Archipelago » qemu

/*

 * Bitmap Module

 *

 * Stolen from linux/src/lib/bitmap.c

 *

 * Copyright (C) 2010 Corentin Chary

 *

 * This source code is licensed under the GNU General Public License,

 * Version 2.

 */

#include "qemu/bitops.h"

#include "qemu/bitmap.h"

/*

 * bitmaps provide an array of bits, implemented using an an

 * array of unsigned longs.  The number of valid bits in a

 * given bitmap does _not_ need to be an exact multiple of

 * BITS_PER_LONG.

 *

 * The possible unused bits in the last, partially used word

 * of a bitmap are 'don't care'.  The implementation makes

 * no particular effort to keep them zero.  It ensures that

 * their value will not affect the results of any operation.

 * The bitmap operations that return Boolean (bitmap_empty,

 * for example) or scalar (bitmap_weight, for example) results

 * carefully filter out these unused bits from impacting their

 * results.

 *

 * These operations actually hold to a slightly stronger rule:

 * if you don't input any bitmaps to these ops that have some

 * unused bits set, then they won't output any set unused bits

 * in output bitmaps.

 *

 * The byte ordering of bitmaps is more natural on little

 * endian architectures.

 */

int slow_bitmap_empty(const unsigned long *bitmap, int bits)

{

    int k, lim = bits/BITS_PER_LONG;

    for (k = 0; k < lim; ++k) {

        if (bitmap[k]) {

            return 0;

        }

    }

    if (bits % BITS_PER_LONG) {

        if (bitmap[k] & BITMAP_LAST_WORD_MASK(bits)) {

            return 0;

        }

    }

    return 1;

}

int slow_bitmap_full(const unsigned long *bitmap, int bits)

{

    int k, lim = bits/BITS_PER_LONG;

    for (k = 0; k < lim; ++k) {

        if (~bitmap[k]) {

            return 0;

        }

    }

    if (bits % BITS_PER_LONG) {

        if (~bitmap[k] & BITMAP_LAST_WORD_MASK(bits)) {

            return 0;

        }

    }

    return 1;

}

int slow_bitmap_equal(const unsigned long *bitmap1,

                      const unsigned long *bitmap2, int bits)

{

    int k, lim = bits/BITS_PER_LONG;

    for (k = 0; k < lim; ++k) {

        if (bitmap1[k] != bitmap2[k]) {

            return 0;

        }

    }

    if (bits % BITS_PER_LONG) {

        if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits)) {

            return 0;

        }

    }

    return 1;

}

void slow_bitmap_complement(unsigned long *dst, const unsigned long *src,

                            int bits)

{

    int k, lim = bits/BITS_PER_LONG;

    for (k = 0; k < lim; ++k) {

        dst[k] = ~src[k];

    }

    if (bits % BITS_PER_LONG) {

        dst[k] = ~src[k] & BITMAP_LAST_WORD_MASK(bits);

    }

}

int slow_bitmap_and(unsigned long *dst, const unsigned long *bitmap1,

                    const unsigned long *bitmap2, int bits)

{

    int k;

    int nr = BITS_TO_LONGS(bits);

    unsigned long result = 0;

    for (k = 0; k < nr; k++) {

        result |= (dst[k] = bitmap1[k] & bitmap2[k]);

    }

    return result != 0;

}

void slow_bitmap_or(unsigned long *dst, const unsigned long *bitmap1,

                    const unsigned long *bitmap2, int bits)

{

    int k;

    int nr = BITS_TO_LONGS(bits);

    for (k = 0; k < nr; k++) {

        dst[k] = bitmap1[k] | bitmap2[k];

    }

}

void slow_bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,

                     const unsigned long *bitmap2, int bits)

{

    int k;

    int nr = BITS_TO_LONGS(bits);

    for (k = 0; k < nr; k++) {

        dst[k] = bitmap1[k] ^ bitmap2[k];

    }

}

int slow_bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,

                       const unsigned long *bitmap2, int bits)

{

    int k;

    int nr = BITS_TO_LONGS(bits);

    unsigned long result = 0;

    for (k = 0; k < nr; k++) {

        result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);

    }

    return result != 0;

}

#define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) % BITS_PER_LONG))

void bitmap_set(unsigned long *map, int start, int nr)

{

    unsigned long *p = map + BIT_WORD(start);

    const int size = start + nr;

    int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);

    unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);

    while (nr - bits_to_set >= 0) {

        *p |= mask_to_set;

        nr -= bits_to_set;

        bits_to_set = BITS_PER_LONG;

        mask_to_set = ~0UL;

        p++;

    }

    if (nr) {

        mask_to_set &= BITMAP_LAST_WORD_MASK(size);

        *p |= mask_to_set;

    }

}

void bitmap_clear(unsigned long *map, int start, int nr)

{

    unsigned long *p = map + BIT_WORD(start);

    const int size = start + nr;

    int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);

    unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);

    while (nr - bits_to_clear >= 0) {

        *p &= ~mask_to_clear;

        nr -= bits_to_clear;

        bits_to_clear = BITS_PER_LONG;

        mask_to_clear = ~0UL;

        p++;

    }

    if (nr) {

        mask_to_clear &= BITMAP_LAST_WORD_MASK(size);

        *p &= ~mask_to_clear;

    }

}

#define ALIGN_MASK(x,mask)      (((x)+(mask))&~(mask))

/**

 * bitmap_find_next_zero_area - find a contiguous aligned zero area

 * @map: The address to base the search on

 * @size: The bitmap size in bits

 * @start: The bitnumber to start searching at

 * @nr: The number of zeroed bits we're looking for

 * @align_mask: Alignment mask for zero area

 *

 * The @align_mask should be one less than a power of 2; the effect is that

 * the bit offset of all zero areas this function finds is multiples of that

 * power of 2. A @align_mask of 0 means no alignment is required.

 */

unsigned long bitmap_find_next_zero_area(unsigned long *map,

                                         unsigned long size,

                                         unsigned long start,

                                         unsigned int nr,

                                         unsigned long align_mask)

{

    unsigned long index, end, i;

again:

    index = find_next_zero_bit(map, size, start);

    /* Align allocation */

    index = ALIGN_MASK(index, align_mask);

    end = index + nr;

    if (end > size) {

        return end;

    }

    i = find_next_bit(map, end, index);

    if (i < end) {

        start = i + 1;

        goto again;

    }

    return index;

}

int slow_bitmap_intersects(const unsigned long *bitmap1,

                           const unsigned long *bitmap2, int bits)

{

    int k, lim = bits/BITS_PER_LONG;

    for (k = 0; k < lim; ++k) {

        if (bitmap1[k] & bitmap2[k]) {

            return 1;

        }

    }

    if (bits % BITS_PER_LONG) {

        if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits)) {

            return 1;

        }

    }

    return 0;

}