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  *      $Id: bitmap.c,v 1.1.1.1 1996/12/09 14:05:35 joerg Exp $
  27  */
  28
  29 #include <stdlib.h>
  30 #include <string.h>
  31
  32 #include "bitmap.h"
  33
  34 struct bitmap
  35 bm_alloc(int size)
  36 {
  37         struct bitmap   bm;
  38         int             szmap = (size / 8) + !!(size % 8);
  39
  40         bm.size = size;
  41         bm.map = malloc(szmap);
  42         if (bm.map)
  43                 memset(bm.map, 0, szmap);
  44         return bm;
  45 }
  46
  47 void
  48 bm_dealloc(struct bitmap * bm)
  49 {
  50         if (bm->map)
  51                 free(bm->map);
  52 }
  53
  54 static void
  55 bm_getmask(int *pos, unsigned char *bmask)
  56 {
  57         *bmask = (unsigned char) (1 << (*pos % 8));
  58         *pos /= 8;
  59 }
  60
  61 void
  62 bm_setbit(struct bitmap * bm, int pos)
  63 {
  64         unsigned char   bmask;
  65
  66         bm_getmask(&pos, &bmask);
  67         bm->map[pos] |= bmask;
  68 }
  69
  70 void
  71 bm_clrbit(struct bitmap * bm, int pos)
  72 {
  73         unsigned char   bmask;
  74
  75         bm_getmask(&pos, &bmask);
  76         bm->map[pos] &= ~bmask;
  77 }
  78
  79 int
  80 bm_isset(struct bitmap * bm, int pos)
  81 {
  82         unsigned char   bmask;
  83
  84         bm_getmask(&pos, &bmask);
  85         return !!(bm->map[pos] & bmask);
  86 }
  87
  88 int
  89 bm_firstunset(struct bitmap * bm)
  90 {
  91         int             szmap = (bm->size / 8) + !!(bm->size % 8);
  92         int             at = 0;
  93         int             pos = 0;
  94
  95         while (pos < szmap) {
  96                 unsigned char   bmv = bm->map[pos++];
  97                 unsigned char   bmask = 1;
  98
  99                 while (bmask & 0xff) {
 100                         if ((bmv & bmask) == 0)
 101                                 return at;
 102                         bmask <<= 1;
 103                         ++at;
 104                 }
 105         }
 106         return at;
 107 }
 108
 109 int
 110 bm_lastset(struct bitmap * bm)
 111 {
 112         int             szmap = (bm->size / 8) + !!(bm->size % 8);
 113         int             at = 0;
 114         int             pos = 0;
 115         int             ofs = 0;
 116
 117         while (pos < szmap) {
 118                 unsigned char   bmv = bm->map[pos++];
 119                 unsigned char   bmask = 1;
 120
 121                 while (bmask & 0xff) {
 122                         if ((bmv & bmask) != 0)
 123                                 ofs = at;
 124                         bmask <<= 1;
 125                         ++at;
 126                 }
 127         }
 128         return ofs;
 129 }