Re: [PATCH] doc: technical details about the index file format

From: Joshua Juran <jjuran@gmail.com>
Date: Sep 2, 2010, 09:08 UTC
Message-ID: <E4DDD4F7-FEDB-49CE-9515-90D64B66D7D3@gmail.com>
In-Reply-To: <AANLkTi=wESk38u1XSTL1rd2__eQzHfSuq-EbqooxmcVw@mail.gmail.com>

On Sep 2, 2010, at 1:56 AM, Alex Riesen wrote:

Show 18 quoted lines

> 2010/9/1 Nguyễn Thái Ngọc Duy <pclouds@gmail.com>:
>> +== Index entry
>> +
>> +  Index entries are sorted in ascending order on the name field,
>> +  interpreted as a string of unsigned bytes. Entries with the same
>> +  name are sorted by their stage field.
>> +
>> +  32-bit ctime seconds, the last time a file's metadata changed
>> +    this is stat(2) data
>> +
>> +  32-bit ctime nanoseconds (modulo 1G)
>> +    this is stat(2) data
>
> Maybe I'm missing something, but I failed to find where "modulo 1G"  
> comes from.
> AFAICS (read-cache.c), the stat data are saved almost unmodified
> (casted to unsigned int).
> (BTW, is 1G the Gravitational Constant or what?)

G stands for "giga-" meaning one billion, so 1G refers to one billion nanoseconds.

> I'm not sure it is safe to assume that  every system Git will be
> ported to defines
> "unsigned int" to be 32 bits. OTOH, never met one where it is  
> something else.

DOS and early Mac compilers have used 16-bit ints, but I don't think anyone cares.

Josh