1 #include <linux/export.h> 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 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 EXPORT_SYMBOL(__sw_hweight32); 28 29 unsigned int __sw_hweight16(unsigned int w) 30 { 31 unsigned int res = w - ((w >> 1) & 0x5555); 32 res = (res & 0x3333) + ((res >> 2) & 0x3333); 33 res = (res + (res >> 4)) & 0x0F0F; 34 return (res + (res >> 8)) & 0x00FF; 35 } 36 EXPORT_SYMBOL(__sw_hweight16); 37 38 unsigned int __sw_hweight8(unsigned int w) 39 { 40 unsigned int res = w - ((w >> 1) & 0x55); 41 res = (res & 0x33) + ((res >> 2) & 0x33); 42 return (res + (res >> 4)) & 0x0F; 43 } 44 EXPORT_SYMBOL(__sw_hweight8); 45 46 unsigned long __sw_hweight64(__u64 w) 47 { 48 #if BITS_PER_LONG == 32 49 return __sw_hweight32((unsigned int)(w >> 32)) + 50 __sw_hweight32((unsigned int)w); 51 #elif BITS_PER_LONG == 64 52 #ifdef ARCH_HAS_FAST_MULTIPLIER 53 w -= (w >> 1) & 0x5555555555555555ul; 54 w = (w & 0x3333333333333333ul) + ((w >> 2) & 0x3333333333333333ul); 55 w = (w + (w >> 4)) & 0x0f0f0f0f0f0f0f0ful; 56 return (w * 0x0101010101010101ul) >> 56; 57 #else 58 __u64 res = w - ((w >> 1) & 0x5555555555555555ul); 59 res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul); 60 res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0Ful; 61 res = res + (res >> 8); 62 res = res + (res >> 16); 63 return (res + (res >> 32)) & 0x00000000000000FFul; 64 #endif 65 #endif 66 } 67 EXPORT_SYMBOL(__sw_hweight64); 68