Hi,
[auto build test ERROR on v4.6-rc5]
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url:
https://github.com/0day-ci/linux/commits/zengzhaoxiu-163-com/lib-GCD-add-binary-GCD-algorithm/20160428-195527
config
> __ffs on the available architectures:
> Alpha: sometimes (CONFIG_ALPHA_EV6, CONFIG_ALPHA_EV67)
> ARC: sometimes (!CONFIG_ISA_ARCOMPACT)
> ARM: sometimes (V5+)
> ARM64: NO, could be written using RBIT and CLZ
> AVR: yes
> Blackfin: NO, could be written using hwe
> How does a CPU lack an efficient ffs/ctz anyway? There are all sorts
> of ways to implement it without a native insn, some of which are
> almost or just as fast as the native insn on cpus that have the
> latter. On anything with a fast multiply, the de Bruijn sequence
> approach is near-optimal,
On Thu, Apr 28, 2016 at 7:58 PM, Rich Felker wrote:
> On Thu, Apr 28, 2016 at 07:51:06PM +0200, Geert Uytterhoeven wrote:
>> On Thu, Apr 28, 2016 at 6:48 PM, George Spelvin wrote:
>> > Another few comments:
>> >
>> > 1. Would ARCH_HAS_FAST_FFS involve fewer changes than CPU_NO_EFFICIENT_FFS?
>>
>
On Thu, Apr 28, 2016 at 07:51:06PM +0200, Geert Uytterhoeven wrote:
> On Thu, Apr 28, 2016 at 6:48 PM, George Spelvin wrote:
> > Another few comments:
> >
> > 1. Would ARCH_HAS_FAST_FFS involve fewer changes than CPU_NO_EFFICIENT_FFS?
>
> No, as you want to _disable_ ARCH_HAS_FAST_FFS / _enable_
On Thu, Apr 28, 2016 at 6:48 PM, George Spelvin wrote:
> Another few comments:
>
> 1. Would ARCH_HAS_FAST_FFS involve fewer changes than CPU_NO_EFFICIENT_FFS?
No, as you want to _disable_ ARCH_HAS_FAST_FFS / _enable_
CPU_NO_EFFICIENT_FFS as soon as you're enabling support for a
CPU that doesn't s
On Thu, 2016-04-28 at 19:43 +0800, zengzhao...@163.com wrote:
> From: Zhaoxiu Zeng
>
> Because some architectures (alpha, armv6, etc.) don't provide
> hardware division, the mod operation is slow! Binary GCD algorithm
> uses simple arithmetic operations, it replaces division with
> arithmetic
Another few comments:
1. Would ARCH_HAS_FAST_FFS involve fewer changes than CPU_NO_EFFICIENT_FFS?
Rather than updating all the Kconfig files, it could be #defined in
the arch/*/asm/bitops.h files where the __ffs macro is defined. E.g.
diff --git a/arch/alpha/include/asm/bitops.h b/arch
On Apr 28, 2016, at 7:43 AM, zengzhao...@163.com wrote:
> + * This implements the binary GCD algorithm. (Often attributed to Stein,
> + * but as Knuth has noted, appears a first-century Chinese math text.)
Should this be "appears in a"?
Josh
Hi,
[auto build test ERROR on v4.6-rc5]
[cannot apply to next-20160428]
[if your patch is applied to the wrong git tree, please drop us a note to help
improving the system]
url:
https://github.com/0day-ci/linux/commits/zengzhaoxiu-163-com/lib-GCD-add-binary-GCD-algorithm/20160428-195527
conf
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