Line data    Source code

       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           0 : 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           0 :         unsigned int res = w - ((w >> 1) & 0x55555555);
      22           0 :         res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
      23           0 :         res = (res + (res >> 4)) & 0x0F0F0F0F;
      24           0 :         res = res + (res >> 8);
      25           0 :         return (res + (res >> 16)) & 0x000000FF;
      26             : #endif
      27             : }
      28             : EXPORT_SYMBOL(__sw_hweight32);
      29             : 
      30           0 : unsigned int __sw_hweight16(unsigned int w)
      31             : {
      32           0 :         unsigned int res = w - ((w >> 1) & 0x5555);
      33           0 :         res = (res & 0x3333) + ((res >> 2) & 0x3333);
      34           0 :         res = (res + (res >> 4)) & 0x0F0F;
      35           0 :         return (res + (res >> 8)) & 0x00FF;
      36             : }
      37             : EXPORT_SYMBOL(__sw_hweight16);
      38             : 
      39           0 : unsigned int __sw_hweight8(unsigned int w)
      40             : {
      41           0 :         unsigned int res = w - ((w >> 1) & 0x55);
      42           0 :         res = (res & 0x33) + ((res >> 2) & 0x33);
      43           0 :         return (res + (res >> 4)) & 0x0F;
      44             : }
      45             : EXPORT_SYMBOL(__sw_hweight8);
      46             : 
      47           4 : 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           4 :         __u64 res = w - ((w >> 1) & 0x5555555555555555ul);
      60           4 :         res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul);
      61           4 :         res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0Ful;
      62           4 :         res = res + (res >> 8);
      63           4 :         res = res + (res >> 16);
      64           4 :         return (res + (res >> 32)) & 0x00000000000000FFul;
      65             : #endif
      66             : #endif
      67             : }
      68             : EXPORT_SYMBOL(__sw_hweight64);