key | Function |
|---|
| AEOR Character | The AEOR character defined through a previous
call to FCONTROL(25). The read terminates in error, and a call to
FCHECK returns an fserrorcode of
31. The AEOR character is passed with the data and included in the
byte count. |
| [Break] | Causes a system break (when enabled) and transfers
control to MPE/iX. If :RESUME is entered transparent
editing is resumed. |
| [CTRL]Q (DC1 or XON) | The "resume output" character
of the XON/XOFF handshake. This character is stripped from the input
data when XON/XOFF protocol is enabled. |
| DC2 | When input as first character, it is stripped
out. A DC1 ([CTRL]Q) is then written to the terminal. When not input
as the first character, DC2 is a data character. |
| [CTRL]S (DC3 or XOFF) | The "halt output" character
of the XON/XOFF handshake. This character is stripped from the input
data when XON/XOFF protocol is enabled. |
Break processing, if not disabled, occurs in transparent mode
the same as in normal editing mode. During the break the terminal
will operate in standard editing mode. The terminal will return
to transparent mode if a :RESUME is entered.
Subsystem break processing also occurs as in normal editing
mode, except that the subsystem break character is defined through
the FCONTROL(41) call.
Because DC1 and DC2 (if the DC2 is the first byte of data)
are recognized as special characters, transparent editing can be
successfully used during block mode reads.
|
| |
|
 | NOTE: When several files are open on a device at the same
time (multiple FOPEN calls were issued), transparent editing will
be in effect for all of the files if it was explicitly enabled for
any one of them. |
|
| |
|
If you enable binary editing, transparent editing is automatically
overridden. When you leave binary mode, however, transparent mode
will still be enabled. Binary mode will only be enabled for the
file on which it is enabled. Other files will continue to operate
in the mode, normal or transparent, that was set before binary was
enabled.
Parity processing is the same in transparent mode as in standard
mode.
Standard editing is restored by calling FCONTROL(41) with
the value of param set to 0. Any FCLOSE call
issued against the terminal will also restore standard editing.
It is possible to enable transparent editing for devices connected
via PAD. However, since the PAD will still expect to see a [Return]
as the data forwarding character, data will not be forwarded from
the terminal immediately after the characters defined as the subsystem
break or EOR characters are typed. The terminal user will need to
press [Return] to cause data to be transmitted,
or wait for the data forwarding timer to expire if it has been set.
The host software will still recognize and act on the characters
defined in param.
If this call is issued against a terminal connected via VT
from an MPE V or HP-UX local client, the subsystem break
character may not be redefined. Bits (0:8) should be the existing
subsystem break character to keep status unchanged or set to 0 to
return to edited mode.
- CCE
Request granted.
- CCG
Not returned by this intrinsic.
- CCL
Failed because the file number specified did not
belong to this process, the device is not a terminal, or an illegal
value was passed in param.
