Xref: utzoo comp.sys.ibm.pc:43991 alt.msdos.programmer:1185
Path: utzoo!attcan!uunet!bnrgate!bigsur!bnr-rsc!mlord
From: mlord@bnr-rsc.UUCP (Mark Lord)
Newsgroups: comp.sys.ibm.pc,alt.msdos.programmer
Subject: Fix for TURBO-C 2.0 Text I/O
Keywords: turboc borland c text gotoxy video
Message-ID: <2125@bnr-rsc.UUCP>
Date: 8 Feb 90 15:12:56 GMT
Organization: Bell-Northern Research, Ottawa, Canada
Lines: 37

Hi.  While converting my copy of STEVIE ("vi" knockoff) to use the
built-in Turbo-C text routines (conio.h), I discovered that the library
routines are hardcoded for exactly 25 rows of text.  The number of columns
seems to be correctly obtained from the bios, but the number of rows is
fixed at 25 in the video initialization.

Since I often edit with 30, 40, 50 or 60 lines of text, this was not cool.

I used TLIB and READOBJ together to get a segment listing of the video
initialization module from the libraries, and found an undocumented data
segment called _video .  

Some further probing with TD revealed that this segment holds the internal
copy of the screen/window sizes, as normally queried using getttextinfo().
This makes it trivial to correct this deficiency after startup in any program.

Here is what to do, if YOU want Turbo-C routines to work correctly,
regardless of the number of lines/columns in text mode (mode 3):

	extern struct text_info _video;
	_video.winbottom    = *(char far *) MK_FP(0x40,0x84);
	_video.screenheight = _video.winbottom + 1;

The first line gives you access to the hidden "_video" structure,
the second line reads the actual bottom text row number from the bios
data area, and the third line completes the fixup.

After doing this (like really early in the code eh?), the standard library
gotoxy/insline/deline... routines will then work correctly for screen sizes
other than just the 25-line modes.

That oughta hold us over until May/90..
-- 
 ______Mark S. Lord______________________ ______________________________
|    ..uunet!bnrgate!carrsc!mlord        | These are only MY opinions.  |
| or:  bnr-rsc!mlord@bnrgate             | I charge for official views. |
|________________________________________|______________________________|