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
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
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
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
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
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