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Date:      Tue, 05 Apr 2005 23:33:30 -0500
From:      Jon Noack <noackjr@alumni.rice.edu>
To:        Matthew Dillon <dillon@apollo.backplane.com>
Cc:        Jeremie Le Hen <jeremie@le-hen.org>
Subject:   Re: strcspn(3) complexity improvement
Message-ID:  <4253669A.1060704@alumni.rice.edu>
In-Reply-To: <200504060346.j363ko4b088610@apollo.backplane.com>
References:  <20050330083435.GI75546@obiwan.tataz.chchile.org> <20050330183145.GB24465@odin.ac.hmc.edu> <200504060346.j363ko4b088610@apollo.backplane.com>

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On 04/05/05 22:46, Matthew Dillon wrote:
> :The real question I have is, how long does the string need to be before
> :this is a win and how much does it hurt for typical string lengths?
> :I've written code with strcspn that needed to perform well, but it was
> :parsing 80-column punch card derived formats.
> :
> :-- Brooks
> 
>      I think the answer is to not use strcspn() in cases where it *really*
>      matters.
> 
>      I don't think what's in DFly is the right solution either.  A bitmap
>      would be a good compromise, though... that would only require clearing
>      32 bytes (vs 256) at the cost of slowing down the loop a little.

The version das@ committed used one bit per element:
http://lists.freebsd.org/pipermail/cvs-src/2005-April/044040.html

Jon



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