sys/vfs/gnu/ext2fs/ext2_bitops.h

   1 /*-
   2  * Copyright (c) 2003 Marcel Moolenaar
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  *
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  *
  26  * $FreeBSD: src/sys/gnu/fs/ext2fs/ext2_bitops.h,v 1.3 2006/04/13 19:37:32 cracauer Exp $
  27  * $DragonFly: src/sys/vfs/gnu/ext2fs/ext2_bitops.h,v 1.1 2007/09/23 04:09:55 yanyh Exp $
  28  */
  29
  30 #ifndef _SYS_GNU_EXT2FS_EXT2_BITOPS_H_
  31 #define _SYS_GNU_EXT2FS_EXT2_BITOPS_H_
  32
  33 #define find_first_zero_bit(data, sz)           find_next_zero_bit(data, sz, 0)
  34
  35 static __inline int
  36 clear_bit(int no, void *data)
  37 {
  38         uint32_t *p;
  39         uint32_t mask, new, old;
  40
  41         p = (uint32_t*)data + (no >> 5);
  42         mask = (1U << (no & 31));
  43         do {
  44                 old = *p;
  45                 new = old & ~mask;
  46         } while (!atomic_cmpset_32(p, old, new));
  47         return (old & mask);
  48 }
  49
  50 static __inline int
  51 set_bit(int no, void *data)
  52 {
  53         uint32_t *p;
  54         uint32_t mask, new, old;
  55
  56         p = (uint32_t*)data + (no >> 5);
  57         mask = (1U << (no & 31));
  58         do {
  59                 old = *p;
  60                 new = old | mask;
  61         } while (!atomic_cmpset_32(p, old, new));
  62         return (old & mask);
  63 }
  64
  65 static __inline int
  66 test_bit(int no, void *data)
  67 {
  68         uint32_t *p;
  69         uint32_t mask;
  70
  71         p = (uint32_t*)data + (no >> 5);
  72         mask = (1U << (no & 31));
  73         return (*p & mask);
  74 }
  75
  76 static __inline size_t
  77 find_next_zero_bit(void *data, size_t sz, size_t ofs)
  78 {
  79         uint32_t *p;
  80         uint32_t mask;
  81         int bit;
  82
  83         p = (uint32_t*)data + (ofs >> 5);
  84         if (ofs & 31) {
  85                 mask = ~0U << (ofs & 31);
  86                 bit = *p | ~mask;
  87                 if (bit != ~0U)
  88                         return (ffs(~bit) + ofs - 1);
  89                 p++;
  90                 ofs = (ofs + 31U) & ~31U;
  91         }
  92         while(ofs < sz && *p == ~0U) {
  93                 p++;
  94                 ofs += 32;
  95         }
  96         if (ofs == sz)
  97                 return (ofs);
  98         bit = *p;
  99         return (ffs(~bit) + ofs - 1);
 100 }
 101
 102 static __inline void *
 103 memscan(void *data, int c, size_t sz)
 104 {
 105         uint8_t *p;
 106
 107         p = data;
 108         while (sz && *p != c) {
 109                 p++;
 110                 sz--;
 111         }
 112         return (p);
 113 }
 114
 115 #endif /* _SYS_GNU_EXT2FS_EXT2_BITOPS_H_ */