Sender:	nate AT cartsys DOT com
Message-ID:	<36197680.DA3F2536@cartsys.com>
Date:	Mon, 05 Oct 1998 18:46:40 -0700
From:	Nate Eldredge <nate AT cartsys DOT com>
X-Mailer:	Mozilla 4.05 [en] (X11; I; Linux 2.0.35 i486)
MIME-Version:	1.0
To:	James Dominy <jdominy AT saturn DOT cs DOT unp DOT ac DOT za>
CC:	djgpp AT delorie DOT com
Subject:	Re: Writing Drivers?
References:	<907589267 DOT 988799 AT mars DOT cs DOT unp DOT ac DOT za>
Reply-To:	djgpp AT delorie DOT com

James Dominy wrote:
> 
> Right I've got two putpixel routines, one for VESA 1.2 banked mode, the
> other for VESA 2.0 Linear Frame Buffer Mode.
> 
> They are both implemented as macros now for speed purposes, although no
> doubt inline would have much the same effect on performance.
> 
> However, I do not want to continuously have if statements all over my code
> checking which routine should be used. So, I set up an array as such
> 
> void *putpixel[2](int x, int y, int c);
> 
> and call putpixel[0](0,0,15) for example or use 1 instead of 0 for the
> second routine.
> 
> But can I inline them in any way? I realize that this would involve the
> compiler knowing which routine would be used on each call, but I would know
> that from after my mode setting routine!

Probably not: if the function's address has to come from a variable, it
*will* go through a function call mechanism, and won't be inlined.

A good idea might be to use an algorithm that doesn't involve putpixel,
but rather writes to a buffer and then blits it to the screen.
-- 

Nate Eldredge
nate AT cartsys DOT com

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