1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/export.h>
3 #include <linux/bitops.h>
4 #include <asm/types.h>
5 
6 /**
7  * hweightN - returns the hamming weight of a N-bit word
8  * @x: the word to weigh
9  *
10  * The Hamming Weight of a number is the total number of bits set in it.
11  */
12 
__sw_hweight32(unsigned int w)13 unsigned int __sw_hweight32(unsigned int w)
14 {
15 #ifdef CONFIG_ARCH_HAS_FAST_MULTIPLIER
16 	w -= (w >> 1) & 0x55555555;
17 	w =  (w & 0x33333333) + ((w >> 2) & 0x33333333);
18 	w =  (w + (w >> 4)) & 0x0f0f0f0f;
19 	return (w * 0x01010101) >> 24;
20 #else
21 	unsigned int res = w - ((w >> 1) & 0x55555555);
22 	res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
23 	res = (res + (res >> 4)) & 0x0F0F0F0F;
24 	res = res + (res >> 8);
25 	return (res + (res >> 16)) & 0x000000FF;
26 #endif
27 }
28 EXPORT_SYMBOL(__sw_hweight32);
29 
__sw_hweight16(unsigned int w)30 unsigned int __sw_hweight16(unsigned int w)
31 {
32 	unsigned int res = w - ((w >> 1) & 0x5555);
33 	res = (res & 0x3333) + ((res >> 2) & 0x3333);
34 	res = (res + (res >> 4)) & 0x0F0F;
35 	return (res + (res >> 8)) & 0x00FF;
36 }
37 EXPORT_SYMBOL(__sw_hweight16);
38 
__sw_hweight8(unsigned int w)39 unsigned int __sw_hweight8(unsigned int w)
40 {
41 	unsigned int res = w - ((w >> 1) & 0x55);
42 	res = (res & 0x33) + ((res >> 2) & 0x33);
43 	return (res + (res >> 4)) & 0x0F;
44 }
45 EXPORT_SYMBOL(__sw_hweight8);
46 
__sw_hweight64(__u64 w)47 unsigned long __sw_hweight64(__u64 w)
48 {
49 #if BITS_PER_LONG == 32
50 	return __sw_hweight32((unsigned int)(w >> 32)) +
51 	       __sw_hweight32((unsigned int)w);
52 #elif BITS_PER_LONG == 64
53 #ifdef CONFIG_ARCH_HAS_FAST_MULTIPLIER
54 	w -= (w >> 1) & 0x5555555555555555ul;
55 	w =  (w & 0x3333333333333333ul) + ((w >> 2) & 0x3333333333333333ul);
56 	w =  (w + (w >> 4)) & 0x0f0f0f0f0f0f0f0ful;
57 	return (w * 0x0101010101010101ul) >> 56;
58 #else
59 	__u64 res = w - ((w >> 1) & 0x5555555555555555ul);
60 	res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul);
61 	res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0Ful;
62 	res = res + (res >> 8);
63 	res = res + (res >> 16);
64 	return (res + (res >> 32)) & 0x00000000000000FFul;
65 #endif
66 #endif
67 }
68 EXPORT_SYMBOL(__sw_hweight64);
69