fs/xfs/xfs_bit.c

   1 /*
   2  * Copyright (c) 2000-2005 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 #include "xfs.h"
  19 #include "xfs_bit.h"
  20 #include "xfs_log.h"
  21 #include "xfs_trans.h"
  22 #include "xfs_buf_item.h"
  23
  24 /*
  25  * XFS bit manipulation routines, used in non-realtime code.
  26  */
  27
  28 <<<<<<< HEAD:fs/xfs/xfs_bit.c
  29 =======
  30 #ifndef HAVE_ARCH_HIGHBIT
  31 /*
  32  * Index of high bit number in byte, -1 for none set, 0..7 otherwise.
  33  */
  34 static const char xfs_highbit[256] = {
  35        -1, 0, 1, 1, 2, 2, 2, 2,                 /* 00 .. 07 */
  36         3, 3, 3, 3, 3, 3, 3, 3,                 /* 08 .. 0f */
  37         4, 4, 4, 4, 4, 4, 4, 4,                 /* 10 .. 17 */
  38         4, 4, 4, 4, 4, 4, 4, 4,                 /* 18 .. 1f */
  39         5, 5, 5, 5, 5, 5, 5, 5,                 /* 20 .. 27 */
  40         5, 5, 5, 5, 5, 5, 5, 5,                 /* 28 .. 2f */
  41         5, 5, 5, 5, 5, 5, 5, 5,                 /* 30 .. 37 */
  42         5, 5, 5, 5, 5, 5, 5, 5,                 /* 38 .. 3f */
  43         6, 6, 6, 6, 6, 6, 6, 6,                 /* 40 .. 47 */
  44         6, 6, 6, 6, 6, 6, 6, 6,                 /* 48 .. 4f */
  45         6, 6, 6, 6, 6, 6, 6, 6,                 /* 50 .. 57 */
  46         6, 6, 6, 6, 6, 6, 6, 6,                 /* 58 .. 5f */
  47         6, 6, 6, 6, 6, 6, 6, 6,                 /* 60 .. 67 */
  48         6, 6, 6, 6, 6, 6, 6, 6,                 /* 68 .. 6f */
  49         6, 6, 6, 6, 6, 6, 6, 6,                 /* 70 .. 77 */
  50         6, 6, 6, 6, 6, 6, 6, 6,                 /* 78 .. 7f */
  51         7, 7, 7, 7, 7, 7, 7, 7,                 /* 80 .. 87 */
  52         7, 7, 7, 7, 7, 7, 7, 7,                 /* 88 .. 8f */
  53         7, 7, 7, 7, 7, 7, 7, 7,                 /* 90 .. 97 */
  54         7, 7, 7, 7, 7, 7, 7, 7,                 /* 98 .. 9f */
  55         7, 7, 7, 7, 7, 7, 7, 7,                 /* a0 .. a7 */
  56         7, 7, 7, 7, 7, 7, 7, 7,                 /* a8 .. af */
  57         7, 7, 7, 7, 7, 7, 7, 7,                 /* b0 .. b7 */
  58         7, 7, 7, 7, 7, 7, 7, 7,                 /* b8 .. bf */
  59         7, 7, 7, 7, 7, 7, 7, 7,                 /* c0 .. c7 */
  60         7, 7, 7, 7, 7, 7, 7, 7,                 /* c8 .. cf */
  61         7, 7, 7, 7, 7, 7, 7, 7,                 /* d0 .. d7 */
  62         7, 7, 7, 7, 7, 7, 7, 7,                 /* d8 .. df */
  63         7, 7, 7, 7, 7, 7, 7, 7,                 /* e0 .. e7 */
  64         7, 7, 7, 7, 7, 7, 7, 7,                 /* e8 .. ef */
  65         7, 7, 7, 7, 7, 7, 7, 7,                 /* f0 .. f7 */
  66         7, 7, 7, 7, 7, 7, 7, 7,                 /* f8 .. ff */
  67 };
  68 #endif
  69
  70 /*
  71  * xfs_highbit32: get high bit set out of 32-bit argument, -1 if none set.
  72  */
  73 inline int
  74 xfs_highbit32(
  75         __uint32_t      v)
  76 {
  77 #ifdef HAVE_ARCH_HIGHBIT
  78         return highbit32(v);
  79 #else
  80         int             i;
  81
  82         if (v & 0xffff0000)
  83                 if (v & 0xff000000)
  84                         i = 24;
  85                 else
  86                         i = 16;
  87         else if (v & 0x0000ffff)
  88                 if (v & 0x0000ff00)
  89                         i = 8;
  90                 else
  91                         i = 0;
  92         else
  93                 return -1;
  94         return i + xfs_highbit[(v >> i) & 0xff];
  95 #endif
  96 }
  97
  98 /*
  99  * xfs_lowbit64: get low bit set out of 64-bit argument, -1 if none set.
