fs/xfs/xfs_bit.h

   1 /*
   2  * Copyright (c) 2000,2002,2005 Silicon Graphics, Inc.
   3  * All Rights Reserved.
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it would be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write the Free Software Foundation,
  16  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17  */
  18 #ifndef __XFS_BIT_H__
  19 #define __XFS_BIT_H__
  20
  21 /*
  22  * XFS bit manipulation routines.
  23  */
  24
  25 /*
  26  * masks with n high/low bits set, 64-bit values
  27  */
  28 static inline __uint64_t xfs_mask64hi(int n)
  29 {
  30         return (__uint64_t)-1 << (64 - (n));
  31 }
  32 static inline __uint32_t xfs_mask32lo(int n)
  33 {
  34         return ((__uint32_t)1 << (n)) - 1;
  35 }
  36 static inline __uint64_t xfs_mask64lo(int n)
  37 {
  38         return ((__uint64_t)1 << (n)) - 1;
  39 }
  40
  41 /* Get high bit set out of 32-bit argument, -1 if none set */
  42 static inline int xfs_highbit32(__uint32_t v)
  43 {
  44         return fls(v) - 1;
  45 }
  46
  47 /* Get high bit set out of 64-bit argument, -1 if none set */
  48 static inline int xfs_highbit64(__uint64_t v)
  49 {
  50         return fls64(v) - 1;
  51 }
  52
  53 /* Get low bit set out of 32-bit argument, -1 if none set */
  54 static inline int xfs_lowbit32(__uint32_t v)
  55 {
  56         return ffs(v) - 1;
  57 }
  58
  59 /* Get low bit set out of 64-bit argument, -1 if none set */
  60 static inline int xfs_lowbit64(__uint64_t v)
  61 {
  62         __uint32_t      w = (__uint32_t)v;
  63         int             n = 0;
  64
  65         if (w) {        /* lower bits */
  66                 n = ffs(w);
  67         } else {        /* upper bits */
  68                 w = (__uint32_t)(v >> 32);
  69                 if (w) {
  70                         n = ffs(w);
  71                         if (n)
  72                                 n += 32;
  73                 }
  74         }
  75         return n - 1;
  76 }
  77
  78 /* Return whether bitmap is empty (1 == empty) */
  79 extern int xfs_bitmap_empty(uint *map, uint size);
  80
  81 /* Count continuous one bits in map starting with start_bit */
  82 extern int xfs_contig_bits(uint *map, uint size, uint start_bit);
  83
  84 /* Find next set bit in map */
  85 extern int xfs_next_bit(uint *map, uint size, uint start_bit);
  86
  87 #endif  /* __XFS_BIT_H__ */