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