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
  39         if (!bm) return NULL;
  40
  41         bm->n = n;
  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 free a bitmap.
  55 ****************************************************************************/
  56
  57 void bitmap_free(struct bitmap *bm)
  58 {
  59         if (!bm)
  60                 return;
  61
  62         if(bm->b)
  63                 free(bm->b);
  64
  65         free(bm);
  66 }
  67
  68 /****************************************************************************
  69 set a bit in a bitmap
  70 ****************************************************************************/
  71 BOOL bitmap_set(struct bitmap *bm, unsigned i)
  72 {
  73         if (i >= bm->n) {
  74                 DEBUG(0,("Setting invalid bitmap entry %d (of %d)\n",
  75                       i, bm->n));
  76                 return False;
  77         }
  78         bm->b[i/32] |= (1<<(i%32));
  79         return True;
  80 }
  81
  82 /****************************************************************************
  83 clear a bit in a bitmap
  84 ****************************************************************************/
  85 BOOL bitmap_clear(struct bitmap *bm, unsigned i)
  86 {
  87         if (i >= bm->n) {
  88                 DEBUG(0,("clearing invalid bitmap entry %d (of %d)\n",
  89                       i, bm->n));
  90                 return False;
  91         }
  92         bm->b[i/32] &= ~(1<<(i%32));
  93         return True;
  94 }
  95
  96 /****************************************************************************
  97 query a bit in a bitmap
  98 ****************************************************************************/
  99 BOOL bitmap_query(struct bitmap *bm, unsigned i)
 100 {
 101         if (i >= bm->n) return False;
 102         if (bm->b[i/32] & (1<<(i%32))) {
 103                 return True;
 104         }
 105         return False;
 106 }
 107
 108 /****************************************************************************
 109 find a zero bit in a bitmap starting at the specified offset, with
 110 wraparound
 111 ****************************************************************************/
 112 int bitmap_find(struct bitmap *bm, unsigned ofs)
 113 {
 114         int i, j;
 115
 116         if (ofs > bm->n) ofs = 0;
 117
 118         i = ofs;
 119         while (i < bm->n) {
 120                 if (~(bm->b[i/32])) {
 121                         j = i;
 122                         do {
 123                                 if (!bitmap_query(bm, j)) return j;
 124                                 j++;
 125                         } while (j & 31 && j < bm->n);
 126                 }
 127                 i += 32;
 128                 i &= ~31;
 129         }
 130
 131         i = 0;
 132         while (i < ofs) {
 133                 if (~(bm->b[i/32])) {
 134                         j = i;
 135                         do {
 136                                 if (!bitmap_query(bm, j)) return j;
 137                                 j++;
 138                         } while (j & 31 && j < bm->n);
 139                 }
 140                 i += 32;
 141                 i &= ~31;
 142         }
 143
 144         return -1;
 145 }