1 // SPDX-License-Identifier: GPL-2.0 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 __sw_hweight32(unsigned int w)12unsigned 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 __sw_hweight16(unsigned int w)28unsigned 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 __sw_hweight8(unsigned int w)36unsigned 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 __sw_hweight64(__u64 w)43unsigned 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 } 64