scsh-0.6/doc/scsh-manual/tty.tex

%&latex -*- latex -*-
% Fix OXTABS footnote bug
% Figures should be dumped out earlier? Pack two to a page?

\section{Terminal device control}
\label{sect:tty}

\newcommand{\fr}[1]{\makebox[0pt][r]{#1}}

Scsh provides a complete set of routines for manipulating terminal
devices---putting them in ``raw'' mode, changing and querying their
special characters, modifying their I/O speeds, and so forth.
The scsh interface is designed both for generality and portability
across different Unix platforms, so you don't have to rewrite your
program each time you move to a new system.
We've also made an effort to use reasonable, Scheme-like names for
the multitudinous named constants involved, so when you are reading
code, you'll have less likelihood of getting lost in a bewildering
maze of obfuscatory constants named \ex{ICRNL}, \ex{INPCK}, \ex{IUCLC},
and \ex{ONOCR}.

This section can only lay out the basic functionality of the terminal
device interface.
For further details, see the termios(3) man page on your system,
or consult one of the standard {\Unix} texts.

\subsection{Portability across OS variants}
Terminal-control software is inescapably complex, ugly, and low-level.
Unix variants each provide their own way of controlling terminal
devices, making it difficult to provide interfaces that are
portable across different Unix systems.
Scsh's terminal support is based primarily upon the {\Posix} termios
interface.
Programs that can be written using only the {\Posix} interface are likely
to be widely portable.

The bulk of the documentation that follows consists of several pages worth
of tables defining different named constants that enable and disable different
features of the terminal driver.
Some of these flags are {\Posix}; others are taken from the two common
branches of Unix development, SVR4 and 4.3+ Berkeley.
Scsh guarantees that the non-{\Posix} constants will be bound identifiers.
\begin{itemize}
\item If your OS supports a particular non-{\Posix} flag, 
      its named constant will be bound to the flag's value.
\item If your OS doesn't support the flag, its named constant
      will be present, but bound to \sharpf.
\end{itemize}
This means that if you want to use SVR4 or Berkeley features in a program,
your program can portably test the values of the flags before using 
them---the flags can reliably be referenced without producing OS-dependent
``unbound variable'' errors.

Finally, note that although {\Posix}, SVR4, and Berkeley cover the lion's
share of the terminal-driver functionality, 
each operating system inevitably has non-standard extensions.
While a particular scsh implementation may provide these extensions,
they are not portable, and so are not documented here.

\subsection{Miscellaneous procedures}
\defun{tty?}{fd/port}{\boolean}
\begin{desc}
Return true if the argument is a tty.
\end{desc}

\defun{tty-file-name}{fd/port}{\str}
\begin{desc}
The argument \var{fd/port} must be a file descriptor or port open on a tty.
Return the file-name of the tty.
\end{desc}

\subsection{The tty-info record type}

The primary data-structure that describes a terminal's mode is
a \ex{tty-info} record, defined as follows:
\index{tty-info record type}
\indextt{tty-info:control-chars}
\indextt{tty-info:input-flags}
\indextt{tty-info:output-flags}
\indextt{tty-info:control-flags}
\indextt{tty-info:local-flags}
\indextt{tty-info:input-speed}
\indextt{tty-info:output-speed}
\indextt{tty-info:min}
\indextt{tty-info:time}
\indextt{tty-info?}
\begin{code}
(define-record tty-info
  control-chars  ; String: Magic input chars
  input-flags    ; Int: Input processing
  output-flags   ; Int: Output processing
  control-flags  ; Int: Serial-line control
  local-flags    ; Int: Line-editting UI
  input-speed    ; Int: Code for input speed
  output-speed   ; Int: Code for output speed
  min            ; Int: Raw-mode input policy
  time)          ; Int: Raw-mode input policy\end{code}

\subsubsection{The control-characters string}
The \ex{control-chars} field is a character string;
its characters may be indexed by integer values taken from 
table~\ref{table:ttychars}.

