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/*

 * lib/bitmap.c

 * Helper functions for bitmap.h.

 *

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

 * Version 2.  See the file COPYING for more details.

 */

#include 

#include 

//#include 

#include 

#include 

#include 

#include 

#include 

//#include 

/*

 * 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.  See the big-endian headers

 * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h

 * for the best explanations of this ordering.

 */

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

{

	unsigned 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;

}

EXPORT_SYMBOL(__bitmap_empty);

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

{

	unsigned 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;

}

EXPORT_SYMBOL(__bitmap_full);

int __bitmap_equal(const unsigned long *bitmap1,

		const unsigned long *bitmap2, unsigned int bits)

{

	unsigned 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;

}

EXPORT_SYMBOL(__bitmap_equal);

void __bitmap_complement(unsigned long *dst, const unsigned long *src, unsigned int bits)

{

	unsigned 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];

}

EXPORT_SYMBOL(__bitmap_complement);

/**

 * __bitmap_shift_right - logical right shift of the bits in a bitmap

 *   @dst : destination bitmap

 *   @src : source bitmap

 *   @shift : shift by this many bits

 *   @bits : bitmap size, in bits

 *

 * Shifting right (dividing) means moving bits in the MS -> LS bit

 * direction.  Zeros are fed into the vacated MS positions and the

 * LS bits shifted off the bottom are lost.

 */

void __bitmap_shift_right(unsigned long *dst,

			const unsigned long *src, int shift, int bits)

{

	int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG;

	int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;

	unsigned long mask = (1UL << left) - 1;

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

		unsigned long upper, lower;

		/*

		 * If shift is not word aligned, take lower rem bits of

		 * word above and make them the top rem bits of result.

		 */

		if (!rem || off + k + 1 >= lim)

			upper = 0;

		else {

			upper = src[off + k + 1];

			if (off + k + 1 == lim - 1 && left)

				upper &= mask;

		}

		lower = src[off + k];

		if (left && off + k == lim - 1)

			lower &= mask;

		dst[k] = upper << (BITS_PER_LONG - rem) | lower >> rem;

		if (left && k == lim - 1)

			dst[k] &= mask;

	}

	if (off)

		memset(&dst[lim - off], 0, off*sizeof(unsigned long));

}

EXPORT_SYMBOL(__bitmap_shift_right);

/**

 * __bitmap_shift_left - logical left shift of the bits in a bitmap

 *   @dst : destination bitmap

 *   @src : source bitmap

 *   @shift : shift by this many bits

 *   @bits : bitmap size, in bits

 *

 * Shifting left (multiplying) means moving bits in the LS -> MS

 * direction.  Zeros are fed into the vacated LS bit positions

 * and those MS bits shifted off the top are lost.

 */

void __bitmap_shift_left(unsigned long *dst,

			const unsigned long *src, int shift, int bits)

{

	int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG;

	int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;

	for (k = lim - off - 1; k >= 0; --k) {

		unsigned long upper, lower;

		/*

		 * If shift is not word aligned, take upper rem bits of

		 * word below and make them the bottom rem bits of result.

		 */

		if (rem && k > 0)

			lower = src[k - 1];

		else

			lower = 0;

		upper = src[k];

		if (left && k == lim - 1)

			upper &= (1UL << left) - 1;

		dst[k + off] = lower  >> (BITS_PER_LONG - rem) | upper << rem;

		if (left && k + off == lim - 1)

			dst[k + off] &= (1UL << left) - 1;

	}

	if (off)

		memset(dst, 0, off*sizeof(unsigned long));

}

EXPORT_SYMBOL(__bitmap_shift_left);

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

				const unsigned long *bitmap2, unsigned int bits)

{

	unsigned int k;

	unsigned int lim = bits/BITS_PER_LONG;

	unsigned long result = 0;

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

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

	if (bits % BITS_PER_LONG)

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

			   BITMAP_LAST_WORD_MASK(bits));

	return result != 0;

}

EXPORT_SYMBOL(__bitmap_and);

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

				const unsigned long *bitmap2, unsigned int bits)

