[comp.sys.atari.st] How do i get the lineoffset in bytes ?

hintz@quando.UUCP (Stefan Hintz) (03/02/90)

In article <9002221043.AA00452@freya.math.dmswwu> ONM07@DMSWWU1A.BITNET (Julian Reschke) writes:
>Please stop using Line-A-functions NOW. All programs using Line-A won't
>and CAN't run properly on Mega-St-Color-cards (8-Bit == 256 Colors!!!) or
>on the TT.

I fully agree to that.

 But how do i get the number of bytes in a picture-line , without calling
linea_init(). ($A000) .
 Yes for the three 'normal' ST-ScreenResolutions you
can divide the pixels per line (work_out[0]+1) thrue the number of planes,
(you can get this value with vq_extnd(); taking workout[4] , i guess)
and divide that thrue eight.
 But if you try this method with 'Overscan' (also called 'Hyperscreen', 50% more
Screen-Resolution for 3DM, in ST-Magazin) or with a 256 Greyscale-card, you will
fail. Because there is some memory in each scanline which is not used for
display.

My question:
Is there any legal possibility to ask via VDI or AES about the offset in bytes
between two picture-lines? Is there another way than LineA, to find the
VDI-ESCape variables? Will the TT-VDI have new VDI-Funktions to solve this
problem? How do i findout how much memory is needed for the physical Screen.

Stefan Hintz, Dortmund, West Germany