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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.  
  43. #define ALL_ONES    0xff
  44. #define ALL_ZEROES  0x00
  45.  
  46. /** Initialize bitmap.
  47.  *
  48.  * No portion of the bitmap is set or cleared by this function.
  49.  *
  50.  * @param bitmap Bitmap structure.
  51.  * @param map Address of the memory used to hold the map.
  52.  * @param bits Number of bits stored in bitmap.
  53.  */
  54. void bitmap_initialize(bitmap_t *bitmap, __u8 *map, count_t bits)
  55. {
  56.     bitmap->map = map;
  57.     bitmap->bits = bits;
  58. }
  59.  
  60. /** Set range of bits.
  61.  *
  62.  * @param bitmap Bitmap structure.
  63.  * @param start Starting bit.
  64.  * @param bits Number of bits to set.
  65.  */
  66. void bitmap_set_range(bitmap_t *bitmap, index_t start, count_t bits)
  67. {
  68.     index_t i;
  69.     index_t aligned_start;
  70.     count_t lub;        /* leading unaligned bits */
  71.     count_t tub;        /* trailing unaligned bits */
  72.    
  73.     ASSERT(start + bits <= bitmap->bits);
  74.    
  75.     aligned_start = ALIGN_UP(start, 8);
  76.     lub = aligned_start - start;
  77.     tub = (bits - lub) % 8;
  78.    
  79.     if (lub) {
  80.         /*
  81.          * Make sure to set any leading unaligned bits.
  82.          */
  83.         bitmap->map[start / 8] |= ~((1 << (8 - lub)) - 1);
  84.     }
  85.     for (i = 0; i < (bits - lub) / 8; i++) {
  86.         /*
  87.          * The middle bits can be set byte by byte.
  88.          */
  89.         bitmap->map[aligned_start / 8 + i] = ALL_ONES;
  90.     }
  91.     if (tub) {
  92.         /*
  93.          * Make sure to set any trailing unaligned bits.
  94.          */
  95.         bitmap->map[aligned_start / 8 + i] |= (1 << tub) - 1;
  96.     }
  97.    
  98. }
  99.  
  100. /** Clear range of bits.
  101.  *
  102.  * @param bitmap Bitmap structure.
  103.  * @param start Starting bit.
  104.  * @param bits Number of bits to clear.
  105.  */
  106. void bitmap_clear_range(bitmap_t *bitmap, index_t start, count_t bits)
  107. {
  108.     index_t i;
  109.     index_t aligned_start;
  110.     count_t lub;        /* leading unaligned bits */
  111.     count_t tub;        /* trailing unaligned bits */
  112.    
  113.     ASSERT(start + bits <= bitmap->bits);
  114.    
  115.     aligned_start = ALIGN_UP(start, 8);
  116.     lub = aligned_start - start;
  117.     tub = (bits - lub) % 8;
  118.    
  119.     if (lub) {
  120.         /*
  121.          * Make sure to clear any leading unaligned bits.
  122.          */
  123.         bitmap->map[start / 8] &= (1 << (8 - lub)) - 1;
  124.     }
  125.     for (i = 0; i < (bits - lub) / 8; i++) {
  126.         /*
  127.          * The middle bits can be cleared byte by byte.
  128.          */
  129.         bitmap->map[aligned_start / 8 + i] = ALL_ZEROES;
  130.     }
  131.     if (tub) {
  132.         /*
  133.          * Make sure to clear any trailing unaligned bits.
  134.          */
  135.         bitmap->map[aligned_start / 8 + i] &= ~((1 << tub) - 1);
  136.     }
  137.    
  138. }
  139.  
  140. /** Copy portion of one bitmap into another bitmap.
  141.  *
  142.  * @param dst Destination bitmap.
  143.  * @param src Source bitmap.
  144.  * @param bits Number of bits to copy.
  145.  */
  146. void bitmap_copy(bitmap_t *dst, bitmap_t *src, count_t bits)
  147. {
  148.     index_t i;
  149.    
  150.     ASSERT(bits <= dst->bits);
  151.     ASSERT(bits <= src->bits);
  152.    
  153.     for (i = 0; i < bits / 8; i++)
  154.         dst->map[i] = src->map[i];
  155.    
  156.     if (bits % 8) {
  157.         bitmap_clear_range(dst, i * 8, bits % 8);
  158.         dst->map[i] |= src->map[i] & ((1 << (bits % 8)) - 1);
  159.     }
  160. }
  161.