{

	unsigned int k;

	unsigned int nr = BITS_TO_LONGS(bits);

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

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

}

EXPORT_SYMBOL(__bitmap_or);

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

				const unsigned long *bitmap2, unsigned int bits)

{

	unsigned int k;

	unsigned int nr = BITS_TO_LONGS(bits);

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

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

}

EXPORT_SYMBOL(__bitmap_xor);

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

				const unsigned long *bitmap2, unsigned int bits)

{

	unsigned int k;

	unsigned int lim = bits/BITS_PER_LONG;

	unsigned long result = 0;

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

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

	if (bits % BITS_PER_LONG)

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

			   BITMAP_LAST_WORD_MASK(bits));

	return result != 0;

}

EXPORT_SYMBOL(__bitmap_andnot);

int __bitmap_intersects(const unsigned long *bitmap1,

			const unsigned long *bitmap2, unsigned int bits)

{

	unsigned 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;

}

EXPORT_SYMBOL(__bitmap_intersects);

int __bitmap_subset(const unsigned long *bitmap1,

		    const unsigned long *bitmap2, unsigned int bits)

{

	unsigned 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;

}

EXPORT_SYMBOL(__bitmap_subset);

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

{

	unsigned int k, lim = bits/BITS_PER_LONG;

	int w = 0;

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

		w += hweight_long(bitmap[k]);

	if (bits % BITS_PER_LONG)

		w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));

	return w;

}

EXPORT_SYMBOL(__bitmap_weight);

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

{

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

	const unsigned int size = start + len;

	int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);

	unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);

	while (len - bits_to_set >= 0) {

		*p |= mask_to_set;

		len -= bits_to_set;

		bits_to_set = BITS_PER_LONG;

		mask_to_set = ~0UL;

		p++;

	}

	if (len) {

		mask_to_set &= BITMAP_LAST_WORD_MASK(size);

		*p |= mask_to_set;

	}

}

EXPORT_SYMBOL(bitmap_set);

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

{

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

	const unsigned int size = start + len;

	int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);

	unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);

	while (len - bits_to_clear >= 0) {

		*p &= ~mask_to_clear;

		len -= bits_to_clear;

		bits_to_clear = BITS_PER_LONG;

		mask_to_clear = ~0UL;

		p++;

	}

	if (len) {

		mask_to_clear &= BITMAP_LAST_WORD_MASK(size);

		*p &= ~mask_to_clear;

	}

}

EXPORT_SYMBOL(bitmap_clear);

/*

 * 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;

}

EXPORT_SYMBOL(bitmap_find_next_zero_area);

/*

 * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers,

 * second version by Paul Jackson, third by Joe Korty.

 */

#define CHUNKSZ				32

#define nbits_to_hold_value(val)	fls(val)

#define BASEDEC 10		/* fancier cpuset lists input in decimal */

/**

 * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap

 *	@buf: pointer to a bitmap

 *	@pos: a bit position in @buf (0 <= @pos < @bits)

 *	@bits: number of valid bit positions in @buf

 *

 * Map the bit at position @pos in @buf (of length @bits) to the

 * ordinal of which set bit it is.  If it is not set or if @pos

 * is not a valid bit position, map to -1.

 *

 * If for example, just bits 4 through 7 are set in @buf, then @pos

 * values 4 through 7 will get mapped to 0 through 3, respectively,

 * and other @pos values will get mapped to -1.  When @pos value 7

 * gets mapped to (returns) @ord value 3 in this example, that means

 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.

 *

 * The bit positions 0 through @bits are valid positions in @buf.

 */

static int bitmap_pos_to_ord(const unsigned long *buf, int pos, int bits)

{

	int i, ord;

	if (pos < 0 || pos >= bits || !test_bit(pos, buf))

		return -1;

	i = find_first_bit(buf, bits);

	ord = 0;

	while (i < pos) {

		i = find_next_bit(buf, bits, i + 1);

	     	ord++;

	}

	BUG_ON(i != pos);

	return ord;

}

/**

 * bitmap_ord_to_pos - find position of n-th set bit in bitmap

 *	@buf: pointer to bitmap

 *	@ord: ordinal bit position (n-th set bit, n >= 0)

 *	@bits: number of valid bit positions in @buf

 *

 * Map the ordinal offset of bit @ord in @buf to its position in @buf.

