Please implement `fxreverse-bit-field'

[Andreas Rottmann]

Attached is a patch that adds a simple (and slow) implementation of `fxreverse-bit-field', using the algorithm from <http://graphics.stanford.edu/~seander/bithacks.html#BitReverseObvious>. Unfortunatly, my low-level Ikarus hacking skills didn't suffice to implement one of the smarter solutions from that page.

(FWIW, `fxreverse-bit-field' is used by the Huffmann coder in Göran's industria library collection).

[leppie (leppie)]

@rotty: Dont you think UNLESS would work better than those crazy nested IF's ?

[Abdulaziz Ghuloum (aghuloum)]

On Oct 2, 2009, at 7:51 PM, leppie wrote:

> @rotty: Dont you think UNLESS would work better than those crazy
> nested
> IF's ?

I think he's just following the style that's already there. It's all
my fault.

Aziz,,,

[Andreas Rottmann (rotty)]

leppie <email address hidden> writes:

> @rotty: Dont you think UNLESS would work better than those crazy nested
> IF's ?
>
I tried to follow the style of the existing code in the patch. I assume
Aziz had a reason to write it that way, but I don't know what that
reason would be. I agree that a version using `unless' would be more
readable.

[Gwen Weinholt (weinholt)]

I've written and attached an fxreverse-bit-field that does not loop if the system uses 61-bit or 30-bit fixnums. You can probably remove the loop for Ikarus (and it's not a very good loop anyway).

[Marco Maggi (mrc-mgg)]

Matched by Vicare issue 6, implemented using Goran's patch. Goran is it fine for you?

[Gwen Weinholt (weinholt)]

Marco Maggi <email address hidden> writes:

> Matched by Vicare issue 6, implemented using Goran's patch. Goran is it
> fine for you?

Sure.

--
Göran Weinholt <email address hidden>
"The gods confound the man who first found out how to distinguish the hours!
Confound him, too, who in this place set up a sundial, to cut and hack
my day so wretchedly into small pieces!" -- Titus Maccius Plautus, 200 BC