Path: utzoo!utgpu!water!watmath!clyde!rutgers!ames!ucsd!sdcsvax!nosc!humu!uhccux!lee
From: lee@uhccux.UUCP (Greg Lee)
Newsgroups: comp.lang.misc
Subject: Re: Languages and learning (was: Philosophy of C)
Summary: readable assembly language
Message-ID: <1534@uhccux.UUCP>
Date: 7 Feb 88 16:31:08 GMT
References: <11348@brl-adm.ARPA> <3473@ihlpf.ATT.COM> <3487@ihlpf.ATT.COM> <3555@ihlpf.ATT.COM> <670@l.cc.purdue.edu> <3579@ihlpf.ATT.COM>
Reply-To: lee@uhccux.uhcc.hawaii.edu (Greg Lee)
Organization: U. of Hawaii, Manoa (Honolulu)
Lines: 63

In article <3579@ihlpf.ATT.COM> nevin1@ihlpf.UUCP (00704a-Liber,N.J.) writes:
>In article <670@l.cc.purdue.edu> cik@l.cc.purdue.edu (Herman Rubin) writes:
>.
>.Most assembly languages are prenex, that is, the instruction comes first. This
>.is what makes assembly difficult to read and write.  The assembler language,
>....
>.programmer.  Now in HLLs we _declare_ the "type" assigned to that location.
>...
>First off, changing all the MOV statements to 'X = Y' do have reprocussions:
>the language would have to be 'compiled', not 'assembled', since I no longer
>know what statements are actually being executed.  If I need to do
>time-sensitive operations, your language is out because I need to get to the
>hardware instructions (but assembler is supposed to represent 1:1 the hardware
>instructions).
>...

A way to gain some of the readability of HLL's without giving up
the transparent semantics of assembly language is to use a preprocessing
translator with the properties:

	(1) legal assembly statements will be passed through
	    unaffected to the assembler, so that one can still
	    write in real assembly language, or partially in real
	    assembly language, when clarity demands this, and
	(2) the text transformations performed by the preprocessor
	    are sufficiently elementary that one can perform them
	    mentally if need be, to understand the import of a
	    piece of code.

I have such a tool for my Amiga, and I find it very helpful.  Here's
an example:

	define  snail  D1.B
	define  clips  D2.B
	byte    memvar
	byte    verf

	clips  =  memvar
	snail  =  clips
	snail  ?  verf
	!= {
		memvar += snail
	}

In the output file, the proprocessor produces:

 move.b .0001Q,D2
 move.b D2,D1
 cmp.b .0002Q,D1
 beq .0001
 add.b D1,.0001Q
.0001
.8001
   ...
 section webroom,bss
   ...
.0001Q DS.B 1
.0002Q DS.B 1
   ...
 end


Greg, lee@uhccux.uhcc.hawaii.edu