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 FILE_LICENCE ( GPL2_OR_LATER );
  20
  21 #include <errno.h>
  22 #include <gpxe/bitmap.h>
  23
  24 /** @file
  25  *
  26  * Bitmaps for multicast downloads
  27  *
  28  */
  29
  30 /**
  31  * Resize bitmap
  32  *
  33  * @v bitmap            Bitmap
  34  * @v new_length        New length of bitmap, in bits
  35  * @ret rc              Return status code
  36  */
  37 int bitmap_resize ( struct bitmap *bitmap, unsigned int new_length ) {
  38         unsigned int old_num_blocks;
  39         unsigned int new_num_blocks;
  40         size_t new_size;
  41         bitmap_block_t *new_blocks;
  42
  43         old_num_blocks = BITMAP_INDEX ( bitmap->length + BITMAP_BLKSIZE - 1 );
  44         new_num_blocks = BITMAP_INDEX ( new_length + BITMAP_BLKSIZE - 1 );
  45
  46         if ( old_num_blocks != new_num_blocks ) {
  47                 new_size = ( new_num_blocks * sizeof ( bitmap->blocks[0] ) );
  48                 new_blocks = realloc ( bitmap->blocks, new_size );
  49                 if ( ! new_blocks ) {
  50                         DBGC ( bitmap, "Bitmap %p could not resize to %d "
  51                                "bits\n", bitmap, new_length );
  52                         return -ENOMEM;
  53                 }
  54                 bitmap->blocks = new_blocks;
  55         }
  56         bitmap->length = new_length;
  57
  58         while ( old_num_blocks < new_num_blocks ) {
  59                 bitmap->blocks[old_num_blocks++] = 0;
  60         }
  61
  62         DBGC ( bitmap, "Bitmap %p resized to %d bits\n", bitmap, new_length );
  63         return 0;
  64 }
  65
  66 /**
  67  * Test bit in bitmap
  68  *
  69  * @v bitmap            Bitmap
  70  * @v bit               Bit index
  71  * @ret is_set          Bit is set
  72  */
  73 int bitmap_test ( struct bitmap *bitmap, unsigned int bit ) {
  74         unsigned int index = BITMAP_INDEX ( bit );
  75         bitmap_block_t mask = BITMAP_MASK ( bit );
  76
  77         if ( bit >= bitmap->length )
  78                 return 0;
  79         return ( bitmap->blocks[index] & mask ) != 0;
  80 }
  81
  82 /**
  83  * Set bit in bitmap
  84  *
  85  * @v bitmap            Bitmap
  86  * @v bit               Bit index
  87  */
  88 void bitmap_set ( struct bitmap *bitmap, unsigned int bit ) {
  89         unsigned int index = BITMAP_INDEX ( bit );
  90         bitmap_block_t mask = BITMAP_MASK ( bit );
  91
  92         DBGC ( bitmap, "Bitmap %p setting bit %d\n", bitmap, bit );
  93
  94         /* Update bitmap */
  95         bitmap->blocks[index] |= mask;
  96
  97         /* Update first gap counter */
  98         while ( bitmap_test ( bitmap, bitmap->first_gap ) ) {
  99                 bitmap->first_gap++;
 100         }
 101 }