Date: Mon, 28 Jul 1997 21:48:36 -0700 (PDT)
Message-Id: <199707290448.VAA13860@adit.ap.net>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
To: tcho AT polbox DOT com
From: Nate Eldredge <eldredge AT ap DOT net>
Subject: Re: Mem mapped device questions
Cc: djgpp AT delorie DOT com
Precedence: bulk

At 11:07  7/27/1997 +0200, you wrote:
>I understand that DJGPP v2 is DPMI only environment
>and such mapping is not possible but I have question:
>Is the access to memory mapped device limited only by that
>hardware or by the compiler also - that is:
>
>should the access to memory mapped device be faster/slower or
>the same comparing DJGPP v1 and DJGPP v2.
If you use the standard farptr (farpeek/farpoke) family of functions, it may
be slower due to the overhead of reloading the segment register each time.
Then again, it may not. :-) YMMV. If that isn't fast enough, you can use
either the no-selector farptr functions (farnspeek/farnspoke) which are safe
but only work in tight loops without function calls, or
__djgpp_nearptr_enable, which is more flexible but more dangerous and less
portable.

>P.S.
>I am sorry for my bad English
I think your English is very good.


Nate Eldredge
eldredge AT ap DOT net