source/lib/bitmap.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    simple bitmap functions
   4    Copyright (C) Andrew Tridgell 1992-1998
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 #include "includes.h"
  21
  22 /* these functions provide a simple way to allocate integers from a
  23    pool without repetition */
  24
  25 /****************************************************************************
  26 allocate a bitmap of the specified size
  27 ****************************************************************************/
  28 struct bitmap *bitmap_allocate(int n)
  29 {
  30         struct bitmap *bm;
  31
  32         bm = SMB_MALLOC_P(struct bitmap);
  33
  34         if (!bm) return NULL;
  35
  36         bm->n = n;
  37         bm->b = SMB_MALLOC_ARRAY(uint32, (n+31)/32);
  38         if (!bm->b) {
  39                 SAFE_FREE(bm);
  40                 return NULL;
  41         }
  42
  43         memset(bm->b, 0, sizeof(uint32)*((n+31)/32));
  44
  45         return bm;
  46 }
  47
  48 /****************************************************************************
  49 free a bitmap.
  50 ****************************************************************************/
  51
  52 void bitmap_free(struct bitmap *bm)
  53 {
  54         if (!bm)
  55                 return;
  56
  57         SAFE_FREE(bm->b);
  58         SAFE_FREE(bm);
  59 }
  60
  61 /****************************************************************************
  62 talloc a bitmap
  63 ****************************************************************************/
  64 struct bitmap *bitmap_talloc(TALLOC_CTX *mem_ctx, int n)
  65 {
  66         struct bitmap *bm;
  67
  68         if (!mem_ctx) return NULL;
  69
  70         bm = TALLOC_P(mem_ctx, struct bitmap);
  71
  72         if (!bm) return NULL;
  73
  74         bm->n = n;
  75         bm->b = TALLOC_ARRAY(mem_ctx, uint32, (n+31)/32);
  76         if (!bm->b) {
  77                 return NULL;
  78         }
  79
  80         memset(bm->b, 0, sizeof(uint32)*((n+31)/32));
  81
  82         return bm;
  83 }
  84
  85 /****************************************************************************
  86 copy as much of the source bitmap as will fit in the destination bitmap.
  87 ****************************************************************************/
  88
  89 int bitmap_copy(struct bitmap * const dst, const struct bitmap * const src)
  90 {
  91         int count = MIN(dst->n, src->n);
  92
  93         SMB_ASSERT(dst->b != src->b);
  94         memcpy(dst->b, src->b, sizeof(uint32)*((count+31)/32));
  95
  96         return count;
  97 }
  98
  99 /****************************************************************************
 100 set a bit in a bitmap
 101 ****************************************************************************/
 102 bool bitmap_set(struct bitmap *bm, unsigned i)
 103 {
 104         if (i >= bm->n) {
 105                 DEBUG(0,("Setting invalid bitmap entry %d (of %d)\n",
 106                       i, bm->n));
 107                 return False;
 108         }
 109         bm->b[i/32] |= (1<<(i%32));
 110         return True;
 111 }
 112
 113 /****************************************************************************
 114 clear a bit in a bitmap
 115 ****************************************************************************/
 116 bool bitmap_clear(struct bitmap *bm, unsigned i)
 117 {
 118         if (i >= bm->n) {
 119                 DEBUG(0,("clearing invalid bitmap entry %d (of %d)\n",
 120                       i, bm->n));
 121                 return False;
 122         }
 123         bm->b[i/32] &= ~(1<<(i%32));
 124         return True;
 125 }
 126
 127 /****************************************************************************
 128 query a bit in a bitmap
 129 ****************************************************************************/
 130 bool bitmap_query(struct bitmap *bm, unsigned i)
 131 {
 132         if (i >= bm->n) return False;
 133         if (bm->b[i/32] & (1<<(i%32))) {
 134                 return True;
 135         }
 136         return False;
 137 }
 138
 139 /****************************************************************************
 140 find a zero bit in a bitmap starting at the specified offset, with
 141 wraparound
 142 ****************************************************************************/
 143 int bitmap_find(struct bitmap *bm, unsigned ofs)
 144 {
 145         unsigned int i, j;
 146
 147         if (ofs > bm->n) ofs = 0;
 148
 149         i = ofs;
 150         while (i < bm->n) {
 151                 if (~(bm->b[i/32])) {
 152                         j = i;
 153                         do {
 154                                 if (!bitmap_query(bm, j)) return j;
 155                                 j++;
 156                         } while (j & 31 && j < bm->n);
 157                 }
 158                 i += 32;
 159                 i &= ~31;
 160         }
 161
 162         i = 0;
 163         while (i < ofs) {
 164                 if (~(bm->b[i/32])) {
 165                         j = i;
 166                         do {
 167                                 if (!bitmap_query(bm, j)) return j;
 168                                 j++;
 169                         } while (j & 31 && j < bm->n);
 170                 }
 171                 i += 32;
 172                 i &= ~31;
 173         }
 174
 175         return -1;
 176 }