path: root/include/linux/bitmap.h

/* SPDX-License-Identifier: GPL-2.0-only */

#ifndef __LINUX_BITMAP_H
#define __LINUX_BITMAP_H

#ifndef __ASSEMBLY__

#include <linux/types.h>
#include <linux/bitops.h>
#include <linux/string.h>
#include <linux/kernel.h>

/*
 * bitmaps provide bit arrays that consume one or more unsigned
 * longs.  The bitmap interface and available operations are listed
 * here, in bitmap.h
 *
 * Function implementations generic to all architectures are in
 * lib/bitmap.c.  Functions implementations that are architecture
 * specific are in various include/asm-<arch>/bitops.h headers
 * and other arch/<arch> specific files.
 *
 * See lib/bitmap.c for more details.
 */

/*
 * The available bitmap operations and their rough meaning in the
 * case that the bitmap is a single unsigned long are thus:
 *
 * Note that nbits should be always a compile time evaluable constant.
 * Otherwise many inlines will generate horrible code.
 *
 * bitmap_zero(dst, nbits)			*dst = 0UL
 * bitmap_fill(dst, nbits)			*dst = ~0UL
 * bitmap_copy(dst, src, nbits)			*dst = *src
 * bitmap_and(dst, src1, src2, nbits)		*dst = *src1 & *src2
 * bitmap_or(dst, src1, src2, nbits)		*dst = *src1 | *src2
 * bitmap_xor(dst, src1, src2, nbits)		*dst = *src1 ^ *src2
 * bitmap_andnot(dst, src1, src2, nbits)	*dst = *src1 & ~(*src2)
 * bitmap_complement(dst, src, nbits)		*dst = ~(*src)
 * bitmap_equal(src1, src2, nbits)		Are *src1 and *src2 equal?
 * bitmap_intersects(src1, src2, nbits) 	Do *src1 and *src2 overlap?
 * bitmap_subset(src1, src2, nbits)		Is *src1 a subset of *src2?
 * bitmap_empty(src, nbits)			Are all bits zero in *src?
 * bitmap_full(src, nbits)			Are all bits set in *src?
 * bitmap_weight(src, nbits)			Hamming Weight: number set bits
 * bitmap_set(dst, pos, nbits)			Set specified bit area
 * bitmap_clear(dst, pos, nbits)		Clear specified bit area
 * bitmap_find_next_zero_area(buf, len, pos, n, mask)	Find bit free area
 * bitmap_shift_right(dst, src, n, nbits)	*dst = *src >> n
 * bitmap_shift_left(dst, src, n, nbits)	*dst = *src << n
 * bitmap_remap(dst, src, old, new, nbits)	*dst = map(old, new)(src)
 * bitmap_bitremap(oldbit, old, new, nbits)	newbit = map(old, new)(oldbit)
 * bitmap_onto(dst, orig, relmap, nbits)	*dst = orig relative to relmap
 * bitmap_fold(dst, orig, sz, nbits)		dst bits = orig bits mod sz
 * bitmap_find_free_region(bitmap, bits, order)	Find and allocate bit region
 * bitmap_release_region(bitmap, pos, order)	Free specified bit region
 * bitmap_allocate_region(bitmap, pos, order)	Allocate specified bit region
 * bitmap_from_arr32(dst, buf, nbits)           Copy nbits from u32[] buf to dst
 * bitmap_from_arr64(dst, buf, nbits)           Copy nbits from u64[] buf to dst
 * bitmap_to_arr32(buf, src, nbits)             Copy nbits from buf to u32[] dst
 * bitmap_to_arr64(buf, src, nbits)             Copy nbits from buf to u64[] dst
 */

/*
 * Also the following operations in asm/bitops.h apply to bitmaps.
 *
 * set_bit(bit, addr)			*addr |= bit
 * clear_bit(bit, addr)			*addr &= ~bit
 * change_bit(bit, addr)		*addr ^= bit
 * test_bit(bit, addr)			Is bit set in *addr?
 * test_and_set_bit(bit, addr)		Set bit and return old value
 * test_and_clear_bit(bit, addr)	Clear bit and return old value
 * test_and_change_bit(bit, addr)	Change bit and return old value
 * find_first_zero_bit(addr, nbits)	Position first zero bit in *addr
 * find_first_bit(addr, nbits)		Position first set bit in *addr
 * find_next_zero_bit(addr, nbits, bit)	Position next zero bit in *addr >= bit
 * find_next_bit(addr, nbits, bit)	Position next set bit in *addr >= bit
 */

