bitmap.c

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/*
 * Copyright (C) 2006 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <adt/bitmap.h>
#include <typedefs.h>
#include <arch/types.h>
#include <align.h>
#include <debug.h>
#include <macros.h>

#define ALL_ONES        0xff
#define ALL_ZEROES      0x00

void bitmap_initialize(bitmap_t *bitmap, __u8 *map, count_t bits)
{
        bitmap->map = map;
        bitmap->bits = bits;
}

void bitmap_set_range(bitmap_t *bitmap, index_t start, count_t bits)
{
        index_t i=0;
        index_t aligned_start;
        count_t lub;            /* leading unaligned bits */
        count_t amb;            /* aligned middle bits */
        count_t tab;            /* trailing aligned bits */
        
        ASSERT(start + bits <= bitmap->bits);
        
        aligned_start = ALIGN_UP(start, 8);
        lub = min(aligned_start - start, bits);
        amb = bits > lub ? bits - lub : 0;
        tab = amb % 8;
        
        if ( start + bits < aligned_start ) {
            /*
            * Set bits in the middle of byte
            */
            bitmap->map[start / 8] |= ((1 << lub)-1) << (start&7);
            return;
        }
        
        if (lub) {
                /*
                 * Make sure to set any leading unaligned bits.
                 */
                bitmap->map[start / 8] |= ~((1 << (8 - lub)) - 1);
        }
        for (i = 0; i < amb / 8; i++) {
                /*
                 * The middle bits can be set byte by byte.
                 */
                bitmap->map[aligned_start / 8 + i] = ALL_ONES;
        }
        if (tab) {
                /*
                 * Make sure to set any trailing aligned bits.
                 */
                bitmap->map[aligned_start / 8 + i] |= (1 << tab) - 1;
        }
        
}

void bitmap_clear_range(bitmap_t *bitmap, index_t start, count_t bits)
{
        index_t i=0;
        index_t aligned_start;
        count_t lub;            /* leading unaligned bits */
        count_t amb;            /* aligned middle bits */
        count_t tab;            /* trailing aligned bits */
        
        ASSERT(start + bits <= bitmap->bits);
        
        aligned_start = ALIGN_UP(start, 8);
        lub = min(aligned_start - start, bits);
        amb = bits > lub ? bits - lub : 0;
        tab = amb % 8;

        if ( start + bits < aligned_start )
        {
            /*
            * Set bits in the middle of byte
            */
            bitmap->map[start / 8] &= ~(((1 << lub)-1) << (start&7));
            return;
        }


        if (lub) {
                /*
                 * Make sure to clear any leading unaligned bits.
                 */
                bitmap->map[start / 8] &= (1 << (8 - lub)) - 1;
        }
        for (i = 0; i < amb / 8; i++) {
                /*
                 * The middle bits can be cleared byte by byte.
                 */
                bitmap->map[aligned_start / 8 + i] = ALL_ZEROES;
        }
        if (tab) {
                /*
                 * Make sure to clear any trailing aligned bits.
                 */
                bitmap->map[aligned_start / 8 + i] &= ~((1 << tab) - 1);
        }

}

void bitmap_copy(bitmap_t *dst, bitmap_t *src, count_t bits)
{
        index_t i;
        
        ASSERT(bits <= dst->bits);
        ASSERT(bits <= src->bits);
        
        for (i = 0; i < bits / 8; i++)
                dst->map[i] = src->map[i];
        
        if (bits % 8) {
                bitmap_clear_range(dst, i * 8, bits % 8);
                dst->map[i] |= src->map[i] & ((1 << (bits % 8)) - 1);
        }
}

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