projects / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
| 0aefc359 ACM |
2 | #include <linux/bitops.h> |
| 3 | #include <asm/types.h> | |
| 4 | ||
| 5 | /** | |
| 6 | * hweightN - returns the hamming weight of a N-bit word | |
| 7 | * @x: the word to weigh | |
| 8 | * | |
| 9 | * The Hamming Weight of a number is the total number of bits set in it. | |
| 10 | */ | |
| 11 | ||
| 12 | unsigned int __sw_hweight32(unsigned int w) | |
| 13 | { | |
| 14 | #ifdef CONFIG_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; | |
| 19 | #else | |
| 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; | |
| 25 | #endif | |
| 26 | } | |
| 27 | ||
| 28 | unsigned int __sw_hweight16(unsigned int w) | |
| 29 | { | |
| 30 | unsigned int res = w - ((w >> 1) & 0x5555); | |
| 31 | res = (res & 0x3333) + ((res >> 2) & 0x3333); | |
| 32 | res = (res + (res >> 4)) & 0x0F0F; | |
| 33 | return (res + (res >> 8)) & 0x00FF; | |
| 34 | } | |
| 35 | ||
| 36 | unsigned int __sw_hweight8(unsigned int w) | |
| 37 | { | |
| 38 | unsigned int res = w - ((w >> 1) & 0x55); | |
| 39 | res = (res & 0x33) + ((res >> 2) & 0x33); | |
| 40 | return (res + (res >> 4)) & 0x0F; | |
| 41 | } | |
| 42 | ||
| 43 | unsigned long __sw_hweight64(__u64 w) | |
| 44 | { | |
| 45 | #if BITS_PER_LONG == 32 | |
| 46 | return __sw_hweight32((unsigned int)(w >> 32)) + | |
| 47 | __sw_hweight32((unsigned int)w); | |
| 48 | #elif BITS_PER_LONG == 64 | |
| 49 | #ifdef CONFIG_ARCH_HAS_FAST_MULTIPLIER | |
| 50 | w -= (w >> 1) & 0x5555555555555555ul; | |
| 51 | w = (w & 0x3333333333333333ul) + ((w >> 2) & 0x3333333333333333ul); | |
| 52 | w = (w + (w >> 4)) & 0x0f0f0f0f0f0f0f0ful; | |
| 53 | return (w * 0x0101010101010101ul) >> 56; | |
| 54 | #else | |
| 55 | __u64 res = w - ((w >> 1) & 0x5555555555555555ul); | |
| 56 | res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul); | |
| 57 | res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0Ful; | |
| 58 | res = res + (res >> 8); | |
| 59 | res = res + (res >> 16); | |
| 60 | return (res + (res >> 32)) & 0x00000000000000FFul; | |
| 61 | #endif | |
| 62 | #endif | |
| 63 | } |