From: Philipp Meier <meier@...>
Date: 2002-08-31T00:37:25+09:00
Subject: Re: Pure Ruby implementation of CRC32?


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On Fri, Aug 30, 2002 at 09:54:54PM +0900, Park Heesob wrote:

> "Robert Feldt" <feldt@ce.chalmers.se> wrote in message
> news:Pine.GSO.4.44.0208301404310.28565-100000@duquesne.ce.chalmers.se...
>=20
> Try this
>=20
> def crc32(c)
>     n =3D c.length
>     r =3D 0xFFFFFFFF
>     n.times do |i|
>         r ^=3D c[i]
>         8.times do
>             if (r & 1)!=3D0
>                 r =3D (r>>1) ^ 0xEDB88320
>             else
>                 r >>=3D 1
>             end
>         end
>     end
>     r ^ 0xFFFFFFFF
> end

Or (more rubyish)

def crc32(c)
    r =3D 0xFFFFFFFF
    c.each_byte do |b|
        r ^=3D b
        8.times do
          r =3D (r>>1) ^ (0xEDB88320 * (r & 1))
        end
    end
    r ^ 0xFFFFFFFF
end

-billy.

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