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From: Charles Sandmann <sandmann AT clio DOT rice DOT edu>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Best way to access Vesa linear FB and mouse int handling?
Date: Thu, 07 Dec 1995 14:19:47 CST
Organization: Rice University, Houston, Texas
Lines: 17
References: <DJ6L1w DOT B1F AT jade DOT mv DOT net>
Reply-To: sandmann AT clio DOT rice DOT edu
Nntp-Posting-Host: clio.rice.edu
To: djgpp AT sun DOT soe DOT clarkson DOT edu
Dj-Gateway: from newsgroup comp.os.msdos.djgpp

> In the FAQ they give a method for wrapping a protected mode function with a 
> real mode callback function as a solution for driving the mouse---does this
> also apply for DJGPP 2.0? 

Yes, this is a DPMI function.  Be aware that all the code and data in your
RMCB routine should be locked.  See the docs for 
_go32_dpmi_allocate_real_mode_callback_retf

> Also, does anyone have a method for setting up a segment selector
> which points to a contiguous video memory buffer so I can unload all the
> expensive paging operations that go on every time I plot a pixel?

ftp.neosoft.com:pub/users/s/sandmann/vbe.zip shows how to access a VBE 2.0
linear frame buffer as a normal array in memory.  The farptr code can be
built with V2B3, but to use the nearptr version you need to wait for B4
to get the non-moving sbrk() so you don't need to reload the pointer.
Can't get much faster than accessing it as memory.