Re: CRC review

From: Daryle Walker (darylew_at_[hidden])
Date: 2001-03-15 20:00:28

on 3/14/01 7:52 AM, John Maddock at John_Maddock_at_[hidden] wrote:

[SNIP]
>> I don't think there are "standard" CRC parameters.  I picked the ones above
>> as examples because those were the examples used in the Internet papers I
>> read.  If I use other types, I would have to compute the "123456789"
>> reference CRC result by hand as a check; which isn't easy.  (I took about a
>> half-hour doing the 1-bit example that is in the test.)
> 
> That isn't the impression that I got - chosing the wrong parameters can
> lead to something that's not as strong as it should be - but maybe some
> else can jump in here.

There are some parameter sets that work better than others.  I was saying
that, within the restraints of quality, there is a lot of arbitrariness in
choosing CRC parameters.  The CRC computers can only be concerned with
executing in a good manner.  The user to generate, or find, good CRC
parameters on their own.  I'm not an expert, so I could be wrong on this.

[SNIP]
>> I hope you haven't reported that last bug.  If so, take it back.  It is not a
>> bug, because "<:" is a perfectly legitimate digraph!  It represents the
>> opening square bracket ("[").
> 
> Well well, you learn something new every day - just shows how few compilers
> support digraphs that only gcc (as far as I know) chokes over this.

My compiler supports digraphs.  That's why I always space my template
parameters.  (I discovered this the hard way when I tried to do "template X
<::std::size_t T>".)

-- 
Daryle Walker
Mac, Internet, and Video Game Junkie
darylew AT mac DOT com