As discussed above, 
only the {\Posix} entries in table~\ref{table:ttychars} are guaranteed
to be legal, integer indices.
A program can reliably test the OS to see if the non-{\Posix} 
characters are supported by checking the index constants.
If the control-character function is supported by the terminal driver, 
then the corresponding index will be bound to an integer;
if it is not supported, the index will be bound to \sharpf.

To disable a given control-character function, set its corresponding
entry in the \ex{tty-info:control-chars} string to the
special character \exi{disable-tty-char} 
(and then use the \ex{(set-tty-info \var{fd/port} \var{info})} procedure
to update the terminal's state).

\subsubsection{The flag fields}
The \ex{tty-info} record's \ex{input-flags}, \ex{output-flags},
\ex{control-flags}, and \ex{local-flags} fields are all bit sets
represented as two's-complement integers.
Their values are composed by or'ing together values taken from
the named constants listed in tables~\ref{table:ttyin} 
through \ref{table:ttylocal}.

As discussed above, 
only the {\Posix} entries listed in these tables are guaranteed
to be legal, integer flag values.
A program can reliably test the OS to see if the non-{\Posix} 
flags are supported by checking the named constants.
If the feature is supported by the terminal driver, 
then the corresponding flag will be bound to an integer;
if it is not supported, the flag will be bound to \sharpf.

%%%%% I managed to squeeze this into the DEFINE-RECORD's comments.
% Here is a small table classifying the four flag fields by
% the kind of features they determine:
% \begin{center}
% \begin{tabular}{|ll|}\hline
% Field                 & Affects \\ \hline \hline
% \ex{input-flags}      & Processing of input chars \\
% \ex{output-flags}     & Processing of output chars \\
% \ex{control-flags}    & Controlling of terminal's serial line \\
% \ex{local-flags}      & Details of the line-editting user interface \\
% \hline
% \end{tabular}
% \end{center}

%%%
%%% The figures used to go here.
%%%

\subsubsection{The speed fields}
The \ex{input-speed} and \ex{output-speed} fields determine the
I/O rate of the terminal's line.
The value of these fields is an integer giving the speed
in bits-per-second.
The following speeds are supported by {\Posix}:
\begin{center}
\begin{tabular}{rrrr}
0        & 134 & 600  & 4800  \\
50       & 150 & 1200 & 9600  \\
75       & 200 & 1800 & 19200 \\
110      & 300 & 2400 & 38400 \\
\end{tabular}
\end{center}
Your OS may accept others; it may also allow the special symbols
\ex{'exta} and \ex{'extb}.

\subsubsection{The min and time fields}
The integer \ex{min} and \ex{time} fields determine input blocking
behaviour during non-canonical (raw) input; otherwise, they are ignored.
See the termios(3) man page for further details.

Be warned that {\Posix} allows the base system call's representation
of the \ex{tty-info} record to share storage for the \ex{min} field
and the \ex{ttychar/eof} element of the control-characters string,
and for the \ex{time} field and the \ex{ttychar/eol} element
of the control-characters string.
Many implementations in fact do this.

To stay out of trouble, set the \ex{min} and \ex{time} fields only
if you are putting the terminal into raw mode;
set the eof and eol control-characters only if you are putting
the terminal into canonical mode.
It's ugly, but it's {\Unix}.

\subsection{Using tty-info records}

\defun{make-tty-info}{if of cf lf ispeed ospeed min time}
                   {tty-info-record}
\defunx{copy-tty-info}{tty-info-record}{tty-info-record}
\begin{desc}
These procedures make it possible to create new \ex{tty-info} records.
The typical method for creating a new record is to copy one retrieved
by a call to the \ex{tty-info} procedure, then modify the copy as desired.
Note that the \ex{make-tty-info} procedure does not take a parameter
to define the new record's control characters.\footnote{
        Why? Because the length of the string varies from Unix to Unix.
        For example, the word-erase control character (typically control-w)
        is provided by most Unixes, but not part of the {\Posix} spec.}
Instead, it simply returns a \ex{tty-info} record whose control-character
string has all elements initialised to {\Ascii} nul.
You may then install the special characters by assigning to the string.
Similarly, the control-character string in the record produced by
\ex{copy-tty-info} does not share structure with the string in the record
being copied, so you may mutate it freely.
\end{desc}


