[Haskell-cafe] containers license issue

[Clark Gaebel]

Possibly. I tend to trust GHC's strictness analyzer until proven otherwise,
though. Feel free to optimize as necessary.

  - Clark


On Wed, Dec 12, 2012 at 3:06 PM, Vo Minh Thu <noteed at gmail.com> wrote:

> 2012/12/12 Johan Tibell <johan.tibell at gmail.com>:
> > On Wed, Dec 12, 2012 at 10:40 AM, Clark Gaebel <cgaebel at uwaterloo.ca>
> wrote:
> >> I just did a quick derivation from
> >> http://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2 to
> get
> >> the highest bit mask, and did not reference FXT nor the containers
> >> implementation. Here is my code:
> >>
> >> highestBitMask :: Word64 -> Word64
> >> highestBitMask x1 = let x2 = x1 .|. x1 `shiftR` 1
> >>                         x3 = x2 .|. x2 `shiftR` 2
> >>                         x4 = x3 .|. x3 `shiftR` 4
> >>                         x5 = x4 .|. x4 `shiftR` 8
> >>                         x6 = x5 .|. x5 `shiftR` 16
> >>                         x7 = x6 .|. x6 `shiftR` 32
> >>                      in x7 `xor` (x7 `shiftR` 1)
> >>
> >> This code is hereby released into the public domain. Problem solved.
> >
> > I will integrate this into containers later today.
>
> Note that I think the current implementation use a series of case
> expression instead of a let binding, possibly to force the evaluation.
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.haskell.org/pipermail/haskell-cafe/attachments/20121212/2c211414/attachment.htm>