libxfs/xfs_bit.h

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2000,2002,2005 Silicon Graphics, Inc.
   4  * All Rights Reserved.
   5  */
   6 #ifndef __XFS_BIT_H__
   7 #define __XFS_BIT_H__
   8
   9 /*
  10  * XFS bit manipulation routines.
  11  */
  12
  13 /*
  14  * masks with n high/low bits set, 64-bit values
  15  */
  16 static inline uint64_t xfs_mask64hi(int n)
  17 {
  18         return (uint64_t)-1 << (64 - (n));
  19 }
  20 static inline uint32_t xfs_mask32lo(int n)
  21 {
  22         return ((uint32_t)1 << (n)) - 1;
  23 }
  24 static inline uint64_t xfs_mask64lo(int n)
  25 {
  26         return ((uint64_t)1 << (n)) - 1;
  27 }
  28
  29 /* Get high bit set out of 32-bit argument, -1 if none set */
  30 static inline int xfs_highbit32(uint32_t v)
  31 {
  32         return fls(v) - 1;
  33 }
  34
  35 /* Get high bit set out of 64-bit argument, -1 if none set */
  36 static inline int xfs_highbit64(uint64_t v)
  37 {
  38         return fls64(v) - 1;
  39 }
  40
  41 /* Get low bit set out of 32-bit argument, -1 if none set */
  42 static inline int xfs_lowbit32(uint32_t v)
  43 {
  44         return ffs(v) - 1;
  45 }
  46
  47 /* Get low bit set out of 64-bit argument, -1 if none set */
  48 static inline int xfs_lowbit64(uint64_t v)
  49 {
  50         uint32_t        w = (uint32_t)v;
  51         int             n = 0;
  52
  53         if (w) {        /* lower bits */
  54                 n = ffs(w);
  55         } else {        /* upper bits */
  56                 w = (uint32_t)(v >> 32);
  57                 if (w) {
  58                         n = ffs(w);
  59                         if (n)
  60                                 n += 32;
  61                 }
  62         }
  63         return n - 1;
  64 }
  65
  66 /* Return whether bitmap is empty (1 == empty) */
  67 extern int xfs_bitmap_empty(uint *map, uint size);
  68
  69 /* Count continuous one bits in map starting with start_bit */
  70 extern int xfs_contig_bits(uint *map, uint size, uint start_bit);
  71
  72 /* Find next set bit in map */
  73 extern int xfs_next_bit(uint *map, uint size, uint start_bit);
  74
  75 #endif  /* __XFS_BIT_H__ */