source/lib/bitmap.c

   1 /*
   2    Unix SMB/Netbios implementation.
   3    Version 1.9.
   4    simple bitmap functions
   5    Copyright (C) Andrew Tridgell 1992-1998
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20 */
  21
  22 #include "includes.h"
  23
  24 extern int DEBUGLEVEL;
  25
  26 /* these functions provide a simple way to allocate integers from a
  27    pool without repitition */
  28
  29
  30 /****************************************************************************
  31 allocate a bitmap of the specified size
  32 ****************************************************************************/
  33 struct bitmap *bitmap_allocate(int n)
  34 {
  35         struct bitmap *bm;
  36
  37         bm = (struct bitmap *)malloc(sizeof(*bm));
  38         bm->n = n;
  39
  40         if (!bm) return NULL;
  41
  42         bm->b = (uint32 *)malloc(sizeof(bm->b[0])*(n+31)/32);
  43         if (!bm->b) {
  44                 free(bm);
  45                 return NULL;
  46         }
  47
  48         memset(bm->b, 0, sizeof(bm->b[0])*(n+31)/32);
  49
  50         return bm;
  51 }
  52
  53 /****************************************************************************
  54 set a bit in a bitmap
  55 ****************************************************************************/
  56 BOOL bitmap_set(struct bitmap *bm, unsigned i)
  57 {
  58         if (i >= bm->n) {
  59                 DEBUG(0,("Setting invalid bitmap entry %d (of %d)\n",
  60                       i, bm->n));
  61                 return False;
  62         }
  63         bm->b[i/32] |= (1<<(i%32));
  64         return True;
  65 }
  66
  67 /****************************************************************************
  68 clear a bit in a bitmap
  69 ****************************************************************************/
  70 BOOL bitmap_clear(struct bitmap *bm, unsigned i)
  71 {
  72         if (i >= bm->n) {
  73                 DEBUG(0,("clearing invalid bitmap entry %d (of %d)\n",
  74                       i, bm->n));
  75                 return False;
  76         }
  77         bm->b[i/32] &= ~(1<<(i%32));
  78         return True;
  79 }
  80
  81 /****************************************************************************
  82 query a bit in a bitmap
  83 ****************************************************************************/
  84 BOOL bitmap_query(struct bitmap *bm, unsigned i)
  85 {
  86         if (i >= bm->n) return False;
  87         if (bm->b[i/32] & (1<<(i%32))) {
  88                 return True;
  89         }
  90         return False;
  91 }
  92
  93 /****************************************************************************
  94 find a zero bit in a bitmap starting at the specified offset, with
  95 wraparound
  96 ****************************************************************************/
  97 int bitmap_find(struct bitmap *bm, unsigned ofs)
  98 {
  99         int i, j;
 100
 101         if (ofs > bm->n) ofs = 0;
 102
 103         i = ofs;
 104         while (i < bm->n) {
 105                 if (~(bm->b[i/32])) {
 106                         j = i;
 107                         do {
 108                                 if (!bitmap_query(bm, j)) return j;
 109                                 j++;
 110                         } while (j & 31 && j < bm->n);
 111                 }
 112                 i += 32;
 113                 i &= ~31;
 114         }
 115
 116         i = 0;
 117         while (i < ofs) {
 118                 if (~(bm->b[i/32])) {
 119                         j = i;
 120                         do {
 121                                 if (!bitmap_query(bm, j)) return j;
 122                                 j++;
 123                         } while (j & 31 && j < bm->n);
 124                 }
 125                 i += 32;
 126                 i &= ~31;
 127         }
 128
 129         return -1;
 130 }