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GETCHLIB.ICN
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1993-01-27
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############################################################################
#
# File: getchlib.icn
#
# Subject: Procedures for getch for UNIX
#
# Author: Richard L. Goerwitz
#
# Date: January 17, 1992
#
###########################################################################
#
# Version: 1.14
#
###########################################################################
#
# Implementing getch() is a much, much more complex affair under UNIX
# than it is under, say, MS-DOS. This library represents one,
# solution to the problem - one which can be run as a library, and
# need not be compiled into the run-time system. Note that it will
# not work on all systems. In particular, certain Suns (with a
# screwy stty command) and the NeXT 1.0 OS (lacking the -g option for
# stty) do not run getchlib properly. See the bugs section below for
# workarounds.
#
# Four basic utilities are included here:
#
# getch() - waits until a keystroke is available &
# returns it without displaying it on the screen
# getche() - same as getch() only with echo
# getse(s) - like getche() only for strings. The optional
# argument s gives getse() something to start with. Use this
# if, say, you want to read single characters in cbreak mode,
# but get more input if the character read is the first part
# of a longer command. If the user backspaces over everything
# that has been input, getse() fails. Returns on \r or \n.
# reset_tty() - absolutely vital routine for putting the cur-
# rent tty line back into cooked mode; call it before exiting
# or you will find yourself with a locked-up terminal; use it
# also if you must temporarily restore the terminal to cooked
# mode
#
# Note that getse() *must* be used in place of read(&input) if you
# are planning on using getch() or getche(), since read(&input)
# assumes a tty with "sane" settings.
#
# Warning: The routines below do not do any sophisticated output
# processing. As noted above, they also put your tty line in raw
# mode. I know, I know: "Raw is overkill - use cbreak." But in
# a world that includes SysV, one must pick a lowest common denomi-
# nator. And no, icanon != cbreak.
#
# BUGS: These routines will not work on systems that do not imple-
# ment the -g option for the stty command. The NeXT workstation is
# an example of such a system. Tisk, tisk. If you are on a BSD
# system where the network configuration makes stty | more impossible,
# then substitute /usr/5bin/stty (or whatever your system calls the
# System V stty command) for /bin/stty in this file. If you have no
# SysV stty command online, then you can try replacing every instance
# of "stty -g 2>&1" below with "stty -g 2>&1 1> /dev/tty" or
# something similar.
#
############################################################################
#
# Example program:
#
# The following program is a simple file viewer. To run, it
# needs to be linked with itlib.icn, iscreen.icn, and this file
# (getchlib.icn).
#
# procedure main(a)
#
# # Simple pager/file searcher for UNIX systems. Must be linked
# # with itlib.icn and iscreen.icn.
#
# local intext, c, s
#
# # Open input file
# intext := open(a[1],"r") | {
# write(&errout,"Can't open input file.")
# exit(1)
# }
#
# # Initialize screen
# clear()
# print_screen(intext) | exit(0)
#
# # Prompt & read input
# repeat {
# iputs(igoto(getval("cm"), 1, getval("li")))
# emphasize()
# writes("More? (y/n or /search):")
# write_ce(" ")
# case c := getche() of {
# "y" : print_screen(intext) | break
# " " : print_screen(intext) | break
# "n" : break
# "q" : break
# "/" : {
# iputs(igoto(getval("cm"), 1, getval("li")))
# emphasize()
# writes("Enter search string:")
# write_ce(" ")
# pattern := GetMoreInput()
# /pattern | "" == pattern & next
# # For more complex patterns, use findre() (IPL findre.icn)
# if not find(pattern, s := !intext) then {
# iputs(igoto(getval("cm"), 1, getval("li")))
# emphasize()
# write_ce("String not found.")
