pw/bitmap.c

   1 /*-
   2  * Copyright (C) 1996
   3  *      David L. Nugent.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY DAVID L. NUGENT AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL DAVID L. NUGENT OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  */
  26
  27 #ifndef lint
  28 static const char rcsid[] =
  29   "$FreeBSD$";
  30 #endif /* not lint */
  31
  32 #include <stdlib.h>
  33 #include <string.h>
  34
  35 #include "bitmap.h"
  36
  37 struct bitmap
  38 bm_alloc(int size)
  39 {
  40         struct bitmap   bm;
  41         int             szmap = (size / 8) + !!(size % 8);
  42
  43         bm.size = size;
  44         bm.map = malloc(szmap);
  45         if (bm.map)
  46                 memset(bm.map, 0, szmap);
  47         return bm;
  48 }
  49
  50 void
  51 bm_dealloc(struct bitmap * bm)
  52 {
  53         if (bm->map)
  54                 free(bm->map);
  55 }
  56
  57 static void
  58 bm_getmask(int *pos, unsigned char *bmask)
  59 {
  60         *bmask = (unsigned char) (1 << (*pos % 8));
  61         *pos /= 8;
  62 }
  63
  64 void
  65 bm_setbit(struct bitmap * bm, int pos)
  66 {
  67         unsigned char   bmask;
  68
  69         bm_getmask(&pos, &bmask);
  70         bm->map[pos] |= bmask;
  71 }
  72
  73 void
  74 bm_clrbit(struct bitmap * bm, int pos)
  75 {
  76         unsigned char   bmask;
  77
  78         bm_getmask(&pos, &bmask);
  79         bm->map[pos] &= ~bmask;
  80 }
  81
  82 int
  83 bm_isset(struct bitmap * bm, int pos)
  84 {
  85         unsigned char   bmask;
  86
  87         bm_getmask(&pos, &bmask);
  88         return !!(bm->map[pos] & bmask);
  89 }
  90
  91 int
  92 bm_firstunset(struct bitmap * bm)
  93 {
  94         int             szmap = (bm->size / 8) + !!(bm->size % 8);
  95         int             at = 0;
  96         int             pos = 0;
  97
  98         while (pos < szmap) {
  99                 unsigned char   bmv = bm->map[pos++];
 100                 unsigned char   bmask = 1;
 101
 102                 while (bmask & 0xff) {
 103                         if ((bmv & bmask) == 0)
 104                                 return at;
 105                         bmask <<= 1;
 106                         ++at;
 107                 }
 108         }
 109         return at;
 110 }
 111
 112 int
 113 bm_lastset(struct bitmap * bm)
 114 {
 115         int             szmap = (bm->size / 8) + !!(bm->size % 8);
 116         int             at = 0;
 117         int             pos = 0;
 118         int             ofs = 0;
 119
 120         while (pos < szmap) {
 121                 unsigned char   bmv = bm->map[pos++];
 122                 unsigned char   bmask = 1;
 123
 124                 while (bmask & 0xff) {
 125                         if ((bmv & bmask) != 0)
 126                                 ofs = at;
 127                         bmask <<= 1;
 128                         ++at;
 129                 }
 130         }
 131         return ofs;
 132 }