Xref:	news2.mv.net comp.os.msdos.djgpp:4096
From:	Shawn Hargreaves <slh100 AT york DOT ac DOT uk>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Making the nearptr hacks use longs.
Date:	Tue, 21 May 1996 15:19:10 +0100
Organization:	The University of York, UK
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To:	djgpp AT delorie DOT com
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On Tue, 21 May 1996, Eli Zaretskii wrote:

> `dosmemputl' (and `movedata') already use 32-bit movsd, so I don't see 
> how you can get any real speed-up here.  The only situation where nearptr 
> is faster is when you operate on single pixels or small groups of 
> pixels.  If you need to move large buffers, `movedata' is as fast as 
> nearptr, but much more safe (as it doesn't disable memory protection), 
> and also works on any DPMI platform.

Absolutely. I think the only benefit of near pointers is ease of coding, not 
speed. Writing 'screen_addr[x+y*w] = color' is a lot easier and more 
flexible than calling the farptr functions, but I've yet to notice any 
major speed differences between the two. Even when writing single pixels 
(which is the worst case for far pointers, requiring a segment load per 
pixel), when I did a test program that timed a mode 13h putpixel both 
ways, I only got a 3% speed increase with nearptrs. Using more 
complicated graphics routines (lines, blits, etc) I couldn't detect any 
speed difference at all...


/*
 *	Shawn Hargreaves.        Why is 'phonetic' spelt with a ph?
 *	Check out Allegro and FED on http://www.york.ac.uk/~slh100/
 */

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