\defun{tty-info}{[fd/port/fname]}{tty-info-record}
\begin{desc}
The \var{fd/port/fname} parameter is an integer file descriptor or 
Scheme I/O port opened on a terminal device, 
or a file-name for a terminal device; it defaults to the current input port.
This procedure returns a \ex{tty-info} record describing the terminal's
current mode.
\end{desc}

\defun {set-tty-info/now}  {fd/port/fname info}{no-value}
\defunx{set-tty-info/drain}{fd/port/fname info}{no-value}
\defunx{set-tty-info/flush}{fd/port/fname info}{no-value}
\begin{desc}
The \var{fd/port/fname} parameter is an integer file descriptor or 
Scheme I/O port opened on a terminal device, 
or a file-name for a terminal device.
The procedure chosen determines when and how the terminal's mode is altered:
\begin{center}
\begin{tabular}{|ll|} \hline
Procedure & Meaning \\ \hline \hline
\ex{set-tty-info/now}   & Make change immediately. \\
\ex{set-tty-info/drain} & Drain output, then change. \\
\ex{set-tty-info/flush} & Drain output, flush input, then change. \\ \hline
\end{tabular}
\end{center}
\oops{If I had defined these with the parameters in the reverse order,
      I could have made \var{fd/port/fname} optional. Too late now.}
\end{desc}

\subsection{Other terminal-device procedures}
\defun{send-tty-break}{[fd/port/fname duration]}{no-value}
\begin{desc}
The \var{fd/port/fname} parameter is an integer file descriptor or 
Scheme I/O port opened on a terminal device, 
or a file-name for a terminal device; it defaults to the current output port.
Send a break signal to the designated terminal.
A break signal is a sequence of continuous zeros on the terminal's transmission
line.

The \var{duration} argument determines the length of the break signal.
A zero value (the default) causes a break of between 
0.25 and 0.5 seconds to be sent;
other values determine a period in a manner that will depend upon local
community standards.
\end{desc}

\defun{drain-tty}{[fd/port/fname]}{no-value}
\begin{desc}
The \var{fd/port/fname} parameter is an integer file descriptor or 
Scheme I/O port opened on a terminal device, 
or a file-name for a terminal device; it defaults to the current output port.

This procedure waits until all the output written to the
terminal device has been transmitted to the device.
If \var{fd/port/fname} is an output port with buffered I/O
enabled, then the port's buffered characters are flushed before
waiting for the device to drain.
\end{desc}

\defun {flush-tty/input} {[fd/port/fname]}{no-value}
\defunx{flush-tty/output}{[fd/port/fname]}{no-value}
\defunx{flush-tty/both}  {[fd/port/fname]}{no-value}
\begin{desc}
The \var{fd/port/fname} parameter is an integer file descriptor or 
Scheme I/O port opened on a terminal device, 
or a file-name for a terminal device; it defaults to the current input
port (\ex{flush-tty/input} and \ex{flush-tty/both}),
or output port (\ex{flush-tty/output}).

These procedures discard the unread input chars or unwritten
output chars in the tty's kernel buffers. 
\end{desc}

\defun {start-tty-output}{[fd/port/fname]} {no-value}
\defunx{stop-tty-output} {[fd/port/fname]} {no-value}
\defunx{start-tty-input} {[fd/port/fname]} {no-value}
\defunx{stop-tty-input}  {[fd/port/fname]} {no-value}
\begin{desc}
These procedures can be used to control a terminal's input and output flow.
The \var{fd/port/fname} parameter is an integer file descriptor or 
Scheme I/O port opened on a terminal device, 
or a file-name for a terminal device; it defaults to the current input
or output port.

