src/daemon/bitmap.c

   1 /* -*- mode: c; c-file-style: "openbsd" -*- */
   2 /*
   3  * Copyright (c) 2020 Vincent Bernat <bernat@luffy.cx>
   4  *
   5  * Permission to use, copy, modify, and/or distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 /* Helpers around bitmaps */
  19
  20 #include "lldpd.h"
  21
  22 /*
  23  * Set vlan id in the bitmap
  24  */
  25 void
  26 bitmap_set(uint32_t *bmap, uint16_t vlan_id)
  27 {
  28         if (vlan_id < MAX_VLAN)
  29                 bmap[vlan_id / 32] |= (((uint32_t) 1) << (vlan_id % 32));
  30 }
  31
  32 /*
  33  * Checks if the bitmap is empty
  34  */
  35 int
  36 bitmap_isempty(uint32_t *bmap)
  37 {
  38         int i;
  39
  40         for (i = 0; i < VLAN_BITMAP_LEN; i++) {
  41                 if (bmap[i] != 0)
  42                         return 0;
  43         }
  44
  45         return 1;
  46 }
  47
  48 /*
  49  * Calculate the number of bits set in the bitmap to get total
  50  * number of VLANs
  51  */
  52 unsigned int
  53 bitmap_numbits(uint32_t *bmap)
  54 {
  55         unsigned int num = 0;
  56
  57         for (int i = 0; (i < VLAN_BITMAP_LEN); i++) {
  58                 uint32_t v = bmap[i];
  59                 v = v - ((v >> 1) & 0x55555555);
  60                 v = (v & 0x33333333) + ((v >> 2) & 0x33333333);
  61                 num += (((v + (v >> 4)) & 0x0F0F0F0F) * 0x01010101) >> 24;
  62         }
  63
  64         return num;
  65 }