From: Alex Riesen <raa.lkml@gmail.com>
Date: Thu, 27 May 2010 18:22:29 GMT
Subject: Re: Libgit2 on the Summer of Code
Message-ID: <AANLkTilE7UI3zg180U9GCB6DsByu3B9pwlG6xIyR8uiG@mail.gmail.com>
In-Reply-To: <20100527180554.GM16470@spearce.org>

On Thu, May 27, 2010 at 20:05, Shawn O. Pearce <spearce@spearce.org> wrote:
> Ilari Liusvaara <ilari.liusvaara@elisanet.fi> wrote:
>> * Where algorithm in git_revpool_table__hash() is from? Since it appears to
>> hash binary object IDs, wouldn't just simple sum/xor over words be sufficient
>> (all SHA-1 output bits are very nearly independent). Or do you need to be
>> compatible with some other implementation (doesn't appear so, because hash
>> is computed differently depending on endianess)?
>
> If you need a hash value for a SHA-1, why not just cast the unsigned
> char* to unsigned int* and load the first int as the hash code?
> The output of SHA-1 is pretty evenly distributed, using the first
> few bytes as an int should yield a sufficient distribution throughout
> the hashtable.

Just make sure the SHA1 data are properly aligned for your platform