The \ex{stop-tty-output} and \ex{start-tty-output} procedures suspend
and resume output from a terminal device.
The \ex{stop-tty-input} and \ex{start-tty-input} procedures transmit
the special STOP and START characters to the terminal with the intention
of stopping and starting terminal input flow.
\end{desc}

% --- Obsolete ---
% \defun {encode-baud-rate}{speed}{code}
% \defunx{decode-baud-rate}{code}{speed}
% \begin{desc}
% These procedures can be used to map between the special codes
% that are legal values for the \ex{tty-info:input-speed} and
% \ex{tty-info:output-speed} fields, and actual integer bits-per-second speeds.
% The codes are the values bound to the
% \ex{baud/4800}, \ex{baud/9600}, and other named constants defined above.
% For example:
% \begin{code}
% (decode-baud-rate baud/9600) {\evalto} 9600
% 
% ;;; These two expressions are identical:
% (set-tty-info:input-speed ti baud/14400)
% (set-tty-info:input-speed ti (encode-baud-rate 14400))\end{code}
% \end{desc}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\subsection{Control terminals, sessions, and terminal process groups}

\defun{open-control-tty}{tty-name [flags]}{port}
\begin{desc}
This procedure opens terminal device \var{tty-name} as the process'
control terminal 
(see the \ex{termios} man page for more information on control terminals).
The \var{tty-name} argument is a file-name such as \ex{/dev/ttya}.
The \var{flags} argument is a value suitable as the second argument
to the \ex{open-file} call; it defaults to \ex{open/read+write}, causing
the terminal to be opened for both input and output.

The port returned is an input port if the \var{flags} permit it, 
otherwise an output port. 
\RnRS/\scm/scsh do not have input/output ports,
so it's one or the other. 
However, you can get both read and write ports open on a terminal
by opening it read/write, taking the result input port,
and duping it to an output port with \ex{dup->outport}.

This procedure guarantees to make the opened terminal the
process' control terminal only if the process does not have
an assigned control terminal at the time of the call.
If the scsh process already has a control terminal, the results are undefined.

To arrange for the process to have no control terminal prior to calling
this procedure, use the \ex{become-session-leader} procedure.

%\oops{The control terminal code was added just before release time
%      for scsh release 0.4. Control terminals are one of the less-standardised
%      elements of Unix. We can't guarantee that the terminal is definitely
%      attached as a control terminal; we were only able to test this out
%      on HP-UX. If you intend to use this feature on your OS, you should
%      test it out first. If your OS requires the use of the \ex{TIOCSCTTY}
%      \ex{ioctl}, uncomment the appropriate few lines of code in the
%      file \ex{tty1.c} and send us email.}
\end{desc}

\defun{become-session-leader}{}{\integer}
\begin{desc}
This is the C \ex{setsid()} call.
{\Posix} job-control has a three-level hierarchy:
session/process-group/process. 
Every session has an associated control terminal.
This procedure places the current process into a brand new session,
and disassociates the process from any previous control terminal.
You may subsequently use \ex{open-control-tty} to open a new control
terminal.

It is an error to call this procedure if the current process is already
a process-group leader.
One way to guarantee this is not the case is only to call this procedure
after forking.
\end{desc}


\defun {tty-process-group}{fd/port/fname}{\integer}
\defunx{set-tty-process-group}{fd/port/fname pgrp}{\undefined}
\begin{desc}
This pair of procedures gets and sets the process group of a given
terminal.
\end{desc}

\defun{control-tty-file-name}{}{\str}
\begin{desc}
Return the file-name of the process' control tty.
On every version of Unix of which we are aware, this is just the string
\ex{"/dev/tty"}.
However, this procedure uses the official Posix interface, so it is more
portable than simply using a constant string.
\end{desc}


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\subsection{Pseudo-terminals}
Scsh implements an interface to Berkeley-style pseudo-terminals.

