src/core/bitmap.c

   1 /*
   2  * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation; either version 2 of the
   7  * License, or any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17  */
  18
  19 #include <errno.h>
  20 #include <gpxe/bitmap.h>
  21
  22 /** @file
  23  *
  24  * Bitmaps for multicast downloads
  25  *
  26  */
  27
  28 /**
  29  * Resize bitmap
  30  *
  31  * @v bitmap            Bitmap
  32  * @v new_length        New length of bitmap, in bits
  33  * @ret rc              Return status code
  34  */
  35 int bitmap_resize ( struct bitmap *bitmap, unsigned int new_length ) {
  36         unsigned int old_num_blocks;
  37         unsigned int new_num_blocks;
  38         size_t new_size;
  39         bitmap_block_t *new_blocks;
  40
  41         old_num_blocks = BITMAP_INDEX ( bitmap->length + BITMAP_BLKSIZE - 1 );
  42         new_num_blocks = BITMAP_INDEX ( new_length + BITMAP_BLKSIZE - 1 );
  43
  44         if ( old_num_blocks != new_num_blocks ) {
  45                 new_size = ( new_num_blocks * sizeof ( bitmap->blocks[0] ) );
  46                 new_blocks = realloc ( bitmap->blocks, new_size );
  47                 if ( ! new_blocks ) {
  48                         DBGC ( bitmap, "Bitmap %p could not resize to %d "
  49                                "bits\n", bitmap, new_length );
  50                         return -ENOMEM;
  51                 }
  52                 bitmap->blocks = new_blocks;
  53         }
  54         bitmap->length = new_length;
  55
  56         while ( old_num_blocks < new_num_blocks ) {
  57                 bitmap->blocks[old_num_blocks++] = 0;
  58         }
  59
  60         DBGC ( bitmap, "Bitmap %p resized to %d bits\n", bitmap, new_length );
  61         return 0;
  62 }
  63
  64 /**
  65  * Test bit in bitmap
  66  *
  67  * @v bitmap            Bitmap
  68  * @v bit               Bit index
  69  * @ret is_set          Bit is set
  70  */
  71 int bitmap_test ( struct bitmap *bitmap, unsigned int bit ) {
  72         unsigned int index = BITMAP_INDEX ( bit );
  73         bitmap_block_t mask = BITMAP_MASK ( bit );
  74
  75         if ( bit >= bitmap->length )
  76                 return 0;
  77         return ( bitmap->blocks[index] & mask );
  78 }
  79
  80 /**
  81  * Set bit in bitmap
  82  *
  83  * @v bitmap            Bitmap
  84  * @v bit               Bit index
  85  */
  86 void bitmap_set ( struct bitmap *bitmap, unsigned int bit ) {
  87         unsigned int index = BITMAP_INDEX ( bit );
  88         bitmap_block_t mask = BITMAP_MASK ( bit );
  89
  90         DBGC ( bitmap, "Bitmap %p setting bit %d\n", bitmap, bit );
  91
  92         /* Update bitmap */
  93         bitmap->blocks[index] |= mask;
  94
  95         /* Update first gap counter */
  96         while ( bitmap_test ( bitmap, bitmap->first_gap ) ) {
  97                 bitmap->first_gap++;
  98         }
  99 }