/*
 * The DECLARE_BITMAP(name,bits) macro, in linux/types.h, can be used
 * to declare an array named 'name' of just enough unsigned longs to
 * contain all bit positions from 0 to 'bits' - 1.
 */

/*
 * Allocation and deallocation of bitmap.
 * Provided in lib/bitmap.c to avoid circular dependency.
 */
unsigned long *bitmap_zalloc(unsigned int nbits);
unsigned long *bitmap_xzalloc(unsigned int nbits);

/*
 * lib/bitmap.c provides these functions:
 */

extern int __bitmap_empty(const unsigned long *bitmap, int bits);
extern int __bitmap_full(const unsigned long *bitmap, int bits);
extern int __bitmap_equal(const unsigned long *bitmap1,
			const unsigned long *bitmap2, int bits);
extern void __bitmap_complement(unsigned long *dst, const unsigned long *src,
			int bits);
extern void __bitmap_shift_right(unsigned long *dst,
                        const unsigned long *src, int shift, int bits);
extern void __bitmap_shift_left(unsigned long *dst,
                        const unsigned long *src, int shift, int bits);
extern int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
			const unsigned long *bitmap2, int bits);
extern void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
			const unsigned long *bitmap2, int bits);
extern void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
			const unsigned long *bitmap2, int bits);
extern int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
			const unsigned long *bitmap2, int bits);
extern int __bitmap_intersects(const unsigned long *bitmap1,
			const unsigned long *bitmap2, int bits);
extern int __bitmap_subset(const unsigned long *bitmap1,
			const unsigned long *bitmap2, int bits);
extern int __bitmap_weight(const unsigned long *bitmap, int bits);

extern void bitmap_set(unsigned long *map, int i, int len);
extern void bitmap_clear(unsigned long *map, int start, int nr);
extern unsigned long bitmap_find_next_zero_area(unsigned long *map,
					 unsigned long size,
					 unsigned long start,
					 unsigned int nr,
					 unsigned long align_mask);

extern void bitmap_remap(unsigned long *dst, const unsigned long *src,
		const unsigned long *old, const unsigned long *new, int bits);
extern int bitmap_bitremap(int oldbit,
		const unsigned long *old, const unsigned long *new, int bits);
extern void bitmap_onto(unsigned long *dst, const unsigned long *orig,
		const unsigned long *relmap, int bits);
extern void bitmap_fold(unsigned long *dst, const unsigned long *orig,
		int sz, int bits);
extern int bitmap_find_free_region(unsigned long *bitmap, int bits, int order);
extern void bitmap_release_region(unsigned long *bitmap, int pos, int order);
extern int bitmap_allocate_region(unsigned long *bitmap, int pos, int order);
extern void bitmap_copy_le(void *dst, const unsigned long *src, int nbits);
extern int bitmap_ord_to_pos(const unsigned long *bitmap, int n, int bits);

#define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) % BITS_PER_LONG))
#define BITMAP_LAST_WORD_MASK(nbits)					\
(									\
	((nbits) % BITS_PER_LONG) ?					\
		(1UL<<((nbits) % BITS_PER_LONG))-1 : ~0UL		\
)

#define small_const_nbits(nbits) \
	(__builtin_constant_p(nbits) && (nbits) <= BITS_PER_LONG)

static inline void bitmap_zero(unsigned long *dst, int nbits)
{
	if (small_const_nbits(nbits))
		*dst = 0UL;
	else {
		int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
		memset(dst, 0, len);
	}
}

static inline void bitmap_fill(unsigned long *dst, int nbits)
{
	size_t nlongs = BITS_TO_LONGS(nbits);
	if (!small_const_nbits(nbits)) {
		int len = (nlongs - 1) * sizeof(unsigned long);
		memset(dst, 0xff,  len);
	}
	dst[nlongs - 1] = BITMAP_LAST_WORD_MASK(nbits);
}

static inline void bitmap_copy(unsigned long *dst, const unsigned long *src,
			int nbits)
{
	if (small_const_nbits(nbits))
		*dst = *src;
	else {
		int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
		memcpy(dst, src, len);
	}
}

