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, 32-bit values & 64-bit values
  27  */
  28 #define XFS_MASK32HI(n)         xfs_mask32hi(n)
  29 static inline __uint32_t xfs_mask32hi(int n)
  30 {
  31         return (__uint32_t)-1 << (32 - (n));
  32 }
  33 #define XFS_MASK64HI(n)         xfs_mask64hi(n)
  34 static inline __uint64_t xfs_mask64hi(int n)
  35 {
  36         return (__uint64_t)-1 << (64 - (n));
  37 }
  38 #define XFS_MASK32LO(n)         xfs_mask32lo(n)
  39 static inline __uint32_t xfs_mask32lo(int n)
  40 {
  41         return ((__uint32_t)1 << (n)) - 1;
  42 }
  43 #define XFS_MASK64LO(n)         xfs_mask64lo(n)
  44 static inline __uint64_t xfs_mask64lo(int n)
  45 {
  46         return ((__uint64_t)1 << (n)) - 1;
  47 }
  48
  49 /* Get high bit set out of 32-bit argument, -1 if none set */
  50 static inline int xfs_highbit32(__uint32_t v)
  51 {
  52         return fls(v) - 1;
  53 }
  54
  55 /* Get high bit set out of 64-bit argument, -1 if none set */
  56 static inline int xfs_highbit64(__uint64_t v)
  57 {
  58         return fls64(v) - 1;
  59 }
  60
  61 /* Get low bit set out of 32-bit argument, -1 if none set */
  62 static inline int xfs_lowbit32(__uint32_t v)
  63 {
  64         unsigned long   t = v;
  65         return (v) ? find_first_bit(&t, 32) : -1;
  66 }
  67
  68 /* Get low bit set out of 64-bit argument, -1 if none set */
  69 static inline int xfs_lowbit64(__uint64_t v)
  70 {
  71         __uint32_t      w = (__uint32_t)v;
  72         int             n = 0;
  73
  74         if (w) {        /* lower bits */
  75                 n = ffs(w);
  76         } else {        /* upper bits */
  77                 w = (__uint32_t)(v >> 32);
  78                 if (w && (n = ffs(w)))
  79                 n += 32;
  80         }
  81         return n - 1;
  82 }
  83
  84 /* Return whether bitmap is empty (1 == empty) */
  85 extern int xfs_bitmap_empty(uint *map, uint size);
  86
  87 /* Count continuous one bits in map starting with start_bit */
  88 extern int xfs_contig_bits(uint *map, uint size, uint start_bit);
  89
  90 /* Find next set bit in map */
  91 extern int xfs_next_bit(uint *map, uint size, uint start_bit);
  92
  93 #endif  /* __XFS_BIT_H__ */