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path: root/include/asm-generic/bitops/const_hweight.h
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2014-02-09bitops: Fix signedness of compile-time hweight implementationsPaul Walmsley
Enabling '-Wsign-compare' compiler warnings on code that includes include/linux/bitops.h can generate the following warning: In file included from include/linux/kernel.h:10:0, from <random filename>:48: include/linux/bitops.h: In function 'hweight_long': include/linux/bitops.h:77:26: error: signed and unsigned type in conditional expression [-Werror=sign-compare] (converted to an error with -Werror) This is due to the use of the logical negation operator '!' in the __const_hweight8 macro in include/asm-generic/bitops/const_hweight.h. The use of that operator here results in a signed value. Fix by explicitly casting the __const_hweight8 macro expansion to 'unsigned int'. While here, clean up several checkpatch.pl warnings. Signed-off-by: Paul Walmsley <pwalmsley@nvidia.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1312180459580.30198@tamien Signed-off-by: Ingo Molnar <mingo@kernel.org>
2010-04-06bitops: Optimize hweight() by making use of compile-time evaluationPeter Zijlstra
Rename the extisting runtime hweight() implementations to __arch_hweight(), rename the compile-time versions to __const_hweight() and then have hweight() pick between them. Suggested-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <20100318111929.GB11152@aftab> Acked-by: H. Peter Anvin <hpa@zytor.com> LKML-Reference: <1265028224.24455.154.camel@laptop> Signed-off-by: H. Peter Anvin <hpa@zytor.com>