From: Jeff King <peff@peff.net>
Date: Thu, 10 Jul 2014 03:53:28 GMT
Subject: Re: move detection doesnt take filename into account
Message-ID: <20140710035328.GB28401@sigill.intra.peff.net>
In-Reply-To: <xmqqa98i9nwc.fsf@gitster.dls.corp.google.com>

On Wed, Jul 09, 2014 at 03:18:43PM -0700, Junio C Hamano wrote:

> Jeff King <peff@peff.net> writes:
> 
> > I think the hash here does not collide in that way. It really is just
> > the last sixteen characters shoved into a uint32_t.
> 
> All bytes overlap with their adjacent byte because they are shifted
> by only 2 bits, not 8 bits, when a new byte is brought in.  We can
> say that the topmost two bits of the result must have come from the
> last character, but other than these, there are more than one input
> byte for each bit position to be set/unset by, so two names that human
> would not consider "similar" would be given the same hash, no?

Yeah, you're right. I didn't look at the algorithm closely enough.

-Peff