Article View: comp.sys.atari.st
Article #41659Re: How do you create non-scrolling screen regions?
From: Jwahar R. Bammi
Date: Thu, 08 Mar 1990 06:27
Date: Thu, 08 Mar 1990 06:27
37 lines
1948 bytes
1948 bytes
In article <2344@ultb.isc.rit.edu> ajy2208@ultb.isc.rit.edu (A.J. Yarusso) writes:
> Hopefully I won't have to write custom screen i/o routines to do
No you wont have to! there is an advertised lineA variable (V_CEL_MY)
just to do this: the short (16 bit) at offset -0x2a (-42 decimal) bytes from
the lineA base can be set to a number N to get effectively a N+1 line
scrolling region vt52. For instance if you want the N'th line to
be a status line, and have a (N-1)x80 vt52, you would set
char *linea_base = (base of lineA from linea0 (0xA000));
short *V_CEL_MY = (short *)(linea_base - 42L);
short save;
save = *V_CEL_MY;
*V_CEL_MY = save - 1;
....
and before terminating:
*V_CEL_MY = save;
its probably not a good idea to assume that the screen is 25 lines
high (or even 80 wide (with can be determined from V_CEL_MX at offset -44)).
To write to the bottom line(s):
- you can use something like v_gtext()
- or you can change *V_CEL_Y, write to the line using
Bcon/Ccon traps, and change *V_CEL_Y back, and so on..
Some of this stuff is documented in <line.h> that i posted here a while
back, or in the more current version of that file that comes with the
Gnu C library (available via FTP from dsrgsun.ces.crwu.edu).
--
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!mailrus!usenet.ins.cwru.edu!usenet.INS.CWRU.Edu!bammi From: bammi@curie.ces.cwru.edu (Jwahar R. Bammi) Newsgroups: comp.sys.atari.st Subject: Re: How do you create non-scrolling screen regions? Message-ID: <BAMMI.90Mar8012815@curie.ces.cwru.edu> Date: 8 Mar 90 06:27:05 GMT References: <2344@ultb.isc.rit.edu> Sender: news@usenet.ins.cwru.edu Organization: Case Western Reserve University Lines: 37 In-reply-to: ajy2208@ultb.isc.rit.edu's message of 6 Mar 90 22:07:13 GMT