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From: apratt@atari.UUCP (Allan Pratt)
Newsgroups: comp.sys.atari.st
Subject: Re: assemblers
Message-ID: <1480@atari.UUCP>
Date: 4 May 89 19:39:41 GMT
References: <1837@blake.acs.washington.edu> <534@TSfR.UUCP> <99@sdcc10.ucsd.EDU>
Reply-To: apratt@atari.UUCP (Allan Pratt)
Organization: Atari (US) Corporation, Sunnyvale, California
Lines: 42

In article <99@sdcc10.ucsd.EDU> cs163afu@sdcc10.ucsd.edu.UUCP (Some call me...Tim) writes:
> MadMac in the Atari Developer's kit, for one reason:  Speed.

You betcha.

> And if you really want it optimized--after you have it running, use
> the Alcyon assembler at that point.  They are completely code
> compatible.

They are NOT completely compatible.  It is possible to write code
which assembles the same (modulo optimizations) under both assemblers.
However, MadMac is more strict on some points (colon after label,
semicolon before comment) and AS68 doesn't have macros.  Furthermore,
the syntax for conditional assembly is totally different, and
the behavior of "=" and "set" and "equ" might be different.

MadMac has an option (-6) which lets you assemble Alcyon compiler
output.  It is NOT an AS68 compatibility mode; it is a C68 back-end
mode.  It simply ignores lines beginning with "~" and does some other
things (I forget what). 

You can ask MadMac to inform you of unoptimized short branches, so you
can go back and put ".s" on them. 

AS68 doesn't know about the XXXX.w addressing mode: 

	INPUT	      MadMac output	        AS68 output
	------------  ------------------------  --------------------------
	lea $1234,a0  lea $1234.w,a0 (2 words)  lea $00001234,a0 (3 words)


Lastly, AS68 makes at least one illegal optimization.  Assuming that a
missing size modifier means the same as .w, the optimization

	move #1,d0	-->	moveq.l #1,d0

which AS68 does is illegal.  MadMac does moveq, addq, and subq
optimization correctly.

============================================
Opinions expressed above do not necessarily	-- Allan Pratt, Atari Corp.
reflect those of Atari Corp. or anyone else.	  ...ames!atari!apratt