Summary

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	File:     iolib.icn
	
	Subject:  Procedures for termlib support
	
	Author:   Richard L. Goerwitz (with help from Norman Azadian)

	Date:     August 14, 1996

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   This file is in the public domain.

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	Version:  1.13

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  The following library represents a series of rough functional
  equivalents to the standard UNIX low-level termcap routines.  It is
  not meant as an exact termlib clone.  Nor is it enhanced to take
  care of magic cookie terminals, terminals that use \D in their
  termcap entries, or archaic terminals that require padding.  This
  library is geared mainly for use with ANSI and VT-100 devices.
  Note that this file may, in most instances, be used in place of the
  older UNIX-only itlib.icn file.  It essentially replaces the DOS-
  only itlibdos routines.  For DOS users not familiar with the whole
  notion of generalized screen I/O, I've included extra documentation
  below.  Please read it.

  The sole disadvantage of this over the old itlib routines is that
  iolib.icn cannot deal with archaic or arcane UNIX terminals and/or
  odd system file arrangements.  Note that because these routines
  ignore padding, they can (unlike itlib.icn) be run on the NeXT and
  other systems which fail to implement the -g option of the stty
  command.  Iolib.icn is also simpler and faster than itlib.icn.

  I want to thank Norman Azadian for suggesting the whole idea of
  combining itlib.icn and itlibdos.icn into one distribution, for
  suggesting things like letting drive specifications appear in DOS
  TERMCAP environment variables, and for finding several bugs (e.g.
  the lack of support for %2 and %3 in cm).  Although he is loathe
  to accept this credit, I think he deserves it.

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  Contents:

  setname(term)
	Use only if you wish to initialize itermlib for a terminal
  other than what your current environment specifies.  "Term" is the
  name of the termcap entry to use.  Normally this initialization is
  done automatically, and need not concern the user.

  getval(id)
	Works something like tgetnum, tgetflag, and tgetstr.  In the
  spirit of Icon, all three have been collapsed into one routine.
  Integer valued caps are returned as integers, strings as strings,
  and flags as records (if a flag is set, then type(flag) will return
  "true").  Absence of a given capability is signalled by procedure
  failure.

  igoto(cm,destcol,destline) - NB:  default 1 offset (*not* zero)!
	Analogous to tgoto.  "Cm" is the cursor movement command for
  the current terminal, as obtained via getval("cm").  Igoto()
  returns a string which, when output via iputs, will cause the
  cursor to move to column "destcol" and line "destline."  Column and
  line are always calculated using a *one* offset.  This is far more
  Iconish than the normal zero offset used by tgoto.  If you want to
  go to the first square on your screen, then include in your program
  "iputs(igoto(getval("cm"),1,1))."

  iputs(cp,affcnt)
	Equivalent to tputs.  "Cp" is a string obtained via getval(),
  or, in the case of "cm," via igoto(getval("cm"),x,y).  Affcnt is a
  count of affected lines.  It is completely irrelevant for most
  modern terminals, and is supplied here merely for the sake of
  backward compatibility with itlib, a UNIX-only version of these
  routines (one which handles padding on archaic terminals).

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  Notes for MS-DOS users:

	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, you could use "ansi-color" instead of
  "ansi-mono," although for compatibility with a broader range of
  users, it would perhaps be better to stick with mono.  The purpose
  of setting TERMCAP is to make it possible to determine where the
  termcap database 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
  across UNIX and MS-DOS spectra).  If desired, you can also try
  using termcap2.dos.  Certain games work a lot better using this
  alternate file.  To try it out, rename it to termcap, and set
  the environment variable TERMCAP to its location.

	Although the authors make no pretense of providing here a
  complete introduction to the format of the termcap database file,
  it will be useful, we believe, 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 can also write "writes(getval("so") || str || getval("se")),
  but this would make reimplementation for UNIX terminals that
  require padding rather difficult.

	It is also heartily to be recommended that MS-DOS programmers
  try not to assume that everyone will be using a 25-line screen.
  Most 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.

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  Requires: UNIX or MS-DOS, co-expressions

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  See also: itlib.icn, iscreen.icn

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This file is part of the (main) package.

Decode(s)

check_features()

er(func, msg, errnum)

getentry(name, termcap_string)

getname()

getval(id)

igoto(cm, col, line)

iputs(cp, affcnt)

maketc_table(entry)

read_file(f)

setname(name)