From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Wed, 15 Feb 2006 11:16:08 GMT
Subject: Re: [FYI] pack idx format
Message-ID: <Pine.LNX.4.63.0602151208181.9837@wbgn013.biozentrum.uni-wuerzburg.de>
In-Reply-To: <7vd5hpm2x0.fsf@assigned-by-dhcp.cox.net>

Hi,

On Wed, 15 Feb 2006, Junio C Hamano wrote:

> [...]
> 
> Before this main table, at the beginning of the idx file, there
> is a table of 256 4-byte network byte order integers.  This is
> called "first-level fan-out".  N-th entry of this table records
> the offset into the main index for the first object whose object
> name SHA1 starts with N+1.  fanout[255] points at the end of
> main index.  The offset is expressed in 24-bytes unit.

The description of the n-th entry is not completely correct. How about 
something like this:

The fan-out table is sort of an index to the main table: It contains 
offsets into the main table, and all SHA1s starting with byte b are 
between fanout[b-1] .. fanout[b]-1 (or if b==0 between 0 .. fanout[0]-1).

Comments?

Ciao,
Dscho