\defun{fork-pty-session}{thunk}{[process pty-in pty-out tty-name]}
\begin{desc}
This procedure gives a convenient high-level interface to pseudo-terminals.
It first allocates a pty/tty pair of devices, and then forks a child
to execute procedure \var{thunk}.
In the child process
\begin{itemize}
\item Stdio and the current I/O ports are bound to the terminal device.
\item The child is placed in its own, new session
            (see \ex{become\=session\=leader}).
\item The terminal device becomes the new session's controlling terminal
            (see \ex{open-control-tty}).
\item The \ex{(error-output-port)} is unbuffered.
\end{itemize}

The \ex{fork-pty-session} procedure returns four values:
the child's process object, two ports open on the controlling pty device,
and the name of the child's corresponding terminal device.
\end{desc}

\defun{open-pty}{}{pty-inport tty-name}
\begin{desc}
This procedure finds a free pty/tty pair, and opens the pty device
with read/write access.
It returns a port on the pty, 
and the name of the corresponding terminal device.

The port returned is an input port---Scheme doesn't allow input/output
ports.
However, you can easily use \ex{(dup->outport \var{pty-inport})}
to produce a matching output port.
You may wish to turn off I/O buffering for this output port.
\end{desc}


\defun {pty-name->tty-name}{pty-name}{tty-name}
\defunx{tty-name->pty-name}{tty-name}{pty-name}
\begin{desc}
These two procedures map between corresponding terminal and pty controller
names.
For example,
\begin{code}
(pty-name->tty-name "/dev/ptyq3") {\evalto} "/dev/ttyq3"
(tty-name->pty-name "/dev/ttyrc") {\evalto} "/dev/ptyrc"\end{code}

\remark{This is rather Berkeley-specific. SVR4 ptys are rare enough that
        I've no real idea if it generalises across the Unix gap. Experts
        are invited to advise. Users feel free to not worry---the predominance
        of current popular Unix systems use Berkeley ptys.}
\end{desc}

\defunx{make-pty-generator}{}{\proc}
\begin{desc}
This procedure returns a generator of candidate pty names.
Each time the returned procedure is called, it produces a
new candidate.
Software that wishes to search through the set of available ptys
can use a pty generator to iterate over them.
After producing all the possible ptys, a generator returns {\sharpf}
every time it is called.
Example:
\begin{code}
(define pg (make-pty-generator))
(pg) {\evalto} "/dev/ptyp0"
(pg) {\evalto} "/dev/ptyp1"
        \vdots
(pg) {\evalto} "/dev/ptyqe"
(pg) {\evalto} "/dev/ptyqf"    \textit{(Last one)}
(pg) {\evalto} {\sharpf}
(pg) {\evalto} {\sharpf}
        \vdots\end{code}
\end{desc}


% Flag tables
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% Control-chars indices
%%%%%%%%%%%%%%%%%%%%%%%
\begin{table}[p]
\begin{center}
\begin{tabular}{|lll|} \hline
Scsh & C & Typical char \\
\hline\hline
{\Posix} & & \\
\exi{ttychar/delete-char}       & \ex{ERASE}    & del \\
\exi{ttychar/delete-line}       & \ex{KILL}     & \verb|^U| \\
\exi{ttychar/eof}               & \ex{EOF}      & \verb|^D| \\
\exi{ttychar/eol}               & \ex{EOL}      & \\
\exi{ttychar/interrupt}         & \ex{INTR}     & \verb|^C| \\
\exi{ttychar/quit}              & \ex{QUIT}     & \verb|^\| \\
\exi{ttychar/suspend}           & \ex{SUSP}     & \verb|^Z| \\
\exi{ttychar/start}             & \ex{START}    & \verb|^Q| \\
\exi{ttychar/stop}              & \ex{STOP}     & \verb|^S| \\

\hline\hline
{SVR4 and 4.3+BSD} & & \\
\exi{ttychar/delayed-suspend}   & \ex{DSUSP}    & \verb|^Y| \\
\exi{ttychar/delete-word}       & \ex{WERASE}   & \verb|^W| \\
\exi{ttychar/discard}           & \ex{DISCARD}  & \verb|^O| \\
\exi{ttychar/eol2}              & \ex{EOL2}     & \\
\exi{ttychar/literal-next}      & \ex{LNEXT}    & \verb|^V| \\
\exi{ttychar/reprint}           & \ex{REPRINT}  & \verb|^R| \\

