From:	Endlisnis <s257m AT unb DOT ca>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: VESA: hints, clue but no examples
Date:	Sat, 22 Aug 1998 15:35:59 -0300
Organization:	NBTel Internet
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To:	djgpp AT delorie DOT com
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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.

> >     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().--
     (\/) Endlisnis (\/)
          s257m AT unb DOT ca
          Endlisnis AT GeoCities DOT com
          Endlis AT nbnet DOT nb DOT ca

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