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From: babraham@Daisy.EE.UND.AC.ZA (Bobby Abraham)
Newsgroups: comp.lang.lisp
Subject: Help needed - Read Macros
Keywords: lisp
Message-ID: <1991Jun13.064841.20364@Daisy.EE.UND.AC.ZA>
Date: 13 Jun 91 06:48:41 GMT
Organization: Univ. Natal, Durban, S. Africa
Lines: 29


I am needing some help with the following problem in an simple
assembler I am writing.

I wish to parse expressions such as
     mov  #10 20
     add  @13 #6
  l: jmp  @5
 
Ideally I would like a lexical analyser to return the following
        mov (immediate 10) 20
    	add (indirect 13) (immediate 6)
     	(label l) jmp (indirect 5)

I know that # will cause the lisp reader to dispatch a macro but
this is no problem as one can (substitute #\! #\# input-line).

I suspect that it may be possible to do this by defining read macros
although it may be necessary to specify labels in the form :label rather
than label:

Any help would be gratefully received?

Many thanks. 

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-=-=-=
Bobby Abraham
Dept of Computer Science, University of Natal, Pietermaritzburg
babraham@daisy.ee.und.ac.za