\hline\hline
{4.3+BSD} & & \\
\exi{ttychar/status}            & \ex{STATUS}   & \verb|^T| \\
\hline
\end{tabular}
\end{center}
\caption{Indices into the \protect\ex{tty-info} record's 
         \protect\var{control-chars} string,
         and the character traditionally found at each index.
         Only the indices for the {\Posix} entries are guaranteed to
         be non-\sharpf.}
\label{table:ttychars}
\end{table}

% Input flags
%%%%%%%%%%%%%
\begin{table}[p]
\begin{center}\small
\begin{tabular}{|lll|} \hline
Scsh & C & Meaning \\ 
\hline\hline
\Posix & & \\
\exi{ttyin/check-parity}
                        & \ex{INPCK}    & Check parity. \\
\exi{ttyin/ignore-bad-parity-chars}
                        & \ex{IGNPAR}   & Ignore chars with parity errors. \\
\exi{ttyin/mark-parity-errors}
                        & \ex{PARMRK}   & Insert chars to mark parity errors.\\
\exi{ttyin/ignore-break}
                        & \ex{IGNBRK}   & Ignore breaks. \\
\exi{ttyin/interrupt-on-break}
                        & \ex{BRKINT}   & Signal on breaks. \\
\exi{ttyin/7bits}
                        & \ex{ISTRIP}   & Strip char to seven bits. \\
\exi{ttyin/cr->nl}
                        & \ex{ICRNL}    & Map carriage-return to newline. \\
\exi{ttyin/ignore-cr}
                        & \ex{IGNCR}    & Ignore carriage-returns. \\
\exi{ttyin/nl->cr}
                        & \ex{INLCR}    & Map newline to carriage-return. \\
\exi{ttyin/input-flow-ctl}
                        & \ex{IXOFF}    & Enable input flow control. \\
\exi{ttyin/output-flow-ctl}
                        & \ex{IXON}     & Enable output flow control. \\

\hline\hline
{SVR4 and 4.3+BSD} & & \\
\exi{ttyin/xon-any}             & \ex{IXANY} & Any char restarts after stop. \\
\exi{ttyin/beep-on-overflow}    & \ex{IMAXBEL} & Ring bell when queue full. \\

\hline\hline
{SVR4} & & \\
\exi{ttyin/lowercase}           & \ex{IUCLC} & Map upper case to lower case. \\
\hline
\end{tabular}
\end{center}
\caption{Input-flags. These are the named flags for the \protect\ex{tty-info} 
         record's \protect\var{input-flags} field.
         These flags generally control the processing of input chars.
         Only the {\Posix} entries are guaranteed to be non-\sharpf.
         }
\label{table:ttyin}
\end{table}

% Output flags
%%%%%%%%%%%%%%
\begin{table}[p]
\begin{center}%\small
\begin{tabular}{|lll|} \hline
Scsh & C & Meaning \\ \hline\hline

\multicolumn{3}{|l|}{\Posix} \\
\exi{ttyout/enable}  & \ex{OPOST} & Enable output processing. \\

\hline\hline
\multicolumn{3}{|l|}{SVR4 and 4.3+BSD} \\
\exi{ttyout/nl->crnl}   & \ex{ONLCR} & Map nl to cr-nl. \\

\hline\hline
\multicolumn{3}{|l|}{4.3+BSD} \\
\exi{ttyout/discard-eot}    & \ex{ONOEOT}       & Discard EOT chars. \\
\exi{ttyout/expand-tabs}    & \ex{OXTABS}\footnote{
                        Note this is distinct from the SVR4-equivalent
                        \ex{ttyout/tab-delayx} flag defined in 
                        table~\ref{table:ttydelays}.}
                      & Expand tabs. \\

