lib/bitops.h

   1 /*
   2  *      BIRD Library -- Generic Bit Operations
   3  *
   4  *      (c) 1998 Martin Mares <mj@ucw.cz>
   5  *
   6  *      Can be freely distributed and used under the terms of the GNU GPL.
   7  */
   8
   9 #ifndef _BIRD_BITOPTS_H_
  10 #define _BIRD_BITOPTS_H_
  11
  12 #include "sysdep/config.h"
  13
  14 /*
  15  *      Bit mask operations:
  16  *
  17  *      u32_mkmask      Make bit mask consisting of <n> consecutive ones
  18  *                      from the left and the rest filled with zeroes.
  19  *                      E.g., u32_mkmask(5) = 0xf8000000.
  20  *      u32_masklen     Inverse operation to u32_mkmask, -1 if not a bitmask.
  21  */
  22
  23 u32 u32_mkmask(uint n);
  24 uint u32_masklen(u32 x);
  25
  26 u32 u32_log2(u32 v);
  27
  28 static inline u32 u32_hash(u32 v) { return v * 2902958171u; }
  29
  30 static inline u8 u32_popcount(u32 v) { return __builtin_popcount(v); }
  31 static inline u8 u64_popcount(u64 v) { return __builtin_popcountll(v); }
  32
  33 static inline int u32_clz(u32 v) { return __builtin_clz(v); }
  34 static inline int u32_ctz(u32 v) { return __builtin_ctz(v); }
  35
  36 static inline int uint_is_pow2(uint n) { return n && !(n & (n-1)); }
  37
  38 #endif