Message-ID: <35DFD709.886F2F11@geocities.com>
From: Merlin <merlin__ AT geocities DOT com>
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Newsgroups: comp.os.msdos.djgpp
Subject: Re: VESA: hints, clue but no examples
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Date: Sun, 23 Aug 1998 08:51:05 GMT
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To: djgpp AT delorie DOT com
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Endlisnis wrote:

> Merlin wrote:
>
> > >     This is especially important in protected mode because switching banks requires changing to
> > > real-mode.
> > ouch...using __dpmi_int int the middle of drawing something that needed to be fast would be a killer...
>
>     There is an quicker way to switch banks, in the ModeInfoBlock for a given VESA mode, there is a far
> pointer to a function which will switch banks for you.  That only requires
> __djgpp_simulate_real_mode_procedure_retf  <spelling?> which is MUCH faster than dpmi_int.

I see....

>
>
> > >     The near pointer functions set the limit of a selector to a very high value.  NT sees this as a
> > > possible crashing program and does not allow it.  If NT did allow it, then it would be easier to make
> > > it (NT) crash.
> > anyway...i've got a question about selectors...well, perhaps a couple... i'd have to use _farpokeb do
> > access the .....selected memory right?...or movedata(..) to copy a buffer?
>
>     Yes.  I've made my own 'setdata' function to use a bunch of _farnspokel calls to quickly write a single
> value to a bunch of contiguous locations.

> > what exactly is: _my_ds()?
> > i know it's a selector and i know (to some degree..i don;t quite know how to make one yet...soon
> > though..) what a selector is... but...what is _my_ds()?
>
>     It is a function that returns the selector for the data in your program.  All variables dynamically or
> statically allocated will be within the scope of _my_ds().--

ahh..ok... thanks...

L8r,
      Merlin.