usr.sbin/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  * $FreeBSD: src/usr.sbin/pw/bitmap.c,v 1.5 1999/08/28 01:19:15 peter Exp $
  27  * $DragonFly: src/usr.sbin/pw/bitmap.c,v 1.2 2003/06/17 04:30:01 dillon Exp $
  28  */
  29
  30 #include <stdlib.h>
  31 #include <string.h>
  32
  33 #include "bitmap.h"
  34
  35 struct bitmap
  36 bm_alloc(int size)
  37 {
  38         struct bitmap   bm;
  39         int             szmap = (size / 8) + !!(size % 8);
  40
  41         bm.size = size;
  42         bm.map = malloc(szmap);
  43         if (bm.map)
  44                 memset(bm.map, 0, szmap);
  45         return bm;
  46 }
  47
  48 void
  49 bm_dealloc(struct bitmap * bm)
  50 {
  51         if (bm->map)
  52                 free(bm->map);
  53 }
  54
  55 static void
  56 bm_getmask(int *pos, unsigned char *bmask)
  57 {
  58         *bmask = (unsigned char) (1 << (*pos % 8));
  59         *pos /= 8;
  60 }
  61
  62 void
  63 bm_setbit(struct bitmap * bm, int pos)
  64 {
  65         unsigned char   bmask;
  66
  67         bm_getmask(&pos, &bmask);
  68         bm->map[pos] |= bmask;
  69 }
  70
  71 void
  72 bm_clrbit(struct bitmap * bm, int pos)
  73 {
  74         unsigned char   bmask;
  75
  76         bm_getmask(&pos, &bmask);
  77         bm->map[pos] &= ~bmask;
  78 }
  79
  80 int
  81 bm_isset(struct bitmap * bm, int pos)
  82 {
  83         unsigned char   bmask;
  84
  85         bm_getmask(&pos, &bmask);
  86         return !!(bm->map[pos] & bmask);
  87 }
  88
  89 int
  90 bm_firstunset(struct bitmap * bm)
  91 {
  92         int             szmap = (bm->size / 8) + !!(bm->size % 8);
  93         int             at = 0;
  94         int             pos = 0;
  95
  96         while (pos < szmap) {
  97                 unsigned char   bmv = bm->map[pos++];
  98                 unsigned char   bmask = 1;
  99
 100                 while (bmask & 0xff) {
 101                         if ((bmv & bmask) == 0)
 102                                 return at;
 103                         bmask <<= 1;
 104                         ++at;
 105                 }
 106         }
 107         return at;
 108 }
 109
 110 int
 111 bm_lastset(struct bitmap * bm)
 112 {
 113         int             szmap = (bm->size / 8) + !!(bm->size % 8);
 114         int             at = 0;
 115         int             pos = 0;
 116         int             ofs = 0;
 117
 118         while (pos < szmap) {
 119                 unsigned char   bmv = bm->map[pos++];
 120                 unsigned char   bmask = 1;
 121
 122                 while (bmask & 0xff) {
 123                         if ((bmv & bmask) != 0)
 124                                 ofs = at;
 125                         bmask <<= 1;
 126                         ++at;
 127                 }
 128         }
 129         return ofs;
 130 }