source3/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 = (struct bitmap *)malloc(sizeof(*bm));
  34
  35         if (!bm) return NULL;
  36
  37         bm->n = n;
  38         bm->b = (uint32 *)malloc(sizeof(bm->b[0])*(n+31)/32);
  39         if (!bm->b) {
  40                 SAFE_FREE(bm);
  41                 return NULL;
  42         }
  43
  44         memset(bm->b, 0, sizeof(bm->b[0])*(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 = (struct bitmap *)talloc(mem_ctx, sizeof(*bm));
  72
  73         if (!bm) return NULL;
  74
  75         bm->n = n;
  76         bm->b = (uint32 *)talloc(mem_ctx, sizeof(bm->b[0])*(n+31)/32);
  77         if (!bm->b) {
  78                 return NULL;
  79         }
  80
  81         memset(bm->b, 0, sizeof(bm->b[0])*(n+31)/32);
  82
  83         return bm;
  84 }
  85
  86 /****************************************************************************
  87 set a bit in a bitmap
  88 ****************************************************************************/
  89 BOOL bitmap_set(struct bitmap *bm, unsigned i)
  90 {
  91         if (i >= bm->n) {
  92                 DEBUG(0,("Setting invalid bitmap entry %d (of %d)\n",
  93                       i, bm->n));
  94                 return False;
  95         }
  96         bm->b[i/32] |= (1<<(i%32));
  97         return True;
  98 }
  99
 100 /****************************************************************************
 101 clear a bit in a bitmap
 102 ****************************************************************************/
 103 BOOL bitmap_clear(struct bitmap *bm, unsigned i)
 104 {
 105         if (i >= bm->n) {
 106                 DEBUG(0,("clearing 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 query a bit in a bitmap
 116 ****************************************************************************/
 117 BOOL bitmap_query(struct bitmap *bm, unsigned i)
 118 {
 119         if (i >= bm->n) return False;
 120         if (bm->b[i/32] & (1<<(i%32))) {
 121                 return True;
 122         }
 123         return False;
 124 }
 125
 126 /****************************************************************************
 127 find a zero bit in a bitmap starting at the specified offset, with
 128 wraparound
 129 ****************************************************************************/
 130 int bitmap_find(struct bitmap *bm, unsigned ofs)
 131 {
 132         unsigned int i, j;
 133
 134         if (ofs > bm->n) ofs = 0;
 135
 136         i = ofs;
 137         while (i < bm->n) {
 138                 if (~(bm->b[i/32])) {
 139                         j = i;
 140                         do {
 141                                 if (!bitmap_query(bm, j)) return j;
 142                                 j++;
 143                         } while (j & 31 && j < bm->n);
 144                 }
 145                 i += 32;
 146                 i &= ~31;
 147         }
 148
 149         i = 0;
 150         while (i < ofs) {
 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         return -1;
 163 }