Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!tank!mimsy!chris
From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.lang.c
Subject: Re: Conversion of unsigned long to double
Message-ID: <17110@mimsy.UUCP>
Date: 26 Apr 89 05:26:01 GMT
References: <515@bsiao.UUCP> <4612@freja.diku.dk>
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 24

In article <4612@freja.diku.dk> njk@freja.diku.dk (Niels J|rgen Kruse) writes:
>Lest you should harbour any delusions that the Bsd 4.3 cc
>handles unsigned arithmetic and conversions correctly in
>general, try running this little program :

>  if ((unsigned)-1 < 1) printf ("*splat*\n");
>  else printf ("correct.\n");

Fixed in 4.3-tahoe.  (Donn uncommented a cast within PCC itself that
had been disabled.)

>  printf ("Second test : the same value assigned to dblt[0] and dblt[1]\n");
>  dblt[i] = ut[2];
>  dblt[++i] = ut[2];

Oops!  The compiler is using the subscript addressing modes (-40(fp)[r1])
for both the jbsc (to test and clear the sign bit) and the addd2 (to add
2^31); but the latter multiplies r1 by 8, not 4, so it adds to the wrong
variable.

Might be fixed in 4.4 :-) ,
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris@mimsy.umd.edu	Path:	uunet!mimsy!chris