Message-ID:	<33BB72C2.B1ADF07B@abc.se>
Date:	Thu, 03 Jul 1997 11:37:06 +0200
From:	Henrik Baarnhielm <Henrik DOT Baarnhielm AT abc DOT se>
MIME-Version:	1.0
To:	djgpp AT delorie DOT com
Subject:	Re: VESA 1.2

>>or is it possible to call the real-mode address from protected mode? >>If so how?
>
>You could use DPMI function 0x0301 (via the libc routine 
>__dpmi_simulate_real_mode_procedure_retf()), but there's no great
>advantage in using that over calling the real mode interrupt: both
>methods require the expensive mode switch. For fast graphics, VBE 2.0 >is the way to go...

I have succesfully made the above call, and it works and seemed to go
faster than the interrupt, but maybe it was only as it seemed.

I tried to get the pmode-bankswitch-functions with the VBE function 0ah.
I use bankswitch because my card doesn't have LFB, it has only VBE 1.2
built in. I also get a memoryaddress that I have to map. The VBE 2.0
specs says I should allocate a new descriptor and set it's address and
size to the values I got from the 0ah call and when I call the
pmode-bankswitch I should load ES with the descriptor. That is what I
don't know how to do?
I allocated a ldt with the libc-function __dpmi_allocate_ldt_descriptors
and set it's address and size with __dpmi_set_segment_base_address and
__dpmi_set_segment_limit and I locked the memory with
__dpmi_lock_linear_region.
But how do I put the ldt in ES before I call? I tried to use this inline
asm:
asm volatile("movw %%bx,%0
              movw %%dx,%1
              movw %$es,%2"
              :
              :"b" (temp),"d" (bank),"r" (ldt)
              :"%bx","%dx","$es");

but the compiler doesn't like es.
It would be nice if some of you Gurus could help me. I have been helped
by the Allegro-source a couple of times before, but not this time. I
couldn't even find any bankswitch-call.... your help would be
appreciated Shawn or any other of you Masters....

Thank you
-- 
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Internet : Henrik DOT Baarnhielm AT abc DOT se
Fidonet  : Henrik Baarnhielm, 2:201/235
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