Messages in this thread |  | | | Date | Wed, 20 Oct 2004 12:53:53 +0200 | | From | Martin Zwickel <> | | Subject | Re: [PATCH (updated)] Avoid annoying build warning on 32-bit platforms |
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On Wed, 20 Oct 2004 03:23:43 -0700 Chris Wedgwood <cw@f00f.org> bubbled:
> On Wed, Oct 20, 2004 at 11:56:45AM +0200, Mikael Pettersson wrote: > > > There's a coding idiom for doing this: just break up > > the ">> 32" in two steps, like: ((time >> 31) >> 1). > > i assumed gcc would complain there too but it doesn't and it does > optimize this away (i checked) > > > Definitely preferable over #ifdef:s. > > indeed > > > > Avoid annoying gcc warning on 32-bit platforms. > > Signed-off-by: cw@f00f.org > > ===== drivers/char/random.c 1.57 vs edited ===== > --- 1.57/drivers/char/random.c 2004-10-05 14:21:53 -07:00 > +++ edited/drivers/char/random.c 2004-10-20 03:19:17 -07:00 > @@ -818,12 +818,10 @@ static void add_timer_randomness(struct > * jiffies. > */ > time = get_cycles(); > - if (time != 0) { > - if (sizeof(time) > 4) > - num ^= (u32)(time >> 32); > - } else { > + if (time) > + num ^= (u32)((time >> 32) >> 1); ^^ errr ... should be 31 ?!?! > + else > time = jiffies; > - } > > /* > * Calculate number of bits of randomness we probably added. > - > To unsubscribe from this list: send the line "unsubscribe > linux-kernel" in the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
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Martin Zwickel <martin.zwickel@technotrend.de> Research & Development
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