Re: Low Level Ada

[Jeffrey Carter <spam@spam.com>]

Stephane Richard wrote:

> For instance, let's say I want to create an Array that would hold characters
> with the goal to send it to the video card directly (address $B800).
> 
> Could I take an array of Characters, and "move it" to address $B800 ?  or
> something like it?

Assuming you're talking about an OS such as DOS, where I've done this 
kind of thing in Turbo Pascal and Ada 83, sure. The basic premise is 
something like

type Screen_Image is array (...) of ...; -- char/attr pairs, or whatever

Screen_Memory : Screen_Image;
for Screen_Memory'address use ...;

Work_Space : Screen_Image;

...

-- Mess around with Work_Space

Screen_Memory := Work_Space;

This was fast enough, on a 16 MHz 386, that you didn't see any flicker, 
and I was working in graphics mode, with a lot more bytes than character 
mode.

In Turbo Pascal I had to use pointers, and set one pointer to point to 
the screen memory. Then I did something like

Screen^ := Work^;

(equivalent to Screen.all := Work.all;)

HTH.

-- 
Jeff Carter
"I wave my private parts at your aunties."
Monty Python & the Holy Grail
13