release/src/router/samba3/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 2 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, write to the Free Software
  18    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19 */
  20
  21 #include "includes.h"
  22
  23 /* these functions provide a simple way to allocate integers from a
  24    pool without repetition */
  25
  26 /****************************************************************************
  27 allocate a bitmap of the specified size
  28 ****************************************************************************/
  29 struct bitmap *bitmap_allocate(int n)
  30 {
  31         struct bitmap *bm;
  32
  33         bm = SMB_MALLOC_P(struct bitmap);
  34
  35         if (!bm) return NULL;
  36
  37         bm->n = n;
  38         bm->b = SMB_MALLOC_ARRAY(uint32, (n+31)/32);
  39         if (!bm->b) {
  40                 SAFE_FREE(bm);
  41                 return NULL;
  42         }
  43
  44         memset(bm->b, 0, sizeof(uint32)*((n+31)/32));
  45
  46         return bm;
  47 }
  48
  49 /****************************************************************************
  50 free a bitmap.
  51 ****************************************************************************/
  52
  53 void bitmap_free(struct bitmap *bm)
  54 {
  55         if (!bm)
  56                 return;
  57
  58         SAFE_FREE(bm->b);
  59         SAFE_FREE(bm);
  60 }
  61
  62 /****************************************************************************
  63 talloc a bitmap
  64 ****************************************************************************/
  65 struct bitmap *bitmap_talloc(TALLOC_CTX *mem_ctx, int n)
  66 {
  67         struct bitmap *bm;
  68
  69         if (!mem_ctx) return NULL;
  70
  71         bm = TALLOC_P(mem_ctx, struct bitmap);
  72
  73         if (!bm) return NULL;
  74
  75         bm->n = n;
  76         bm->b = TALLOC_ARRAY(mem_ctx, uint32, (n+31)/32);
  77         if (!bm->b) {
  78                 return NULL;
  79         }
  80
  81         memset(bm->b, 0, sizeof(uint32)*((n+31)/32));
  82
  83         return bm;
  84 }
  85
  86 /****************************************************************************
  87 copy as much of the source bitmap as will fit in the destination bitmap.
  88 ****************************************************************************/
  89
  90 int bitmap_copy(struct bitmap * const dst, const struct bitmap * const src)
  91 {
  92         int count = MIN(dst->n, src->n);
  93
  94         SMB_ASSERT(dst->b != src->b);
  95         memcpy(dst->b, src->b, sizeof(uint32)*((count+31)/32));
  96
  97         return count;
  98 }
  99
 100 /****************************************************************************
 101 set a bit in a bitmap
 102 ****************************************************************************/
 103 BOOL bitmap_set(struct bitmap *bm, unsigned i)
 104 {
 105         if (i >= bm->n) {
 106                 DEBUG(0,("Setting invalid bitmap entry %d (of %d)\n",
 107                       i, bm->n));
 108                 return False;
 109         }
 110         bm->b[i/32] |= (1<<(i%32));
 111         return True;
 112 }
 113
 114 /****************************************************************************
 115 clear a bit in a bitmap
 116 ****************************************************************************/
 117 BOOL bitmap_clear(struct bitmap *bm, unsigned i)
 118 {
 119         if (i >= bm->n) {
 120                 DEBUG(0,("clearing invalid bitmap entry %d (of %d)\n",
 121                       i, bm->n));
 122                 return False;
 123         }
 124         bm->b[i/32] &= ~(1<<(i%32));
 125         return True;
 126 }
 127
 128 /****************************************************************************
 129 query a bit in a bitmap
 130 ****************************************************************************/
 131 BOOL bitmap_query(struct bitmap *bm, unsigned i)
 132 {
 133         if (i >= bm->n) return False;
 134         if (bm->b[i/32] & (1<<(i%32))) {
 135                 return True;
 136         }
 137         return False;
 138 }
 139
 140 /****************************************************************************
 141 find a zero bit in a bitmap starting at the specified offset, with
 142 wraparound
 143 ****************************************************************************/
 144 int bitmap_find(struct bitmap *bm, unsigned ofs)
 145 {
 146         unsigned int i, j;
 147
 148         if (ofs > bm->n) ofs = 0;
 149
 150         i = ofs;
 151         while (i < bm->n) {
 152                 if (~(bm->b[i/32])) {
 153                         j = i;
 154                         do {
 155                                 if (!bitmap_query(bm, j)) return j;
 156                                 j++;
 157                         } while (j & 31 && j < bm->n);
 158                 }
 159                 i += 32;
 160                 i &= ~31;
 161         }
 162
 163         i = 0;
 164         while (i < ofs) {
 165                 if (~(bm->b[i/32])) {
 166                         j = i;
 167                         do {
 168                                 if (!bitmap_query(bm, j)) return j;
 169                                 j++;
 170                         } while (j & 31 && j < bm->n);
 171                 }
 172                 i += 32;
 173                 i &= ~31;
 174         }
 175
 176         return -1;
 177 }