/*
 * Copy bitmap and clear tail bits in last word.
 */
static inline void bitmap_copy_clear_tail(unsigned long *dst,
		const unsigned long *src, unsigned int nbits)
{
	bitmap_copy(dst, src, nbits);
	if (nbits % BITS_PER_LONG)
		dst[nbits / BITS_PER_LONG] &= BITMAP_LAST_WORD_MASK(nbits);
}

/*
 * On 32-bit systems bitmaps are represented as u32 arrays internally. On LE64
 * machines the order of hi and lo parts of numbers match the bitmap structure.
 * In both cases conversion is not needed when copying data from/to arrays of
 * u32. But in LE64 case, typecast in bitmap_copy_clear_tail() may lead
 * to out-of-bound access. To avoid that, both LE and BE variants of 64-bit
 * architectures are not using bitmap_copy_clear_tail().
 */
#if BITS_PER_LONG == 64
void bitmap_from_arr32(unsigned long *bitmap, const u32 *buf,
							unsigned int nbits);
void bitmap_to_arr32(u32 *buf, const unsigned long *bitmap,
							unsigned int nbits);
#else
#define bitmap_from_arr32(bitmap, buf, nbits)			\
	bitmap_copy_clear_tail((unsigned long *) (bitmap),	\
			(const unsigned long *) (buf), (nbits))
#define bitmap_to_arr32(buf, bitmap, nbits)			\
	bitmap_copy_clear_tail((unsigned long *) (buf),		\
			(const unsigned long *) (bitmap), (nbits))
#endif

/*
 * On 64-bit systems bitmaps are represented as u64 arrays internally. On LE32
 * machines the order of hi and lo parts of numbers match the bitmap structure.
 * In both cases conversion is not needed when copying data from/to arrays of
 * u64.
 */
#if (BITS_PER_LONG == 32) && defined(__BIG_ENDIAN)
void bitmap_from_arr64(unsigned long *bitmap, const u64 *buf, unsigned int nbits);
void bitmap_to_arr64(u64 *buf, const unsigned long *bitmap, unsigned int nbits);
#else
#define bitmap_from_arr64(bitmap, buf, nbits)			\
	bitmap_copy_clear_tail((unsigned long *)(bitmap), (const unsigned long *)(buf), (nbits))
#define bitmap_to_arr64(buf, bitmap, nbits)			\
	bitmap_copy_clear_tail((unsigned long *)(buf), (const unsigned long *)(bitmap), (nbits))
#endif

/**
 * BITMAP_FROM_U64() - Represent u64 value in the format suitable for bitmap.
 * @n: u64 value
 *
 * Linux bitmaps are internally arrays of unsigned longs, i.e. 32-bit
 * integers in 32-bit environment, and 64-bit integers in 64-bit one.
 *
 * There are four combinations of endianness and length of the word in linux
 * ABIs: LE64, BE64, LE32 and BE32.
 *
 * On 64-bit kernels 64-bit LE and BE numbers are naturally ordered in
 * bitmaps and therefore don't require any special handling.
 *
 * On 32-bit kernels 32-bit LE ABI orders lo word of 64-bit number in memory
 * prior to hi, and 32-bit BE orders hi word prior to lo. The bitmap on the
 * other hand is represented as an array of 32-bit words and the position of
 * bit N may therefore be calculated as: word #(N/32) and bit #(N%32) in that
 * word.  For example, bit #42 is located at 10th position of 2nd word.
 * It matches 32-bit LE ABI, and we can simply let the compiler store 64-bit
 * values in memory as it usually does. But for BE we need to swap hi and lo
 * words manually.
 *
 * With all that, the macro BITMAP_FROM_U64() does explicit reordering of hi and
 * lo parts of u64.  For LE32 it does nothing, and for BE environment it swaps
 * hi and lo words, as is expected by bitmap.
 */
#if BITS_PER_LONG == 64
#define BITMAP_FROM_U64(n) (n)
#else
#define BITMAP_FROM_U64(n) ((unsigned long) ((u64)(n) & ULONG_MAX)), \
				((unsigned long) ((u64)(n) >> 32))
#endif

