LXR uboot/include/linux/bitops.h

   1#ifndef _LINUX_BITOPS_H
   2#define _LINUX_BITOPS_H
   3
   4
   5/*
   6 * ffs: find first bit set. This is defined the same way as
   7 * the libc and compiler builtin ffs routines, therefore
   8 * differs in spirit from the above ffz (man ffs).
   9 */
  10
  11static inline int generic_ffs(int x)
  12{
  13        int r = 1;
  14
  15        if (!x)
  16                return 0;
  17        if (!(x & 0xffff)) {
  18                x >>= 16;
  19                r += 16;
  20        }
  21        if (!(x & 0xff)) {
  22                x >>= 8;
  23                r += 8;
  24        }
  25        if (!(x & 0xf)) {
  26                x >>= 4;
  27                r += 4;
  28        }
  29        if (!(x & 3)) {
  30                x >>= 2;
  31                r += 2;
  32        }
  33        if (!(x & 1)) {
  34                x >>= 1;
  35                r += 1;
  36        }
  37        return r;
  38}
  39
  40/*
  41 * hweightN: returns the hamming weight (i.e. the number
  42 * of bits set) of a N-bit word
  43 */
  44
  45static inline unsigned int generic_hweight32(unsigned int w)
  46{
  47        unsigned int res = (w & 0x55555555) + ((w >> 1) & 0x55555555);
  48        res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
  49        res = (res & 0x0F0F0F0F) + ((res >> 4) & 0x0F0F0F0F);
  50        res = (res & 0x00FF00FF) + ((res >> 8) & 0x00FF00FF);
  51        return (res & 0x0000FFFF) + ((res >> 16) & 0x0000FFFF);
  52}
  53
  54static inline unsigned int generic_hweight16(unsigned int w)
  55{
  56        unsigned int res = (w & 0x5555) + ((w >> 1) & 0x5555);
  57        res = (res & 0x3333) + ((res >> 2) & 0x3333);
  58        res = (res & 0x0F0F) + ((res >> 4) & 0x0F0F);
  59        return (res & 0x00FF) + ((res >> 8) & 0x00FF);
  60}
  61
  62static inline unsigned int generic_hweight8(unsigned int w)
  63{
  64        unsigned int res = (w & 0x55) + ((w >> 1) & 0x55);
  65        res = (res & 0x33) + ((res >> 2) & 0x33);
  66        return (res & 0x0F) + ((res >> 4) & 0x0F);
  67}
  68
  69#include <asm/bitops.h>
  70
  71
  72#endif
  73