 * Value of @ord should be in range 0 <= @ord < weight(buf), else

 * results are undefined.

 *

 * If for example, just bits 4 through 7 are set in @buf, then @ord

 * values 0 through 3 will get mapped to 4 through 7, respectively,

 * and all other @ord values return undefined values.  When @ord value 3

 * gets mapped to (returns) @pos value 7 in this example, that means

 * that the 3rd set bit (starting with 0th) is at position 7 in @buf.

 *

 * The bit positions 0 through @bits are valid positions in @buf.

 */

int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits)

{

	int pos = 0;

	if (ord >= 0 && ord < bits) {

		int i;

		for (i = find_first_bit(buf, bits);

		     i < bits && ord > 0;

		     i = find_next_bit(buf, bits, i + 1))

	     		ord--;

		if (i < bits && ord == 0)

			pos = i;

	}

	return pos;

}

/**

 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap

 *	@dst: remapped result

 *	@src: subset to be remapped

 *	@old: defines domain of map

 *	@new: defines range of map

 *	@bits: number of bits in each of these bitmaps

 *

 * Let @old and @new define a mapping of bit positions, such that

 * whatever position is held by the n-th set bit in @old is mapped

 * to the n-th set bit in @new.  In the more general case, allowing

 * for the possibility that the weight 'w' of @new is less than the

 * weight of @old, map the position of the n-th set bit in @old to

 * the position of the m-th set bit in @new, where m == n % w.

 *

 * If either of the @old and @new bitmaps are empty, or if @src and

 * @dst point to the same location, then this routine copies @src

 * to @dst.

 *

 * The positions of unset bits in @old are mapped to themselves

 * (the identify map).

 *

 * Apply the above specified mapping to @src, placing the result in

 * @dst, clearing any bits previously set in @dst.

 *

 * For example, lets say that @old has bits 4 through 7 set, and

 * @new has bits 12 through 15 set.  This defines the mapping of bit

 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other

 * bit positions unchanged.  So if say @src comes into this routine

 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,

 * 13 and 15 set.

 */

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

		const unsigned long *old, const unsigned long *new,

		int bits)

{

	int oldbit, w;

	if (dst == src)		/* following doesn't handle inplace remaps */

		return;

	bitmap_zero(dst, bits);

	w = bitmap_weight(new, bits);

	for_each_set_bit(oldbit, src, bits) {

	     	int n = bitmap_pos_to_ord(old, oldbit, bits);

		if (n < 0 || w == 0)

			set_bit(oldbit, dst);	/* identity map */

		else

			set_bit(bitmap_ord_to_pos(new, n % w, bits), dst);

	}

}

EXPORT_SYMBOL(bitmap_remap);

/**

 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit

 *	@oldbit: bit position to be mapped

 *	@old: defines domain of map

 *	@new: defines range of map

 *	@bits: number of bits in each of these bitmaps

 *

 * Let @old and @new define a mapping of bit positions, such that

 * whatever position is held by the n-th set bit in @old is mapped

 * to the n-th set bit in @new.  In the more general case, allowing

 * for the possibility that the weight 'w' of @new is less than the

 * weight of @old, map the position of the n-th set bit in @old to

 * the position of the m-th set bit in @new, where m == n % w.

 *

 * The positions of unset bits in @old are mapped to themselves

 * (the identify map).

 *

 * Apply the above specified mapping to bit position @oldbit, returning

 * the new bit position.

 *

 * For example, lets say that @old has bits 4 through 7 set, and

 * @new has bits 12 through 15 set.  This defines the mapping of bit

 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other

 * bit positions unchanged.  So if say @oldbit is 5, then this routine

 * returns 13.

