Path: utzoo!utgpu!water!watmath!clyde!ima!johnl
Newsgroups: comp.compilers
Subject: Re: Simplistic Assemblers?
Summary: Unix assembler found unusable on real project
Message-ID: <842@ima.ISC.COM>
Date: 5 Jan 88 18:49:23 GMT
References: <789@ima.ISC.COM>
Sender: johnl@ima.ISC.COM
Reply-To: watmath!attila!arlie (Arlie Stephens)
Organization: Rohde&Schwarz Inc. Ottawa Canada
Lines: 73
Approved: compilers@ima.UUCP

In article <789@ima.ISC.COM> <ames!oliveb!edge!doug> writes:
>I would like to take a moment to dispute the
>claims made here about simplistic assemblers being better for the human
>assembler language programmer than complex assemblers.
> <....lots of detail omitted....>
>
I agree with this poster, and disagree with all the people who've
responded with things like:
	What you really need is a good macro processor SEPERATE from the 
		assembler.
	For example, 'M4' is wonderful, and does everything an 
		assembler programmer can possibly want.

This is absurd. I've had the misfortune of porting 68010 assembler 
programs from a Motorola development system (with a 'real' assembler)
to the Sun Unix environment (with Sun's Unix 'assembler' and M4).

(The reason for this was budget; management wanted all development on 
the same system, and couldn't at first see why we should pay for a real
assembler when we had one that came with Unix. The TARGET system remained
the same.)

M4 is NOT a full function macro processor. 

My biggest problem was that it doesn't know how to translate a character 
into its ascii value. We had a convention of storing strings as a sequence 
of characters with the high bit set on the last character. Strings were 
defined by a macro. How do you write that macro in M4 ? (Yes, there IS 
a kludge around...not a nice one.)

This was not the only missing function !

M4 is not integrated with the assembler. How do I force a string 
(in the data segment or bss, not the text segment) to start on a word
or long word boundary, when the assembler has no alignment directive
available (except in the text segment) ? 

And then there's the problem of an assembler that's designed to assemble
only the output of a C compiler, not ordinary human generated assembler.
It is NOT fun to have the assembler fail to detect your typos, and
generate semi-random code. I could cope with an assembler which lacks
explanatory error messages, if it would at least catch all my errors !
I could not cope with the Sun assembler, which I understand is a typical 
Unix assembler, possibly better than some of the others.

Management eventually accepted my recommendation that they buy a real
assembler for the Sun...it cost much less than the time I was wasting
wrestling with Sun's assembler.

In all fairness: this was a purchased program, written in an environment
where macro facilities were taken for granted. If I'd been writing it 
from scratch ON THE SUN I would have used C style strings, in spite of 
the extra memory, and I wouldn't have made data structures dependent 
on word alignment. Similarly, I would have designed around all the other
problems. But then, poor tools have always placed arbitrary restrictions
on program design !

I don't think having M4 seperate from the assembler was the real cause
of any of my problems. It exacerbated the weaknesses of both tools by 
making it impossible for them to support each other. (Assembler programmers
frequently write macros to replace missing assembler directives like
'place this point at a page boundary'; include a good selection of
assembler directives and integration won't be needed.)

				Arlie Stephens
				Don't try to reply; this account dies today.
[Unless people have other actual interesting experience to report, we can
probably consider this topic finished.  -John]
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