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Re: Exporting ffs32/ffs64

On Mon, Aug 03, 2009 at 03:53:43PM +0100, Mindaugas Rasiukevicius wrote:
> Hello,
> Joerg Sonnenberger <> wrote:
> > I am going to add support for ffsl and ffsll soon. One practical
> > question is whether we want to provide the fixed width versions (ffs32
> > and ffs64) in libc namespace or not. They can currently be obtained as
> > inline functions from sys/bitops.h and I don't see a strong reason to
> > not provide them.
> Exporting fixed width versions (ffs32 and ffs64) sound reasonable. Would all
> architectures support 64-bit version?

Yes. Default implementation of ffs64 for 32-bit archs will fallback to

> Why do you want to export ffsl and ffsll?

GNU compatibility. They are also provided as (optional?) builtins by
GCC. As with popcount, I consider the interface idiotic, but the cost of
supporting them is very low (two aliases).


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