From: William Djaja Tjokroaminata <billtj@...>
Date: 2002-10-17T09:05:14+09:00
Subject: Re: Porting a CRC function to ruby

Hi Matthew,

I think in Ruby it is for efficiency purpose.  Ruby internal C
implementation distinguishes objects (which are represented as VALUE,
which is an alias for unsigned long) as either a pointer or an immediate
object.  Fixnum, which is an immediate object, is not allocated on Ruby gc
heap, so it is "cheaper" to deal with Fixnum's; the only cost is that
Fixnum is now only 31-bit significant instead of full 32-bit significant.

You can also browse -talk starting at 53043 regarding the left shift and
the least significant bit.

Regards,

Bill
============================================================================
Matthew Miller <namille2@vt.edu> wrote:
> Thanks for the insight. I tried my suggestion of masking off all but the 
> lower two bytes and the CRC works with the packets I've tested it with. 
> Still I wish that ruby had an unsigned integer class.

> BTW, why does Fixnum left shift by one the integer it stores? I can't think 
> of any reason why that would be done.