[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>
This commit is contained in:
parent
09020adb61
commit
3b9ed1a5d2
|
@ -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_ */
|
|
@ -23,6 +23,7 @@ lib-$(CONFIG_RWSEM_GENERIC_SPINLOCK) += rwsem-spinlock.o
|
||||||
lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o
|
lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o
|
||||||
lib-$(CONFIG_SEMAPHORE_SLEEPERS) += semaphore-sleepers.o
|
lib-$(CONFIG_SEMAPHORE_SLEEPERS) += semaphore-sleepers.o
|
||||||
lib-$(CONFIG_GENERIC_FIND_NEXT_BIT) += find_next_bit.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_LOCK_KERNEL) += kernel_lock.o
|
||||||
obj-$(CONFIG_DEBUG_PREEMPT) += smp_processor_id.o
|
obj-$(CONFIG_DEBUG_PREEMPT) += smp_processor_id.o
|
||||||
|
|
||||||
|
|
|
@ -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);
|
Loading…
Reference in New Issue