LXR linux/fs/xfs/xfs

   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 */
  28static inline __uint64_t xfs_mask64hi(int n)
  29{
  30        return (__uint64_t)-1 << (64 - (n));
  31}
  32static inline __uint32_t xfs_mask32lo(int n)
  33{
  34        return ((__uint32_t)1 << (n)) - 1;
  35}
  36static 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 */
  42static 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 */
  48static 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 */
  54static 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 */
  60static 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 && (n = ffs(w)))
  70                n += 32;
  71        }
  72        return n - 1;
  73}
  74
  75/* Return whether bitmap is empty (1 == empty) */
  76extern int xfs_bitmap_empty(uint *map, uint size);
  77
  78/* Count continuous one bits in map starting with start_bit */
  79extern int xfs_contig_bits(uint *map, uint size, uint start_bit);
  80
  81/* Find next set bit in map */
  82extern int xfs_next_bit(uint *map, uint size, uint start_bit);
  83
  84#endif  /* __XFS_BIT_H__ */
  85