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author | Akinobu Mita <mita@miraclelinux.com> | 2006-03-26 01:39:13 -0800 |
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committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-03-26 08:57:11 -0800 |
commit | 3b9ed1a5d2d121f32d2cb4f2b05f1fc57c99c946 (patch) | |
tree | d8ea52d6b490c0e3b3851e1887c01700cc0115c6 | |
parent | 09020adb61416c4307de35941a9725a5e33d9beb (diff) | |
download | kernel_samsung_aries-3b9ed1a5d2d121f32d2cb4f2b05f1fc57c99c946.zip kernel_samsung_aries-3b9ed1a5d2d121f32d2cb4f2b05f1fc57c99c946.tar.gz kernel_samsung_aries-3b9ed1a5d2d121f32d2cb4f2b05f1fc57c99c946.tar.bz2 |
[PATCH] bitops: generic hweight{64,32,16,8}()
This patch introduces the C-language equivalents of the functions below:
unsigned int hweight32(unsigned int w);
unsigned int hweight16(unsigned int w);
unsigned int hweight8(unsigned int w);
unsigned long hweight64(__u64 w);
In include/asm-generic/bitops/hweight.h
This code largely copied from: include/linux/bitops.h
Signed-off-by: Akinobu Mita <mita@miraclelinux.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r-- | include/asm-generic/bitops/hweight.h | 9 | ||||
-rw-r--r-- | lib/Makefile | 1 | ||||
-rw-r--r-- | lib/hweight.c | 54 |
3 files changed, 64 insertions, 0 deletions
diff --git a/include/asm-generic/bitops/hweight.h b/include/asm-generic/bitops/hweight.h new file mode 100644 index 0000000..8be6f17 --- /dev/null +++ b/include/asm-generic/bitops/hweight.h @@ -0,0 +1,9 @@ +#ifndef _ASM_GENERIC_BITOPS_HWEIGHT_H_ +#define _ASM_GENERIC_BITOPS_HWEIGHT_H_ + +extern unsigned int hweight32(unsigned int w); +extern unsigned int hweight16(unsigned int w); +extern unsigned int hweight8(unsigned int w); +extern unsigned long hweight64(__u64 w); + +#endif /* _ASM_GENERIC_BITOPS_HWEIGHT_H_ */ diff --git a/lib/Makefile b/lib/Makefile index f827e3c..b830c9a 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -23,6 +23,7 @@ lib-$(CONFIG_RWSEM_GENERIC_SPINLOCK) += rwsem-spinlock.o lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o lib-$(CONFIG_SEMAPHORE_SLEEPERS) += semaphore-sleepers.o lib-$(CONFIG_GENERIC_FIND_NEXT_BIT) += find_next_bit.o +lib-$(CONFIG_GENERIC_HWEIGHT) += hweight.o obj-$(CONFIG_LOCK_KERNEL) += kernel_lock.o obj-$(CONFIG_DEBUG_PREEMPT) += smp_processor_id.o diff --git a/lib/hweight.c b/lib/hweight.c new file mode 100644 index 0000000..721a4b8 --- /dev/null +++ b/lib/hweight.c @@ -0,0 +1,54 @@ +#include <linux/module.h> +#include <asm/types.h> + +/** + * hweightN - returns the hamming weight of a N-bit word + * @x: the word to weigh + * + * The Hamming Weight of a number is the total number of bits set in it. + */ + +unsigned int hweight32(unsigned int w) +{ + unsigned int res = (w & 0x55555555) + ((w >> 1) & 0x55555555); + res = (res & 0x33333333) + ((res >> 2) & 0x33333333); + res = (res & 0x0F0F0F0F) + ((res >> 4) & 0x0F0F0F0F); + res = (res & 0x00FF00FF) + ((res >> 8) & 0x00FF00FF); + return (res & 0x0000FFFF) + ((res >> 16) & 0x0000FFFF); +} +EXPORT_SYMBOL(hweight32); + +unsigned int hweight16(unsigned int w) +{ + unsigned int res = (w & 0x5555) + ((w >> 1) & 0x5555); + res = (res & 0x3333) + ((res >> 2) & 0x3333); + res = (res & 0x0F0F) + ((res >> 4) & 0x0F0F); + return (res & 0x00FF) + ((res >> 8) & 0x00FF); +} +EXPORT_SYMBOL(hweight16); + +unsigned int hweight8(unsigned int w) +{ + unsigned int res = (w & 0x55) + ((w >> 1) & 0x55); + res = (res & 0x33) + ((res >> 2) & 0x33); + return (res & 0x0F) + ((res >> 4) & 0x0F); +} +EXPORT_SYMBOL(hweight8); + +unsigned long hweight64(__u64 w) +{ +#if BITS_PER_LONG == 32 + return hweight32((unsigned int)(w >> 32)) + hweight32((unsigned int)w); +#elif BITS_PER_LONG == 64 + u64 res; + res = (w & 0x5555555555555555ul) + ((w >> 1) & 0x5555555555555555ul); + res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul); + res = (res & 0x0F0F0F0F0F0F0F0Ful) + ((res >> 4) & 0x0F0F0F0F0F0F0F0Ful); + res = (res & 0x00FF00FF00FF00FFul) + ((res >> 8) & 0x00FF00FF00FF00FFul); + res = (res & 0x0000FFFF0000FFFFul) + ((res >> 16) & 0x0000FFFF0000FFFFul); + return (res & 0x00000000FFFFFFFFul) + ((res >> 32) & 0x00000000FFFFFFFFul); +#else +#error BITS_PER_LONG not defined +#endif +} +EXPORT_SYMBOL(hweight64); |