1 #include <linux/export.h>
2 #include <linux/bitops.h>
6 * hweightN - returns the hamming weight of a N-bit word
7 * @x: the word to weigh
9 * The Hamming Weight of a number is the total number of bits set in it.
12 unsigned int __sw_hweight32(unsigned int w
)
14 #ifdef ARCH_HAS_FAST_MULTIPLIER
15 w
-= (w
>> 1) & 0x55555555;
16 w
= (w
& 0x33333333) + ((w
>> 2) & 0x33333333);
17 w
= (w
+ (w
>> 4)) & 0x0f0f0f0f;
18 return (w
* 0x01010101) >> 24;
20 unsigned int res
= w
- ((w
>> 1) & 0x55555555);
21 res
= (res
& 0x33333333) + ((res
>> 2) & 0x33333333);
22 res
= (res
+ (res
>> 4)) & 0x0F0F0F0F;
23 res
= res
+ (res
>> 8);
24 return (res
+ (res
>> 16)) & 0x000000FF;
27 EXPORT_SYMBOL(__sw_hweight32
);
29 unsigned int __sw_hweight16(unsigned int w
)
31 unsigned int res
= w
- ((w
>> 1) & 0x5555);
32 res
= (res
& 0x3333) + ((res
>> 2) & 0x3333);
33 res
= (res
+ (res
>> 4)) & 0x0F0F;
34 return (res
+ (res
>> 8)) & 0x00FF;
36 EXPORT_SYMBOL(__sw_hweight16
);
38 unsigned int __sw_hweight8(unsigned int w
)
40 unsigned int res
= w
- ((w
>> 1) & 0x55);
41 res
= (res
& 0x33) + ((res
>> 2) & 0x33);
42 return (res
+ (res
>> 4)) & 0x0F;
44 EXPORT_SYMBOL(__sw_hweight8
);
46 unsigned long __sw_hweight64(__u64 w
)
48 #if BITS_PER_LONG == 32
49 return __sw_hweight32((unsigned int)(w
>> 32)) +
50 __sw_hweight32((unsigned int)w
);
51 #elif BITS_PER_LONG == 64
52 #ifdef ARCH_HAS_FAST_MULTIPLIER
53 w
-= (w
>> 1) & 0x5555555555555555ul
;
54 w
= (w
& 0x3333333333333333ul
) + ((w
>> 2) & 0x3333333333333333ul
);
55 w
= (w
+ (w
>> 4)) & 0x0f0f0f0f0f0f0f0ful
;
56 return (w
* 0x0101010101010101ul
) >> 56;
58 __u64 res
= w
- ((w
>> 1) & 0x5555555555555555ul
);
59 res
= (res
& 0x3333333333333333ul
) + ((res
>> 2) & 0x3333333333333333ul
);
60 res
= (res
+ (res
>> 4)) & 0x0F0F0F0F0F0F0F0Ful
;
61 res
= res
+ (res
>> 8);
62 res
= res
+ (res
>> 16);
63 return (res
+ (res
>> 32)) & 0x00000000000000FFul
;
67 EXPORT_SYMBOL(__sw_hweight64
);
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