\hline\hline
\multicolumn{3}{|l|}{SVR4} \\
\exi{ttyout/cr->nl}             & \ex{OCRNL} & Map cr to nl. \\
\exi{ttyout/nl-does-cr}         & \ex{ONLRET}& Nl performs cr as well. \\
\exi{ttyout/no-col0-cr}         & \ex{ONOCR} & No cr output in column 0. \\
\exi{ttyout/delay-w/fill-char}  & \ex{OFILL} & Send fill char to delay. \\
\exi{ttyout/fill-w/del}         & \ex{OFDEL} & Fill char is {\Ascii} DEL. \\
\exi{ttyout/uppercase}          & \ex{OLCUC} & Map lower to upper case. \\
\hline
\end{tabular}
\end{center}
\caption{Output-flags. These are the named flags for the \protect\ex{tty-info}
         record's \protect\var{output-flags} field.
         These flags generally control the processing of output chars.
         Only the {\Posix} entries are guaranteed to be non-\sharpf.}
\label{table:ttyout}
\end{table}

% Delay flags
%%%%%%%%%%%%%
\begin{table}[p]
\begin{tabular}{r|ll|} \cline{2-3}
& Value & Comment \\ \cline{2-3}
{Backspace delay}       & \exi{ttyout/bs-delay}         & Bit-field mask \\
                        & \exi{ttyout/bs-delay0}        & \\
                        & \exi{ttyout/bs-delay1}        & \\

\cline{2-3}
{Carriage-return delay} & \exi{ttyout/cr-delay}         & Bit-field mask \\
                        & \exi{ttyout/cr-delay0}        & \\
                        & \exi{ttyout/cr-delay1}        & \\
                        & \exi{ttyout/cr-delay2}        & \\
                        & \exi{ttyout/cr-delay3}        & \\

\cline{2-3}
{Form-feed delay}       & \exi{ttyout/ff-delay}         & Bit-field mask \\
                        & \exi{ttyout/ff-delay0}        & \\
                        & \exi{ttyout/ff-delay1}        & \\

\cline{2-3}
{Horizontal-tab delay}  & \exi{ttyout/tab-delay}        & Bit-field mask \\
                        & \exi{ttyout/tab-delay0}       & \\
                        & \exi{ttyout/tab-delay1}       & \\
                        & \exi{ttyout/tab-delay2}       & \\
                        & \exi{ttyout/tab-delayx}       & Expand tabs \\

\cline{2-3}
{Newline delay}         & \exi{ttyout/nl-delay}         & Bit-field mask \\
                        & \exi{ttyout/nl-delay0}        & \\
                        & \exi{ttyout/nl-delay1}        & \\ 

\cline{2-3}
{Vertical tab delay}    & \exi{ttyout/vtab-delay}       & Bit-field mask \\
                        & \exi{ttyout/vtab-delay0}      & \\
                        & \exi{ttyout/vtab-delay1}      & \\

\cline{2-3}
{All}                   & \exi{ttyout/all-delay}  & Total bit-field mask \\
\cline{2-3}
\end{tabular}

\caption{Delay constants. These are the named flags for the
         \protect\ex{tty-info} record's \protect\var{output-flags} field.
         These flags control the output delays associated with printing
         special characters.
         They are non-{\Posix}, and have non-{\sharpf} values
         only on SVR4 systems.}
\label{table:ttydelays}
\end{table}

% Control flags
%%%%%%%%%%%%%%%
\begin{table}[p]
\begin{center}%\small
\begin{tabular}{|lll|} \hline
Scsh & C & Meaning \\

\hline\hline
\multicolumn{3}{|l|}{\Posix} \\
\exi{ttyc/char-size}    & \ex{CSIZE}    & Character size mask \\
\exi{ttyc/char-size5}   & \ex{CS5}      & 5 bits \\
\exi{ttyc/char-size6}   & \ex{CS6}      & 6 bits \\
\exi{ttyc/char-size7}   & \ex{CS7}      & 7 bits \\
\exi{ttyc/char-size8}   & \ex{CS8}      & 8 bits \\
\exi{ttyc/enable-parity}& \ex{PARENB}   & Generate and detect parity. \\
\exi{ttyc/odd-parity}   & \ex{PARODD}   & Odd parity. \\
\exi{ttyc/enable-read}  & \ex{CREAD}    & Enable reception of chars. \\
\exi{ttyc/hup-on-close} & \ex{HUPCL}    & Hang up on last close. \\
\exi{ttyc/no-modem-sync}& \ex{LOCAL}    & Ignore modem lines. \\
\exi{ttyc/2-stop-bits}  & \ex{CSTOPB}   & Send two stop bits. \\

