Path: utzoo!attcan!uunet!ginosko!uakari.primate.wisc.edu!ames!uhccux!munnari.oz.au!cs.mu.oz.au!ok
From: ok@cs.mu.oz.au (Richard O'Keefe)
Newsgroups: comp.lang.c,comp.sys.super
Subject: Re: Type punning in C
Message-ID: <2325@munnari.oz.au>
Date: 8 Oct 89 07:10:54 GMT
References: <475@idacrd.UUCP>
Sender: news@cs.mu.oz.au
Lines: 16

In article <475@idacrd.UUCP>, desj@idacrd.UUCP (David desJardins) writes:
>    Does anyone have any ideas on how one should go about converting an
> integer to the floating-point number with the same bit pattern?

	union { long i; float x; } pun;
	pun.i = the_integer_to_be_converted;
	the_single_precision_result = pun.f;

> One frequently (well, occasionally) needs to do this to implement certain
> bit manipulations efficiently on Cray computers and other vector machines ...

Just which operations are these?  If the operations are meaningful functions
of floating-point numbers (e.g. things like ilogb() copysign() nextafter())
it might make more sense to ask Cray to put _those_ in their library.

I really would like to know what the operations are.