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1200 jermar 1 
/*
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 * Copyright (c) 2006 Jakub Jermar
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 *
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 * - Redistributions of source code must retain the above copyright
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 *   notice, this list of conditions and the following disclaimer.
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 * - Redistributions in binary form must reproduce the above copyright
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 *   notice, this list of conditions and the following disclaimer in the
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 *   documentation and/or other materials provided with the distribution.
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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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/** @addtogroup genericadt
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 * @{
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 */
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/**
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 * @file
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 * @brief   Implementation of bitmap ADT.
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 *
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 * This file implements bitmap ADT and provides functions for
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 * setting and clearing ranges of bits.
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 */
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#include <adt/bitmap.h>
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#include <arch/types.h>
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#include <align.h>
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#include <debug.h>
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#include <macros.h>
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#define ALL_ONES    0xff
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#define ALL_ZEROES  0x00
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/** Initialize bitmap.
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 *
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 * No portion of the bitmap is set or cleared by this function.
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 *
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 * @param bitmap Bitmap structure.
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 * @param map Address of the memory used to hold the map.
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 * @param bits Number of bits stored in bitmap.
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 */
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void bitmap_initialize(bitmap_t *bitmap, uint8_t *map, size_t bits)
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{
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    bitmap->map = map;
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    bitmap->bits = bits;
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}
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/** Set range of bits.
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 *
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 * @param bitmap Bitmap structure.
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 * @param start Starting bit.
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 * @param bits Number of bits to set.
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 */
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void bitmap_set_range(bitmap_t *bitmap, size_t start, size_t bits)
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{
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    size_t i = 0;
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    size_t aligned_start;
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    size_t lub;     /* leading unaligned bits */
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    size_t amb;     /* aligned middle bits */
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    size_t tab;     /* trailing aligned bits */
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    ASSERT(start + bits <= bitmap->bits);
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    aligned_start = ALIGN_UP(start, 8);
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    lub = min(aligned_start - start, bits);
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    amb = bits > lub ? bits - lub : 0;
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    tab = amb % 8;
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    if ( start + bits < aligned_start ) {
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        /*
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        * Set bits in the middle of byte
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        */
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        bitmap->map[start / 8] |= ((1 << lub)-1) << (start&7);
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        return;
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    }
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    if (lub) {
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        /*
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         * Make sure to set any leading unaligned bits.
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         */
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        bitmap->map[start / 8] |= ~((1 << (8 - lub)) - 1);
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    }
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    for (i = 0; i < amb / 8; i++) {
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        /*
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         * The middle bits can be set byte by byte.
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         */
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        bitmap->map[aligned_start / 8 + i] = ALL_ONES;
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    }
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    if (tab) {
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        /*
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         * Make sure to set any trailing aligned bits.
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         */
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        bitmap->map[aligned_start / 8 + i] |= (1 << tab) - 1;
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    }
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}
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/** Clear range of bits.
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 *
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 * @param bitmap Bitmap structure.
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 * @param start Starting bit.
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 * @param bits Number of bits to clear.
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 */
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void bitmap_clear_range(bitmap_t *bitmap, size_t start, size_t bits)
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{
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    size_t i = 0;
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    size_t aligned_start;
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    size_t lub;     /* leading unaligned bits */
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    size_t amb;     /* aligned middle bits */
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    size_t tab;     /* trailing aligned bits */
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    ASSERT(start + bits <= bitmap->bits);
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    aligned_start = ALIGN_UP(start, 8);
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    lub = min(aligned_start - start, bits);
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    amb = bits > lub ? bits - lub : 0;
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    tab = amb % 8;
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    if ( start + bits < aligned_start )
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    {
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        /*
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        * Set bits in the middle of byte
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        */
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        bitmap->map[start / 8] &= ~(((1 << lub)-1) << (start&7));
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        return;
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    }
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    if (lub) {
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        /*
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         * Make sure to clear any leading unaligned bits.
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         */
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        bitmap->map[start / 8] &= (1 << (8 - lub)) - 1;
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    }
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    for (i = 0; i < amb / 8; i++) {
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        /*
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         * The middle bits can be cleared byte by byte.
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         */
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        bitmap->map[aligned_start / 8 + i] = ALL_ZEROES;
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    }
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    if (tab) {
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        /*
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         * Make sure to clear any trailing aligned bits.
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         */
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        bitmap->map[aligned_start / 8 + i] &= ~((1 << tab) - 1);
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    }
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}
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/** Copy portion of one bitmap into another bitmap.
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 *
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 * @param dst Destination bitmap.
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 * @param src Source bitmap.
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 * @param bits Number of bits to copy.
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 */
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void bitmap_copy(bitmap_t *dst, bitmap_t *src, size_t bits)
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{
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    size_t i;
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    ASSERT(bits <= dst->bits);
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    ASSERT(bits <= src->bits);
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    for (i = 0; i < bits / 8; i++)
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        dst->map[i] = src->map[i];
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    if (bits % 8) {
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        bitmap_clear_range(dst, i * 8, bits % 8);
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        dst->map[i] |= src->map[i] & ((1 << (bits % 8)) - 1);
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    }
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}
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/** @}
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 */