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Path: utzoo!utcsri!greg
From: greg@utcsri.UUCP (Gregory Smith)
Newsgroups: net.lang.c
Subject: Re: icky C code
Message-ID: <3117@utcsri.UUCP>
Date: Thu, 17-Jul-86 15:00:11 EDT
Article-I.D.: utcsri.3117
Posted: Thu Jul 17 15:00:11 1986
Date-Received: Thu, 17-Jul-86 15:16:56 EDT
References: <2239@brl-smoke.ARPA> <2446@umcp-cs.UUCP>
Reply-To: greg@utcsri.UUCP (Gregory Smith)
Organization: CSRI, University of Toronto
Lines: 34
Summary: Fun with registers

In article <2446@umcp-cs.UUCP> chris@maryland.UUCP (Chris Torek) writes:
>>There is code which relies on ints and pointers being the same size.
>
>Alas, this seems to creep in everywhere---usually as a result of
>programmer laziness.  An imagined programming session:
>
>	/* Oops, gotta call getenv, but the declarations are all
>	   way above.  Enh, I won't bother declaring it. */
>	p = (char *) getenv("FOO");
>
>First, this is bad coding, like writing unnecessary LOOPHOLEs in Mesa.
>Second, lint will complain.  Third, it is not really all that hard to
>go put in the declaration.  Leave out the cast and even the compiler
>will complain, which will remind you to go clean up!
>
Fourth, it is not guaranteed to be portable. It will probably be a lot more
portable than it should be, though. Compiler implementors have gone to
surprising lengths to allow this sort of thing. From a code efficiency
standpoint, for example, a 68000 should return int's in D0 and all pointer
types in A0, which would break the above. ( Somebody pointed out that a
certain 68K compiler has an option to return both types in *both* regs ).
Or am I wrong, and there is a non-unwritten ( i.e. official ) rule that
says everything should return in the same reg whenever possible?

Imagine a library function ( coded in assembler ) which returns a useful
int value if declared int and a useful, different, pointer value if declared
as a pointer! ( not a serious suggestion, but would be feasible if the
same code were given two names ).

-- 
"You'll need more than a Tylenol if you don't tell me where my father is!"
						- The Ice Pirates
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Greg Smith     University of Toronto      UUCP: ..utzoo!utcsri!greg