/**
 * bitmap_from_u64 - Check and swap words within u64.
 *  @mask: source bitmap
 *  @dst:  destination bitmap
 *
 * In 32-bit Big Endian kernel, when using ``(u32 *)(&val)[*]``
 * to read u64 mask, we will get the wrong word.
 * That is ``(u32 *)(&val)[0]`` gets the upper 32 bits,
 * but we expect the lower 32-bits of u64.
 */
static inline void bitmap_from_u64(unsigned long *dst, u64 mask)
{
	bitmap_from_arr64(dst, &mask, 64);
}

static inline int bitmap_and(unsigned long *dst, const unsigned long *src1,
			const unsigned long *src2, int nbits)
{
	if (small_const_nbits(nbits))
		return (*dst = *src1 & *src2) != 0;
	return __bitmap_and(dst, src1, src2, nbits);
}

static inline void bitmap_or(unsigned long *dst, const unsigned long *src1,
			const unsigned long *src2, int nbits)
{
	if (small_const_nbits(nbits))
		*dst = *src1 | *src2;
	else
		__bitmap_or(dst, src1, src2, nbits);
}

static inline void bitmap_xor(unsigned long *dst, const unsigned long *src1,
			const unsigned long *src2, int nbits)
{
	if (small_const_nbits(nbits))
		*dst = *src1 ^ *src2;
	else
		__bitmap_xor(dst, src1, src2, nbits);
}

static inline int bitmap_andnot(unsigned long *dst, const unsigned long *src1,
			const unsigned long *src2, int nbits)
{
	if (small_const_nbits(nbits))
		return (*dst = *src1 & ~(*src2)) != 0;
	return __bitmap_andnot(dst, src1, src2, nbits);
}

static inline void bitmap_complement(unsigned long *dst, const unsigned long *src,
			int nbits)
{
	if (small_const_nbits(nbits))
		*dst = ~(*src) & BITMAP_LAST_WORD_MASK(nbits);
	else
		__bitmap_complement(dst, src, nbits);
}

static inline int bitmap_equal(const unsigned long *src1,
			const unsigned long *src2, int nbits)
{
	if (small_const_nbits(nbits))
		return ! ((*src1 ^ *src2) & BITMAP_LAST_WORD_MASK(nbits));
	else
		return __bitmap_equal(src1, src2, nbits);
}

static inline int bitmap_intersects(const unsigned long *src1,
			const unsigned long *src2, int nbits)
{
	if (small_const_nbits(nbits))
		return ((*src1 & *src2) & BITMAP_LAST_WORD_MASK(nbits)) != 0;
	else
		return __bitmap_intersects(src1, src2, nbits);
}

static inline int bitmap_subset(const unsigned long *src1,
			const unsigned long *src2, int nbits)
{
	if (small_const_nbits(nbits))
		return ! ((*src1 & ~(*src2)) & BITMAP_LAST_WORD_MASK(nbits));
	else
		return __bitmap_subset(src1, src2, nbits);
}

static inline int bitmap_empty(const unsigned long *src, int nbits)
{
	if (small_const_nbits(nbits))
		return ! (*src & BITMAP_LAST_WORD_MASK(nbits));
	else
		return __bitmap_empty(src, nbits);
}

static inline int bitmap_full(const unsigned long *src, int nbits)
{
	if (small_const_nbits(nbits))
		return ! (~(*src) & BITMAP_LAST_WORD_MASK(nbits));
	else
		return __bitmap_full(src, nbits);
}

static inline int bitmap_weight(const unsigned long *src, int nbits)
{
	if (small_const_nbits(nbits))
		return hweight_long(*src & BITMAP_LAST_WORD_MASK(nbits));
	return __bitmap_weight(src, nbits);
}

static inline void bitmap_shift_right(unsigned long *dst,
			const unsigned long *src, int n, int nbits)
{
	if (small_const_nbits(nbits))
		*dst = *src >> n;
	else
		__bitmap_shift_right(dst, src, n, nbits);
}

static inline void bitmap_shift_left(unsigned long *dst,
			const unsigned long *src, int n, int nbits)
{
	if (small_const_nbits(nbits))
		*dst = (*src << n) & BITMAP_LAST_WORD_MASK(nbits);
	else
		__bitmap_shift_left(dst, src, n, nbits);
}

#endif /* __ASSEMBLY__ */

#endif /* __LINUX_BITMAP_H */