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  1. /*
  2.  * Copyright (C) 2006 Jakub Jermar
  3.  * 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.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. /**
  30.  * @file    bitmap.c
  31.  * @brief   Implementation of bitmap ADT.
  32.  *
  33.  * This file implements bitmap ADT and provides functions for
  34.  * setting and clearing ranges of bits.
  35.  */
  36.  
  37. #include <adt/bitmap.h>
  38. #include <typedefs.h>
  39. #include <arch/types.h>
  40. #include <align.h>
  41. #include <debug.h>
  42. #include <macros.h>
  43.  
  44. #define ALL_ONES    0xff
  45. #define ALL_ZEROES  0x00
  46.  
  47. /** Initialize bitmap.
  48.  *
  49.  * No portion of the bitmap is set or cleared by this function.
  50.  *
  51.  * @param bitmap Bitmap structure.
  52.  * @param map Address of the memory used to hold the map.
  53.  * @param bits Number of bits stored in bitmap.
  54.  */
  55. void bitmap_initialize(bitmap_t *bitmap, __u8 *map, count_t bits)
  56. {
  57.     bitmap->map = map;
  58.     bitmap->bits = bits;
  59. }
  60.  
  61. /** Set range of bits.
  62.  *
  63.  * @param bitmap Bitmap structure.
  64.  * @param start Starting bit.
  65.  * @param bits Number of bits to set.
  66.  */
  67. void bitmap_set_range(bitmap_t *bitmap, index_t start, count_t bits)
  68. {
  69.     index_t i;
  70.     index_t aligned_start;
  71.     count_t lub;        /* leading unaligned bits */
  72.     count_t amb;        /* aligned middle bits */
  73.     count_t tab;        /* trailing aligned bits */
  74.    
  75.     ASSERT(start + bits <= bitmap->bits);
  76.    
  77.     aligned_start = ALIGN_UP(start, 8);
  78.     lub = min(aligned_start - start, bits);
  79.     amb = bits > lub ? bits - lub : 0;
  80.     tab = amb % 8;
  81.    
  82.     if (lub) {
  83.         /*
  84.          * Make sure to set any leading unaligned bits.
  85.          */
  86.         bitmap->map[start / 8] |= ~((1 << (8 - lub)) - 1);
  87.     }
  88.     for (i = 0; i < amb / 8; i++) {
  89.         /*
  90.          * The middle bits can be set byte by byte.
  91.          */
  92.         bitmap->map[aligned_start / 8 + i] = ALL_ONES;
  93.     }
  94.     if (tab) {
  95.         /*
  96.          * Make sure to set any trailing aligned bits.
  97.          */
  98.         bitmap->map[aligned_start / 8 + i] |= (1 << tab) - 1;
  99.     }
  100.    
  101. }
  102.  
  103. /** Clear range of bits.
  104.  *
  105.  * @param bitmap Bitmap structure.
  106.  * @param start Starting bit.
  107.  * @param bits Number of bits to clear.
  108.  */
  109. void bitmap_clear_range(bitmap_t *bitmap, index_t start, count_t bits)
  110. {
  111.     index_t i;
  112.     index_t aligned_start;
  113.     count_t lub;        /* leading unaligned bits */
  114.     count_t amb;        /* aligned middle bits */
  115.     count_t tab;        /* trailing aligned bits */
  116.    
  117.     ASSERT(start + bits <= bitmap->bits);
  118.    
  119.     aligned_start = ALIGN_UP(start, 8);
  120.     lub = min(aligned_start - start, bits);
  121.     amb = bits > lub ? bits - lub : 0;
  122.     tab = amb % 8;
  123.  
  124.     if (lub) {
  125.         /*
  126.          * Make sure to clear any leading unaligned bits.
  127.          */
  128.         bitmap->map[start / 8] &= (1 << (8 - lub)) - 1;
  129.     }
  130.     for (i = 0; i < amb / 8; i++) {
  131.         /*
  132.          * The middle bits can be cleared byte by byte.
  133.          */
  134.         bitmap->map[aligned_start / 8 + i] = ALL_ZEROES;
  135.     }
  136.     if (tab) {
  137.         /*
  138.          * Make sure to clear any trailing aligned bits.
  139.          */
  140.         bitmap->map[aligned_start / 8 + i] &= ~((1 << tab) - 1);
  141.     }
  142.  
  143. }
  144.  
  145. /** Copy portion of one bitmap into another bitmap.
  146.  *
  147.  * @param dst Destination bitmap.
  148.  * @param src Source bitmap.
  149.  * @param bits Number of bits to copy.
  150.  */
  151. void bitmap_copy(bitmap_t *dst, bitmap_t *src, count_t bits)
  152. {
  153.     index_t i;
  154.    
  155.     ASSERT(bits <= dst->bits);
  156.     ASSERT(bits <= src->bits);
  157.    
  158.     for (i = 0; i < bits / 8; i++)
  159.         dst->map[i] = src->map[i];
  160.    
  161.     if (bits % 8) {
  162.         bitmap_clear_range(dst, i * 8, bits % 8);
  163.         dst->map[i] |= src->map[i] & ((1 << (bits % 8)) - 1);
  164.     }
  165. }
  166.