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From: dvljrt@cs.umu.se (Joakim Rosqvist)
Newsgroups: comp.sys.amiga.advocacy
Subject: Re: Short Hello World
Message-ID: <1991May5.094238.26014@cs.umu.se>
Date: 5 May 91 09:42:38 GMT
References: <1991Apr30.213936.22878@ux1.cso.uiuc.edu> <1991May2.102554.8679@cs.umu.se> <1991May5.011748.11595@zorch.SF-Bay.ORG>
Sender: news@cs.umu.se (News Administrator)
Organization: Dep. of Info.Proc, Umea Univ., Sweden
Lines: 40

In article <1991May5.011748.11595@zorch.SF-Bay.ORG> xanthian@zorch.SF-Bay.ORG (Kent Paul Dolan) writes:
>dvljrt@cs.umu.se (Joakim Rosqvist) writes:
>
>> [some boring C-code deleted]   :-)
>
>> Ok, assembler strikes back with this: (56 codesize, 92 executable)
>
>> OpenLib=-408
>> Output=-60
>> Write=-48
>
>>   move.l 4.w,a6
>>   lea    dos(pc),a1
>>   jsr    OpenLib(a6)
>>   move.l d0,a6
>>   jsr    Output(a6)
>>   move.l d0,d1
>>   lea    hello(pc),a0
>>   move.l a0,d2
>>   moveq  #12,d3
>>   jmp    write(a6)
>
>> dos:   dc 'dos.library',0
>> hello: dc 'Hello World',10
>
>> /$DR.HEX$
>
>And a better example of how _not_ to program would be hard to find.
>
>You've managed, in a 15 line program, to include 3 "magic numbers"
>that are dependent on the release of dos.library, so that your code
>need not merely be reassembled for an operating system upgrade, but
>rewritten. 

What!?! In my opinion I use only 1 "magic" number, The address 4, which
is blessed by Commodore. The 3 values you are talking about are index:es
in a jump-table, which remain the same with new releases. That's what
jump-tables are for, otherwise you could jump directly to a ROM-address
(which even I wouldn't do)
/$DR.HEX$