1 #include <linux/module.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 11 unsigned int hweight32(unsigned int w) 12 { 13 unsigned int res = (w & 0x55555555) + ((w >> 1) & 0x55555555); 14 res = (res & 0x33333333) + ((res >> 2) & 0x33333333); 15 res = (res & 0x0F0F0F0F) + ((res >> 4) & 0x0F0F0F0F); 16 res = (res & 0x00FF00FF) + ((res >> 8) & 0x00FF00FF); 17 return (res & 0x0000FFFF) + ((res >> 16) & 0x0000FFFF); 18 } 19 EXPORT_SYMBOL(hweight32); 20 21 unsigned int hweight16(unsigned int w) 22 { 23 unsigned int res = (w & 0x5555) + ((w >> 1) & 0x5555); 24 res = (res & 0x3333) + ((res >> 2) & 0x3333); 25 res = (res & 0x0F0F) + ((res >> 4) & 0x0F0F); 26 return (res & 0x00FF) + ((res >> 8) & 0x00FF); 27 } 28 EXPORT_SYMBOL(hweight16); 29 30 unsigned int hweight8(unsigned int w) 31 { 32 unsigned int res = (w & 0x55) + ((w >> 1) & 0x55); 33 res = (res & 0x33) + ((res >> 2) & 0x33); 34 return (res & 0x0F) + ((res >> 4) & 0x0F); 35 } 36 EXPORT_SYMBOL(hweight8); 37 38 unsigned long hweight64(__u64 w) 39 { 40 #if BITS_PER_LONG == 32 41 return hweight32((unsigned int)(w >> 32)) + hweight32((unsigned int)w); 42 #elif BITS_PER_LONG == 64 43 u64 res; 44 res = (w & 0x5555555555555555ul) + ((w >> 1) & 0x5555555555555555ul); 45 res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul); 46 res = (res & 0x0F0F0F0F0F0F0F0Ful) + ((res >> 4) & 0x0F0F0F0F0F0F0F0Ful); 47 res = (res & 0x00FF00FF00FF00FFul) + ((res >> 8) & 0x00FF00FF00FF00FFul); 48 res = (res & 0x0000FFFF0000FFFFul) + ((res >> 16) & 0x0000FFFF0000FFFFul); 49 return (res & 0x00000000FFFFFFFFul) + ((res >> 32) & 0x00000000FFFFFFFFul); 50 #else 51 #error BITS_PER_LONG not defined 52 #endif 53 } 54 EXPORT_SYMBOL(hweight64); 55