\hline\hline
\multicolumn{3}{|l|}{4.3+BSD} \\
\exi{ttyc/ignore-flags}         & \ex{CIGNORE}  & Ignore control flags. \\
\exi{ttyc/CTS-output-flow-ctl}  & \verb|CCTS_OFLOW| & CTS flow control of output \\
\exi{ttyc/RTS-input-flow-ctl}   & \verb|CRTS_IFLOW| & RTS flow control of input \\
\exi{ttyc/carrier-flow-ctl}     & \ex{MDMBUF} & \\
\hline
\end{tabular}
\end{center}

\caption{Control-flags. These are the named flags for the \protect\ex{tty-info}
         record's \protect\var{control-flags} field.
         These flags generally control the details of the terminal's
         serial line.
         Only the {\Posix} entries are guaranteed to be non-\sharpf.}
\label{table:ttyctl}
\end{table}

% Local flags
%%%%%%%%%%%%%
\begin{table}[p]
\begin{center}\small
\begin{tabular}{|lll|} \hline
Scsh & C & Meaning \\

\hline\hline
\multicolumn{3}{|l|}{\Posix} \\
\exi{ttyl/canonical}    & \ex{ICANON}    & Canonical input processing. \\
\exi{ttyl/echo}         & \ex{ECHO}      & Enable echoing. \\
\exi{ttyl/echo-delete-line} & \ex{ECHOK}   & Echo newline after line kill. \\
\exi{ttyl/echo-nl}      & \ex{ECHONL}    & Echo newline even if echo is off. \\
\exi{ttyl/visual-delete}& \ex{ECHOE}     & Visually erase chars. \\
\exi{ttyl/enable-signals} & \ex{ISIG}    & Enable \verb|^|C, \verb|^|Z signalling. \\
\exi{ttyl/extended}     & \ex{IEXTEN}    & Enable extensions. \\
\exi{ttyl/no-flush-on-interrupt}
                        & \ex{NOFLSH}    &  Don't flush after interrupt. \\
\exi{ttyl/ttou-signal}  & \ex{ITOSTOP}   & \ex{SIGTTOU} on background output. \\

\hline\hline
\multicolumn{3}{|l|}{SVR4 and 4.3+BSD} \\
\exi{ttyl/echo-ctl}             & \ex{ECHOCTL}  
                                & Echo control chars as ``\verb|^X|''. \\
\exi{ttyl/flush-output}         & \ex{FLUSHO}   & Output is being flushed. \\
\exi{ttyl/hardcopy-delete}      & \ex{ECHOPRT}  & Visual erase for hardcopy. \\
\exi{ttyl/reprint-unread-chars} & \ex{PENDIN}   & Retype pending input. \\
\exi{ttyl/visual-delete-line}   & \ex{ECHOKE}   & Visually erase a line-kill. \\

\hline\hline
\multicolumn{3}{|l|}{4.3+BSD} \\
\exi{ttyl/alt-delete-word}      & \ex{ALTWERASE}  & Alternate word erase algorithm \\
\exi{ttyl/no-kernel-status}     & \ex{NOKERNINFO} & No kernel status on \verb|^T|. \\

\hline\hline
\multicolumn{3}{|l|}{SVR4} \\
\exi{ttyl/case-map}     & \ex{XCASE} & Canonical case presentation \\
\hline
\end{tabular}
\end{center}

\caption{Local-flags. These are the named flags for the \protect\ex{tty-info}
         record's \protect\var{local-flags} field.
         These flags generally control the details of the line-editting
         user interface.
         Only the {\Posix} entries are guaranteed to be non-\sharpf.}
\label{table:ttylocal}
\end{table}
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