# break
# }
# else print_screen(intext, s) | break
# }
# }
# }
#
# reset_tty()
# write()
# exit(0)
#
# end
#
# procedure GetMoreInput(c)
#
# local input_string
# static BS
# initial BS := getval("bc") | "\b"
#
# /c := ""
# if any('\n\r', chr := getch())
# then return c
# else {
# chr == BS & fail
# writes(chr)
# input_string := getse(c || chr) | fail
# if any('\n\r', input_string)
# then fail else (return input_string)
# }
#
# end
#
# procedure print_screen(f,s)
#
# if /s then
# begin := 1
# # Print top line, if one is supplied
# else {
# iputs(igoto(getval("cm"), 1, 1))
# write_ce(s ? tab(getval("co") | 0))
# begin := 2
# }
#
# # Fill the screen with lines from f; clear and fail on EOF.
# every i := begin to getval("li") - 1 do {
# iputs(igoto(getval("cm"), 1, i))
# if not write_ce(read(f) ? tab(getval("co") | 0)) then {
# # Clear remaining lines on the screen.
# every j := i to getval("li") do {
# iputs(igoto(getval("cm"), 1, j))
# iputs(getval("ce"))
# }
# iputs(igoto(getval("cm"), 1, i))
# fail
# }
# }
# return
#
# end
#
# procedure write_ce(s)
#
# normal()
# iputs(getval("ce")) |
# writes(repl(" ",getval("co") - *s))
# writes(s)
# return
#
# end
#
############################################################################
#
# Requires: UNIX
#
# Links: itlib.icn
#
############################################################################
global c_cc, current_mode # what mode are we in, raw or cooked?
record termio_struct(vintr,vquit,verase,vkill)
procedure getse(s)
# getse() - like getche, only for strings instead of single chars
#
# This procedure *must* be used instead of read(&input) if getch
# and/or getche are to be used, since these put the current tty
# line in raw mode.
#
# Note that the buffer can be initialized by calling getse with a
# string argument. Note also that, as getse now stands, it will
# fail if the user backspaces over everything that has been input.
# This change does not coincide with its behavior in previous ver-
# sions. It can be changed by commenting out the line "if *s < 1
# then fail" below, and uncommenting the line "if *s < 1 then
# next."
local chr
static BS
initial {
BS := getval("bc") | "\b"
if not getval("bs") then {
reset_tty()
stop("Your terminal can't backspace!")
}
}
/s := ""
repeat {
case chr := getch() | fail of {
"\r"|"\n" : return s
c_cc.vkill : {
if *s < 1 then next
every 1 to *s do writes(BS)
s := ""
}
c_cc.verase : {
# if *s < 1 then next
writes(BS) & s := s[1:-1]
if *s < 1 then fail
}
default: writes(chr) & s ||:= chr
}
}
end
procedure setup_tty()
change_tty_mode("setup")
return
end
procedure reset_tty()
# Reset (global) mode switch to &null to show we're in cooked mode.
current_mode := &null
change_tty_mode("reset")
return
end
procedure getch()
local chr
# If the global variable current_mode is null, then we have to
# reset the terminal to raw mode.
if /current_mode := 1 then
setup_tty()
chr := reads(&input)
case chr of {
c_cc.vintr : reset_tty() & stop() # shouldn't hard code this in
c_cc.vquit : reset_tty() & stop()
default : return chr
}
end
procedure getche()
local chr
# If the global variable current_mode is null, then we have to
# reset the terminal to raw mode.
if /current_mode := 1 then
setup_tty()
chr := reads(&input)
case chr of {
c_cc.vintr : reset_tty() & stop()
c_cc.vquit : reset_tty() & stop()
default : writes(chr) & return chr
}
end
procedure change_tty_mode(switch)
# global c_cc (global record containing values for kill, etc. chars)
local get_term_params, i
static reset_string
initial {
getval("li") # check to be sure itlib is set up
find("unix",map(&features)) |
stop("change_tty_mode: These routines must run under UNIX.")
get_term_params := open("/bin/stty -g 2>&1","pr")
reset_string := !get_term_params
close(get_term_params)
reset_string ? {
# tab upto the fifth field of the output of the stty -g cmd
# fields of stty -g seem to be the same as those of the
# termio struct, except that the c_line field is missing
every 1 to 4 do tab(find(":")+1)
c_cc := termio_struct("\x03","\x1C","\x08","\x15")
every i := 1 to 3 do {
c_cc[i] := char(integer("16r"||tab(find(":"))))
move(1)
}
c_cc[i+1] := char(integer("16r"||tab(0)))
}
}
if switch == "setup"
then system("/bin/stty -echo raw")
else system("/bin/stty "||reset_string)
return
end