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From: chris@mimsy.umd.EDU (Chris Torek)
Newsgroups: comp.unix.questions
Subject: Re:  Teaching Assembler on VAX (BSD 4.3)
Message-ID: <7447@brl-adm.ARPA>
Date: Tue, 19-May-87 10:31:05 EDT
Article-I.D.: brl-adm.7447
Posted: Tue May 19 10:31:05 1987
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	From: Root Boy Jim <rbj@icst-cmr.ARPA>

	I don't have the original article, but maybe he meant "is it"
	[it being m4, the question being is it tailored to C] rather
	then "it is". I don't see m4 as being particularly tailored for or
	against C or assembly or anything else for that matter.

m4 is just about maximally untailored.

	   What makes an assembler friendly or unfriendly?

	I'm surprised you had to ask, Chris, or was that a rhetorical
	question?

No: I have never had much use for fancy macros in assembly.  All
I want from an assembler is that it assemble, quickly, and that it
tell me where something is wrong.  There is so little to go wrong
that it does not matter *what*: just *where*.

	I think [an extensive macro facility] is a major requirement
	for serious asm hacking. As a litmus test, I would say the
	ability to write a set of macros which implemented if-then-else,
	while, and the like (in short, a mini compiler), is a pretty
	good assembler.

I had never even considered using macros for higher level constructs.
When I wanted higher level contstructs, I used higher level languages.
(I thought that was what they were for...? :-) )

	In fact, I would rather use cpp for assembly as well. But
	perhaps m4 can generate multi-line text?

It does indeed.

Here is something that friend of mine whipped up yesterday while playing
with m4:

	define(for,`define'($1,$2)`ifelse($2,$3,$4
	,$4
	undefine(`$1')`for'($1,`incr'($2),$3,$4))')

	for(i,1,6,xxx(i) + i)

	define(pushall,`ifelse($1,,,push $1
	`pushall'($2,$3,$4,$5,$6,$7,$8,$9))')dnl

	pushall(a,b,c)

	define(popall, `ifelse($1,,,`popall'($2,$3,$4,$5,$6,$7,$8,$9)pop $1
	)')dnl

	popall(a,b,c)

Run on this, m4 produces the following (adjacent blank lines squished
out):

	xxx(1) + 1
	xxx(2) + 2
	xxx(3) + 3
	xxx(4) + 4
	xxx(5) + 5
	xxx(6) + 6

	push a
	push b
	push c

	pop c
	pop b
	pop a

Not particularly useful for anything, perhaps, but it does demonstrate
that m4 can do at least some of what those other macro facilities
can do.