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From: mt87692@tut.fi (Mikko Tsokkinen)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Assembler Programming - Costs versus Benefits
Message-ID: <MT87692.90Nov30211512@uikku.tut.fi>
Date: 30 Nov 90 20:15:12 GMT
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In-Reply-To: dolf@idca.tds.PHILIPS.nl's message of 30 Nov 90 07:38:19 GMT



> Could you please give details about the User instructions (i.e. instructions
> which can be made when running in User mode, not Supervisory mode) which
> behave differently on a 68000 and a 68020 [or 68030] ? I think only
> "move from SR" now traps but the OS should take care of this.

> <"but those aren't correct 68000 programs", which is all well and good but in
> <the real world these instructions exist and are percieved as being useful to
> <the sorts of folks who write manic games in assembler.

> Aha, one difference might be that these guys are writing self modifying code
> which may not work on a 680[234]0 as the changes go into the data cache not the
> main memory or instruction cache.

 90% of all games I have ever seen for amiga doesn't run with faster
processors because the disk loader and other waiting is badly written. 
They use wait loops like this:

wait	move.l	#2000,d0
	dbra.s	d0,wait

And this the absolutely same code as comes from c-compiler when you use similar
wait tactics. It seems too hard for 90% of programmers (on any language) to
use CIA timers. On the other hand the assembler programs are more likely to
crash because most of c-programs are written using the OS and the waiting is
done using the OS functions (this can done as easily with assembler).

 But it's very true that c-sources are much portable. The assambler is not
ment to be portable because the nature of assembler (direct processor
commands). Binaries in any language is just as unportable.

 MIT

--
Bubble Bobble