.\" authorization. *
.\"***************************************************************************
.\"
-.\" $Id: term.5,v 1.33 2020/02/02 23:34:34 tom Exp $
+.\" $Id: term.5,v 1.38 2020/07/25 21:56:02 tom Exp $
.TH term 5
.ie \n(.g .ds `` \(lq
.el .ds `` ``
The compiled file is created with the \fB@TIC@\fP program,
and read by the routine \fBsetupterm\fP(3X).
The file is divided into six parts:
-the header,
-terminal names,
-boolean flags,
-numbers,
-strings,
-and
-string table.
+.RS 5
+.TP 3
+a) \fIheader\fP,
+.TP 3
+b) \fIterminal names\fP,
+.TP 3
+c) \fIboolean flags\fP,
+.TP 3
+d) \fInumbers\fP,
+.TP 3
+e) \fIstrings\fP, and
+.TP 3
+f) \fIstring table\fP.
+.RE
.PP
-The header section begins the file.
+The \fIheader\fP section begins the file.
This section contains six short integers in the format
described below.
These integers are
.RS 5
.TP 5
-(1) the magic number (octal 0432);
+(1) the \fImagic number\fP (octal 0432);
.TP 5
-(2) the size, in bytes, of the names section;
+(2) the size, in bytes, of the \fIterminal names\fP section;
.TP 5
-(3) the number of bytes in the boolean section;
+(3) the number of bytes in the \fIboolean flags\fP section;
.TP 5
-(4) the number of short integers in the numbers section;
+(4) the number of short integers in the \fInumbers\fP section;
.TP 5
-(5) the number of offsets (short integers) in the strings section;
+(5) the number of offsets (short integers) in the \fIstrings\fP section;
.TP 5
-(6) the size, in bytes, of the string table.
+(6) the size, in bytes, of the \fIstring table\fP.
.RE
.PP
-Short integers are stored in two 8-bit bytes.
+The capabilities in the
+\fIboolean flags\fP,
+\fInumbers\fP, and
+\fIstrings\fP
+sections are in the same order as the file <term.h>.
+.PP
+Short integers are signed, in the range \-32768 to 32767.
+They are stored as two 8-bit bytes.
The first byte contains the least significant 8 bits of the value,
and the second byte contains the most significant 8 bits.
(Thus, the value represented is 256*second+first.)
-The value \-1 is represented by the two bytes 0377, 0377; other negative
-values are illegal.
-This value generally
-means that the corresponding capability is missing from this terminal.
-Note that this format corresponds to the hardware of the \s-1VAX\s+1
+This format corresponds to the hardware of the \s-1VAX\s+1
and \s-1PDP\s+1-11 (that is, little-endian machines).
Machines where this does not correspond to the hardware must read the
integers as two bytes and compute the little-endian value.
.PP
-The terminal names section comes next.
+Numbers in a terminal description,
+whether they are entries in the \fInumbers\fP or \fIstrings\fP table,
+are positive integers.
+Boolean flags are treated as positive one-byte integers.
+In each case, those positive integers represent a terminal capability.
+The terminal compiler @TIC@ uses negative integers to handle the cases where
+a capability is not available:
+.bP
+If a capability is absent from this terminal,
+@TIC@ stores a \-1 in the corresponding table.
+.IP
+The integer value \-1 is represented by two bytes 0377, 0377.
+.br
+Absent boolean values are represented by the byte 0 (false).
+.bP
+If a capability has been canceled from this terminal,
+@TIC@ stores a \-2 in the corresponding table.
+.IP
+The integer value \-2 is represented by two bytes 0377, 0376.
+.br
+The boolean value \-2 is represented by the byte 0376.
+.br
+.bP
+Other negative values are illegal.
+.PP
+The \fIterminal names\fP section comes after the \fIheader\fP.
It contains the first line of the terminfo description,
listing the various names for the terminal,
separated by the \*(``|\*('' character.
-The section is terminated with an \s-1ASCII NUL\s+1 character.
+The \fIterminal names\fP section is terminated
+with an \s-1ASCII NUL\s+1 character.
.PP
-The boolean flags have one byte for each flag.
-This byte is either 0 or 1 as the flag is present or absent.
-The capabilities are in the same order as the file <term.h>.
+The \fIboolean flags\fP section has one byte for each flag.
+Boolean capabilities are either 1 or 0 (true or false)
+according to whether the terminal supports the given capability or not.
.PP
-Between the boolean section and the number section,
+Between the \fIboolean flags\fP section and the \fInumber\fP section,
a null byte will be inserted, if necessary,
-to ensure that the number section begins on an even byte (this is a
-relic of the PDP\-11's word-addressed architecture, originally
-designed in to avoid IOT traps induced by addressing a word on an
-odd byte boundary).
+to ensure that the \fInumber\fP section begins on an even byte
+This is a relic of the PDP\-11's word-addressed architecture,
+originally designed to avoid traps induced
+by addressing a word on an odd byte boundary.
All short integers are aligned on a short word boundary.
.PP
-The numbers section is similar to the flags section.
+The \fInumbers\fP section is similar to the \fIboolean flags\fP section.
Each capability takes up two bytes,
and is stored as a little-endian short integer.
-If the value represented is \-1, the capability is taken to be missing.
.PP
-The strings section is also similar.
-Each capability is stored as a short integer, in the format above.
-A value of \-1 means the capability is missing.
-Otherwise, the value is taken as an offset from the beginning
-of the string table.
+The \fIstrings\fP section is also similar.
+Each capability is stored as a short integer.
+The capability value is an index into the \fIstring table\fP.
+.PP
+The \fIstring table\fP is the last section.
+It contains all of the values of string capabilities referenced in
+the \fIstrings\fP section.
+Each string is null-terminated.
Special characters in ^X or \ec notation are stored in their
interpreted form, not the printing representation.
Padding information $<nn> and parameter information %x are
stored intact in uninterpreted form.
-.PP
-The final section is the string table.
-It contains all the values of string capabilities referenced in
-the string section.
-Each string is null terminated.
.SS EXTENDED STORAGE FORMAT
The previous section describes the conventional terminfo binary format.
With some minor variations of the offsets (see PORTABILITY),
total compiled entries cannot exceed 32768 bytes in the extended format.
.bP
the name field cannot exceed 128 bytes.
+.PP
+Compiled entries are limited to 32768 bytes because offsets into the
+\fIstrings table\fP use two-byte integers.
+The legacy format could have supported 32768-byte entries,
+but was limited a virtual memory page's 4096 bytes.
.SH FILES
\*d/*/* compiled terminal capability data base
.SH SEE ALSO
projects / ncurses.git / blobdiff