link itlibdos
August 14, 1996; Richard L. Goerwitz
Requires: MS-DOS, coexpressions
See also: iscreen.icn, iolib.icn, itlib.icn
This file is in the public domain.
The following library represents a series of rough functional
equivalents to the standard UNIX low-level termcap routines. They
are not meant as exact termlib clones. Nor are they enhanced to
take care of magic cookie terminals, terminals that use \D in their
termcap entries, or, in short, anything I felt would not affect my
normal, day-to-day work with ANSI and vt100 terminals. At this
point I'd recommend trying iolib.icn instead of itlibdos.icn. Iolib
is largely DOS-UNIX interchangeable, and it does pretty much every-
thing itlibdos.icn does.
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Notes on the MS-DOS version:
There are two basic reasons for using the I/O routines
contained in this package. First, by using a set of generalized
routines, your code will become much more readable. Secondly, by
using a high level interface, you can avoid the cardinal
programming error of hard coding things like screen length and
escape codes into your programs.
To use this collection of programs, you must do two things.
First, you must add the line "device=ansi.sys" (or the name of some
other driver, like zansi.sys, nansi.sys, or nnansi.sys [=new
nansi.sys]) to your config.sys file. Secondly, you must add two
lines to your autoexec.bat file: 1) "set TERM=ansi-mono" and 2)
"set TERMCAP=\location\termcap." The purpose of setting the TERM
variable is to tell this program what driver you are using. If you
have a color system, use "ansi-color" instead of "ansi-mono," and
if you are using nansi or zansi instead of vanilla ansi, use one of
these names instead of the "ansi" (e.g. "zansi-mono"). The purpose
of setting TERMCAP is to make it possible to determine where the
termcap file is located. The termcap file (which should have been
packed with this library as termcap.dos) is a short database of all
the escape sequences used by the various terminal drivers. Set
TERMCAP so that it reflects the location of this file (which should
be renamed as termcap, for the sake of consistency with the UNIX
version). Naturally, you must change "\location\" above to reflect
the correct path on your system. With some distributions, a second
termcap file may be included (termcap2.dos). Certain games work a
lot better using this alternate file. To try it out, rename it to
termcap, and set TERMCAP to its location.
Although I make no pretense here of providing here a complete
introduction to the format of the termcap database file, it will be
useful, I think, to explain a few basic facts about how to use this
program in conjunction with it. If, say, you want to clear the
screen, add the line,
iputs(getval("cl"))
to your program. The function iputs() outputs screen control
sequences. Getval retrieves a specific sequence from the termcap
file. The string "cl" is the symbol used in the termcap file to
mark the code used to clear the screen. By executing the
expression "iputs(getval("cl"))," you are 1) looking up the "cl"
(clear) code in the termcap database entry for your terminal, and
the 2) outputting that sequence to the screen.
Some other useful termcap symbols are "ce" (clear to end of
line), "ho" (go to the top left square on the screen), "so" (begin
standout mode), and "se" (end standout mode). To output a
boldfaced string, str, to the screen, you would write -
iputs(getval("so"))
writes(str)
iputs(getval("se"))
You could write "writes(getval("so") || str || getval("se")), but
this would only work for DOS. Some UNIX terminals require padding,
and iputs() handles them specially. Normally you should not worry
about UNIX quirks under DOS. It is in general wise, though, to
separate out screen control sequences, and output them via iputs().
It is also heartily to be recommended that MS-DOS programmers
try not to assume that everyone will be using a 25-line screen.
Some terminals are 24-line. Some 43. Some have variable window
sizes. If you want to put a status line on, say, the 2nd-to-last
line of the screen, then determine what that line is by executing
"getval("li")." The termcap database holds not only string-valued
sequences, but numeric ones as well. The value of "li" tells you
how many lines the terminal has (compare "co," which will tell you
how many columns). To go to the beginning of the second-to-last
line on the screen, type in:
iputs(igoto(getval("cm"), 1, getval("li")-1))
The "cm" capability is a special capability, and needs to be output
via igoto(cm,x,y), where cm is the sequence telling your computer
to move the cursor to a specified spot, x is the column, and y is
the row. The expression "getval("li")-1" will return the number of
the second-to-last line on your screen.