 */

int bitmap_bitremap(int oldbit, const unsigned long *old,

				const unsigned long *new, int bits)

{

	int w = bitmap_weight(new, bits);

	int n = bitmap_pos_to_ord(old, oldbit, bits);

	if (n < 0 || w == 0)

		return oldbit;

	else

		return bitmap_ord_to_pos(new, n % w, bits);

}

EXPORT_SYMBOL(bitmap_bitremap);

/**

 * bitmap_onto - translate one bitmap relative to another

 *	@dst: resulting translated bitmap

 * 	@orig: original untranslated bitmap

 * 	@relmap: bitmap relative to which translated

 *	@bits: number of bits in each of these bitmaps

 *

 * Set the n-th bit of @dst iff there exists some m such that the

 * n-th bit of @relmap is set, the m-th bit of @orig is set, and

 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.

 * (If you understood the previous sentence the first time your

 * read it, you're overqualified for your current job.)

 *

 * In other words, @orig is mapped onto (surjectively) @dst,

 * using the the map {  | the n-th bit of @relmap is the

 * m-th set bit of @relmap }.

 *

 * Any set bits in @orig above bit number W, where W is the

 * weight of (number of set bits in) @relmap are mapped nowhere.

 * In particular, if for all bits m set in @orig, m >= W, then

 * @dst will end up empty.  In situations where the possibility

 * of such an empty result is not desired, one way to avoid it is

 * to use the bitmap_fold() operator, below, to first fold the

 * @orig bitmap over itself so that all its set bits x are in the

 * range 0 <= x < W.  The bitmap_fold() operator does this by

 * setting the bit (m % W) in @dst, for each bit (m) set in @orig.

 *

 * Example [1] for bitmap_onto():

 *  Let's say @relmap has bits 30-39 set, and @orig has bits

 *  1, 3, 5, 7, 9 and 11 set.  Then on return from this routine,

 *  @dst will have bits 31, 33, 35, 37 and 39 set.

 *

 *  When bit 0 is set in @orig, it means turn on the bit in

 *  @dst corresponding to whatever is the first bit (if any)

 *  that is turned on in @relmap.  Since bit 0 was off in the

 *  above example, we leave off that bit (bit 30) in @dst.

 *

 *  When bit 1 is set in @orig (as in the above example), it

 *  means turn on the bit in @dst corresponding to whatever

 *  is the second bit that is turned on in @relmap.  The second

 *  bit in @relmap that was turned on in the above example was

 *  bit 31, so we turned on bit 31 in @dst.

 *

 *  Similarly, we turned on bits 33, 35, 37 and 39 in @dst,

 *  because they were the 4th, 6th, 8th and 10th set bits

 *  set in @relmap, and the 4th, 6th, 8th and 10th bits of

 *  @orig (i.e. bits 3, 5, 7 and 9) were also set.

 *

 *  When bit 11 is set in @orig, it means turn on the bit in

 *  @dst corresponding to whatever is the twelfth bit that is

 *  turned on in @relmap.  In the above example, there were

 *  only ten bits turned on in @relmap (30..39), so that bit

 *  11 was set in @orig had no affect on @dst.

 *

 * Example [2] for bitmap_fold() + bitmap_onto():

 *  Let's say @relmap has these ten bits set:

 *		40 41 42 43 45 48 53 61 74 95

 *  (for the curious, that's 40 plus the first ten terms of the

 *  Fibonacci sequence.)

 *

 *  Further lets say we use the following code, invoking

 *  bitmap_fold() then bitmap_onto, as suggested above to

 *  avoid the possitility of an empty @dst result:

 *

 *	unsigned long *tmp;	// a temporary bitmap's bits

 *

 *	bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);

 *	bitmap_onto(dst, tmp, relmap, bits);

 *

 *  Then this table shows what various values of @dst would be, for

 *  various @orig's.  I list the zero-based positions of each set bit.

 *  The tmp column shows the intermediate result, as computed by

 *  using bitmap_fold() to fold the @orig bitmap modulo ten

 *  (the weight of @relmap).