 100  */
 101 int
 102 xfs_lowbit64(
 103         __uint64_t      v)
 104 {
 105         __uint32_t      w = (__uint32_t)v;
 106         int             n = 0;
 107
 108         if (w) {        /* lower bits */
 109                 n = ffs(w);
 110         } else {        /* upper bits */
 111                 w = (__uint32_t)(v >> 32);
 112                 if (w && (n = ffs(w)))
 113                         n += 32;
 114         }
 115         return n - 1;
 116 }
 117
 118 /*
 119  * xfs_highbit64: get high bit set out of 64-bit argument, -1 if none set.
 120  */
 121 int
 122 xfs_highbit64(
 123         __uint64_t      v)
 124 {
 125         __uint32_t      h = (__uint32_t)(v >> 32);
 126
 127         if (h)
 128                 return xfs_highbit32(h) + 32;
 129         return xfs_highbit32((__uint32_t)v);
 130 }
 131
 132
 133 >>>>>>> 264e3e889d86e552b4191d69bb60f4f3b383135a:fs/xfs/xfs_bit.c
 134 /*
 135  * Return whether bitmap is empty.
 136  * Size is number of words in the bitmap, which is padded to word boundary
 137  * Returns 1 for empty, 0 for non-empty.
 138  */
 139 int
 140 xfs_bitmap_empty(uint *map, uint size)
 141 {
 142         uint i;
 143         uint ret = 0;
 144
 145         for (i = 0; i < size; i++) {
 146                 ret |= map[i];
 147         }
 148
 149         return (ret == 0);
 150 }
 151
 152 /*
 153  * Count the number of contiguous bits set in the bitmap starting with bit
 154  * start_bit.  Size is the size of the bitmap in words.
 155  */
 156 int
 157 xfs_contig_bits(uint *map, uint size, uint start_bit)
 158 {
 159         uint * p = ((unsigned int *) map) + (start_bit >> BIT_TO_WORD_SHIFT);
 160         uint result = 0;
 161         uint tmp;
 162
 163         size <<= BIT_TO_WORD_SHIFT;
 164
 165         ASSERT(start_bit < size);
 166         size -= start_bit & ~(NBWORD - 1);
 167         start_bit &= (NBWORD - 1);
 168         if (start_bit) {
 169                 tmp = *p++;
 170                 /* set to one first offset bits prior to start */
 171                 tmp |= (~0U >> (NBWORD-start_bit));
 172                 if (tmp != ~0U)
 173                         goto found;
 174                 result += NBWORD;
 175                 size -= NBWORD;
 176         }
 177         while (size) {
 178                 if ((tmp = *p++) != ~0U)
 179                         goto found;
 180                 result += NBWORD;
 181                 size -= NBWORD;
 182         }
 183         return result - start_bit;
 184 found:
 185         return result + ffz(tmp) - start_bit;
 186 }
 187
 188 /*
 189  * This takes the bit number to start looking from and
 190  * returns the next set bit from there.  It returns -1
 191  * if there are no more bits set or the start bit is
 192  * beyond the end of the bitmap.
 193  *
 194  * Size is the number of words, not bytes, in the bitmap.
 195  */
 196 int xfs_next_bit(uint *map, uint size, uint start_bit)
 197 {
 198         uint * p = ((unsigned int *) map) + (start_bit >> BIT_TO_WORD_SHIFT);
 199         uint result = start_bit & ~(NBWORD - 1);
 200         uint tmp;
 201
 202         size <<= BIT_TO_WORD_SHIFT;
 203
 204         if (start_bit >= size)
 205                 return -1;
 206         size -= result;
 207         start_bit &= (NBWORD - 1);
 208         if (start_bit) {
 209                 tmp = *p++;
 210                 /* set to zero first offset bits prior to start */
 211                 tmp &= (~0U << start_bit);
 212                 if (tmp != 0U)
 213                         goto found;
 214                 result += NBWORD;
 215                 size -= NBWORD;
 216         }
 217         while (size) {
 218                 if ((tmp = *p++) != 0U)
 219                         goto found;
 220                 result += NBWORD;
 221                 size -= NBWORD;
 222         }
 223         return -1;
 224 found:
 225         return result + ffs(tmp) - 1;
 226 }