Messages in this thread | | | Date | Fri, 10 Aug 2012 14:08:24 -0700 (PDT) | Subject | Re: [PATCH] MPILIB: Provide count_leading/trailing_zeros() based on arch functions | From | David Miller <> |
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From: Jan Engelhardt <jengelh@inai.de> Date: Fri, 10 Aug 2012 14:51:49 +0200 (CEST)
> > On Saturday 2012-07-21 02:46, David Miller wrote: >>> Arnd Bergmann <arnd@arndb.de> wrote: >>> >>>> I don't generally like to put stuff into asm-generic when it's unlikely >>>> to be overridden by architectures. It would really belong into >>>> include/linux, but then again we have all the other bitops in asm-generic >>>> as well, so whatever... >>> >>> Some arches (such as Sparc, I think) have count-leading-zero instructions. >> >>Yes, newer sparc64 chips have leading-zero-detect, and I was pretty >>sure that powerpc had something similar. It's called count-leading- >>zeros or something like that. > > And gcc has a __builtin_clz.
Which I can't use. I have to patch the code at run time based upon whether the cpu has the 'lzd' instruction or not.
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