 *

 *      @orig           tmp            @dst

 *      0                0             40

 *      1                1             41

 *      9                9             95

 *      10               0             40 (*)

 *      1 3 5 7          1 3 5 7       41 43 48 61

 *      0 1 2 3 4        0 1 2 3 4     40 41 42 43 45

 *      0 9 18 27        0 9 8 7       40 61 74 95

 *      0 10 20 30       0             40

 *      0 11 22 33       0 1 2 3       40 41 42 43

 *      0 12 24 36       0 2 4 6       40 42 45 53

 *      78 102 211       1 2 8         41 42 74 (*)

 *

 * (*) For these marked lines, if we hadn't first done bitmap_fold()

 *     into tmp, then the @dst result would have been empty.

 *

 * If either of @orig or @relmap is empty (no set bits), then @dst

 * will be returned empty.

 *

 * If (as explained above) the only set bits in @orig are in positions

 * m where m >= W, (where W is the weight of @relmap) then @dst will

 * once again be returned empty.

 *

 * All bits in @dst not set by the above rule are cleared.

 */

void bitmap_onto(unsigned long *dst, const unsigned long *orig,

			const unsigned long *relmap, int bits)

{

	int n, m;       	/* same meaning as in above comment */

	if (dst == orig)	/* following doesn't handle inplace mappings */

		return;

	bitmap_zero(dst, bits);

	/*

	 * The following code is a more efficient, but less

	 * obvious, equivalent to the loop:

	 *	for (m = 0; m < bitmap_weight(relmap, bits); m++) {

	 *		n = bitmap_ord_to_pos(orig, m, bits);

	 *		if (test_bit(m, orig))

	 *			set_bit(n, dst);

	 *	}

	 */

	m = 0;

	for_each_set_bit(n, relmap, bits) {

		/* m == bitmap_pos_to_ord(relmap, n, bits) */

		if (test_bit(m, orig))

			set_bit(n, dst);

		m++;

	}

}

EXPORT_SYMBOL(bitmap_onto);

/**

 * bitmap_fold - fold larger bitmap into smaller, modulo specified size

 *	@dst: resulting smaller bitmap

 *	@orig: original larger bitmap

 *	@sz: specified size

 *	@bits: number of bits in each of these bitmaps

 *

 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.

 * Clear all other bits in @dst.  See further the comment and

 * Example [2] for bitmap_onto() for why and how to use this.

 */

void bitmap_fold(unsigned long *dst, const unsigned long *orig,

			int sz, int bits)

{

	int oldbit;

	if (dst == orig)	/* following doesn't handle inplace mappings */

		return;

	bitmap_zero(dst, bits);

	for_each_set_bit(oldbit, orig, bits)

		set_bit(oldbit % sz, dst);

}

EXPORT_SYMBOL(bitmap_fold);

/*

 * Common code for bitmap_*_region() routines.

 *	bitmap: array of unsigned longs corresponding to the bitmap

 *	pos: the beginning of the region

 *	order: region size (log base 2 of number of bits)

 *	reg_op: operation(s) to perform on that region of bitmap

 *

 * Can set, verify and/or release a region of bits in a bitmap,

 * depending on which combination of REG_OP_* flag bits is set.

 *

 * A region of a bitmap is a sequence of bits in the bitmap, of

 * some size '1 << order' (a power of two), aligned to that same

 * '1 << order' power of two.

 *

 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).

 * Returns 0 in all other cases and reg_ops.

 */

enum {

	REG_OP_ISFREE,		/* true if region is all zero bits */

	REG_OP_ALLOC,		/* set all bits in region */

	REG_OP_RELEASE,		/* clear all bits in region */

};

static int __reg_op(unsigned long *bitmap, unsigned int pos, int order, int reg_op)

{

	int nbits_reg;		/* number of bits in region */

	int index;		/* index first long of region in bitmap */

	int offset;		/* bit offset region in bitmap[index] */

	int nlongs_reg;		/* num longs spanned by region in bitmap */

	int nbitsinlong;	/* num bits of region in each spanned long */

	unsigned long mask;	/* bitmask for one long of region */

	int i;			/* scans bitmap by longs */

	int ret = 0;		/* return value */

	/*

	 * Either nlongs_reg == 1 (for small orders that fit in one long)

	 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)

	 */

	nbits_reg = 1 << order;

	index = pos / BITS_PER_LONG;

	offset = pos - (index * BITS_PER_LONG);

	nlongs_reg = BITS_TO_LONGS(nbits_reg);

	nbitsinlong = min(nbits_reg,  BITS_PER_LONG);

	/*

	 * Can't do "mask = (1UL << nbitsinlong) - 1", as that

	 * overflows if nbitsinlong == BITS_PER_LONG.

