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Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxt!houxm!ihnp4!pegasus!hansen
From: hansen@pegasus.UUCP (Tony L. Hansen)
Newsgroups: net.info-terms
Subject: Re: need termcap/cm help - tvi955
Message-ID: <2575@pegasus.UUCP>
Date: Tue, 10-Sep-85 21:01:19 EDT
Article-I.D.: pegasus.2575
Posted: Tue Sep 10 21:01:19 1985
Date-Received: Wed, 11-Sep-85 08:06:42 EDT
References: <362@varian.UUCP>
Reply-To: hansen@pegasus.UUCP (60545451-Tony L. Hansen;LZ 3B-315;6243)
Distribution: net
Organization: AT&T Information Systems, Lincroft NJ
Lines: 57
Keywords: termcap terminfo
Summary: termcap can't do it

< We just received some TeleVideo 955 terminals -- this a new model -- cheap
< ...
< The problem:
< 	cursor motion (cm)!
< 	For columns 1 through 80, the cursor motion is the same as for other
< 	TeleVideo terminals (and many other terminals as well) -- 
< 		cm = \E=%+\040%+\040
< ...
< 	BUT .. for columns 81 through 132, the sequence is:
< 		ESC = r ~ c
< 		and the value of c is calculated by subtracting 80 from
< 		the column number and then adding space.

Such a sequence cannot be done with termcap as it currently exists. Your best
bet is, if you can't switch to terminfo, to run the terminal exclusively in
80 column mode and forget 132 column mode.

It is exactly for reasons such as this that the stack architecture used by
terminfo was introduced. With termcap, everytime a new addressing scheme
came out which didn't match a previous scheme, new code had to be written
for libtermlib.a and the world relinked with the new library. With terminfo,
the format is encoded entirely within the string and instantiated at runtime.

Hence, to program the above sequence in terminfo:

    cup=\E=%p1%' '%+%c%p2%?%{80}%>%t%p2~%{48}%-%c%e%p2%' '%+%c%;,

If you're not familiar with what this means, a breakdown follows.

					Tony Hansen
					ihnp4!pegasus!hansen

    cup=\E=%p1%' '%+%c%p2%?%{80}%>%t%p2~%{48}%-%c%e%p2%' '%+%c%;,
	^  ^  ^   ^ ^ ^  ^ ^    ^ ^ ^  ^^    ^ ^ ^ ^  ^   ^ ^ ^
	1  2  3   4 5 6  7 8    9 a b  cd    e f g h  i   j k l

    1) output ESC =
    2) push the first parameter, the row, onto the stack
    3) push a space onto the stack
    4) add the row and space
    5) output the sum as a character
    6) push the second parameter, the column, onto the stack
    7) if
    8)     push 80 onto the stack
    9)     compare: row > 80?
    a) then
    b)     push the column back onto the stack
    c)     output '~'
    d)     push 48 onto the stack (80 - 040)
    e)     subtract (col - 80 + 040)
    f)     output the difference as a character
    g) else
    h)     push the column back onto the stack
    i)     push a space onto the stack
    j)     add the column and the space
    k)     output the sum as a character
    l) fi