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