	 */

	mask = (1UL << (nbitsinlong - 1));

	mask += mask - 1;

	mask <<= offset;

	switch (reg_op) {

	case REG_OP_ISFREE:

		for (i = 0; i < nlongs_reg; i++) {

			if (bitmap[index + i] & mask)

				goto done;

		}

		ret = 1;	/* all bits in region free (zero) */

		break;

	case REG_OP_ALLOC:

		for (i = 0; i < nlongs_reg; i++)

			bitmap[index + i] |= mask;

		break;

	case REG_OP_RELEASE:

		for (i = 0; i < nlongs_reg; i++)

			bitmap[index + i] &= ~mask;

		break;

	}

done:

	return ret;

}

/**

 * bitmap_find_free_region - find a contiguous aligned mem region

 *	@bitmap: array of unsigned longs corresponding to the bitmap

 *	@bits: number of bits in the bitmap

 *	@order: region size (log base 2 of number of bits) to find

 *

 * Find a region of free (zero) bits in a @bitmap of @bits bits and

 * allocate them (set them to one).  Only consider regions of length

 * a power (@order) of two, aligned to that power of two, which

 * makes the search algorithm much faster.

 *

 * Return the bit offset in bitmap of the allocated region,

 * or -errno on failure.

 */

int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order)

{

	unsigned int pos, end;		/* scans bitmap by regions of size order */

	for (pos = 0 ; (end = pos + (1U << order)) <= bits; pos = end) {

		if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))

			continue;

		__reg_op(bitmap, pos, order, REG_OP_ALLOC);

		return pos;

	}

	return -ENOMEM;

}

EXPORT_SYMBOL(bitmap_find_free_region);

/**

 * bitmap_release_region - release allocated bitmap region

 *	@bitmap: array of unsigned longs corresponding to the bitmap

 *	@pos: beginning of bit region to release

 *	@order: region size (log base 2 of number of bits) to release

 *

 * This is the complement to __bitmap_find_free_region() and releases

 * the found region (by clearing it in the bitmap).

 *

 * No return value.

 */

void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order)

{

	__reg_op(bitmap, pos, order, REG_OP_RELEASE);

}

EXPORT_SYMBOL(bitmap_release_region);

/**

 * bitmap_allocate_region - allocate bitmap region

 *	@bitmap: array of unsigned longs corresponding to the bitmap

 *	@pos: beginning of bit region to allocate

 *	@order: region size (log base 2 of number of bits) to allocate

 *

 * Allocate (set bits in) a specified region of a bitmap.

 *

 * Return 0 on success, or %-EBUSY if specified region wasn't

 * free (not all bits were zero).

 */

int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order)

{

	if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))

		return -EBUSY;

	return __reg_op(bitmap, pos, order, REG_OP_ALLOC);

}

EXPORT_SYMBOL(bitmap_allocate_region);

/**

 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.

 * @dst:   destination buffer

 * @src:   bitmap to copy

 * @nbits: number of bits in the bitmap

 *

 * Require nbits % BITS_PER_LONG == 0.

 */

void bitmap_copy_le(void *dst, const unsigned long *src, int nbits)

{

	unsigned long *d = dst;

	int i;

	for (i = 0; i < nbits/BITS_PER_LONG; i++) {

		if (BITS_PER_LONG == 64)

			d[i] = cpu_to_le64(src[i]);

		else

			d[i] = cpu_to_le32(src[i]);

	}

}

EXPORT_SYMBOL(bitmap_copy_le);