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From: Vojtech Pavlik <vojtech@suse.cz>
To: Denis Vlasenko <vda@ilport.com.ua>
Cc: Grant Coady <grant_lkml@dodo.com.au>,
	Simon Evans <spse@secret.org.uk>,
	linux-kernel@vger.kernel.org
Subject: Re: New inventions in rounding up in catc.c?
Date: Sun, 25 Sep 2005 22:54:55 +0200	[thread overview]
Message-ID: <20050925205455.GA6747@midnight.ucw.cz> (raw)
In-Reply-To: <200509251343.47892.vda@ilport.com.ua>

On Sun, Sep 25, 2005 at 01:43:47PM +0300, Denis Vlasenko wrote:
> On Saturday 24 September 2005 21:46, Grant Coady wrote:
> > On Sat, 24 Sep 2005 13:43:42 +0300, Denis Vlasenko <vda@ilport.com.ua> wrote:
> > > 		/* F5U011 only does one packet per RX */
> > > 		if (catc->is_f5u011)
> > > 			break;
> > >-		pkt_start += (((pkt_len + 1) >> 6) + 1) << 6;
> > >+		pkt_start += ((pkt_len + 2) + 63) & ~63;
> > 
> >   		pkt_start += ((pkt_len + 1) + 64) & ~63;
> > 
> > Seems more clear to me.
> 
> Why?
> 
> ((pkt_len + 2) + 63) & ~63 is "add 2 and round up to next 64".
> ((pkt_len + 1) + 64) & ~63 is "???!"
> 
> It's strange code anyway, I hope maintainer can clarify what's going on.
> (I suspect it was intended to be pkt_len - 1, not +, in the first place)
 
Honestly, I don't remember at all. I'll try to find the (very old) docs
I have for the chip.

-- 
Vojtech Pavlik
SuSE Labs, SuSE CR

      reply	other threads:[~2005-09-25 20:55 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-09-24 10:43 New inventions in rounding up in catc.c? Denis Vlasenko
2005-09-24 18:46 ` Grant Coady
2005-09-25 10:43   ` Denis Vlasenko
2005-09-25 20:54     ` Vojtech Pavlik [this message]

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