linux-brain/include/linux/bitmap.h

/* SPDX-License-Identifier: GPL-2.0 */
#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_find_next_zero_area_off(buf, len, pos, n, mask)	as above
 * 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_parse(buf, buflen, dst, nbits)	Parse bitmap dst from kernel buf
 * bitmap_parse_user(ubuf, ulen, dst, nbits)	Parse bitmap dst from user buf
 * bitmap_parselist(buf, dst, nbits)		Parse bitmap dst from kernel buf
 * bitmap_parselist_user(buf, dst, nbits)	Parse bitmap dst from user buf
 * 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_u32array(dst, nbits, buf, nwords) *dst = *buf (nwords 32b words)
 * bitmap_to_u32array(buf, nwords, src, nbits)	*buf = *dst (nwords 32b words)
 */

/*
 * 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.
 */
extern unsigned long *bitmap_alloc(unsigned int nbits, gfp_t flags);
extern unsigned long *bitmap_zalloc(unsigned int nbits, gfp_t flags);
extern void bitmap_free(const unsigned long *bitmap);

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

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

extern unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
						    unsigned long size,
						    unsigned long start,
						    unsigned int nr,
						    unsigned long align_mask,
						    unsigned long align_offset);

/**
 * 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.
 */
static inline unsigned long
bitmap_find_next_zero_area(unsigned long *map,
			   unsigned long size,
			   unsigned long start,
			   unsigned int nr,
			   unsigned long align_mask)
{
	return bitmap_find_next_zero_area_off(map, size, start, nr,
					      align_mask, 0);
}

extern int __bitmap_parse(const char *buf, unsigned int buflen, int is_user,
			unsigned long *dst, int nbits);
extern int bitmap_parse_user(const char __user *ubuf, unsigned int ulen,
			unsigned long *dst, int nbits);
extern int bitmap_parselist(const char *buf, unsigned long *maskp,
			int nmaskbits);
extern int bitmap_parselist_user(const char __user *ubuf, unsigned int ulen,
			unsigned long *dst, int nbits);
extern void bitmap_remap(unsigned long *dst, const unsigned long *src,
		const unsigned long *old, const unsigned long *new, unsigned int nbits);
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, unsigned int bits);
extern void bitmap_fold(unsigned long *dst, const unsigned long *orig,
		unsigned int sz, unsigned int nbits);
extern int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order);
extern void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order);
extern int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order);
extern unsigned int bitmap_from_u32array(unsigned long *bitmap,
					 unsigned int nbits,
					 const u32 *buf,
					 unsigned int nwords);
extern unsigned int bitmap_to_u32array(u32 *buf,
				       unsigned int nwords,
				       const unsigned long *bitmap,
				       unsigned int nbits);
#ifdef __BIG_ENDIAN
extern void bitmap_copy_le(unsigned long *dst, const unsigned long *src, unsigned int nbits);
#else
#define bitmap_copy_le bitmap_copy
#endif
extern unsigned int bitmap_ord_to_pos(const unsigned long *bitmap, unsigned int ord, unsigned int nbits);
extern int bitmap_print_to_pagebuf(bool list, char *buf,
				   const unsigned long *maskp, int nmaskbits);

#define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 1)))
#define BITMAP_LAST_WORD_MASK(nbits) (~0UL >> (-(nbits) & (BITS_PER_LONG - 1)))

/*
 * The static inlines below do not handle constant nbits==0 correctly,
 * so make such users (should any ever turn up) call the out-of-line
 * versions.
 */
#define small_const_nbits(nbits) \
	(__builtin_constant_p(nbits) && (nbits) <= BITS_PER_LONG && (nbits) > 0)

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

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

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

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

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

#ifdef __LITTLE_ENDIAN
#define BITMAP_MEM_ALIGNMENT 8
#else
#define BITMAP_MEM_ALIGNMENT (8 * sizeof(unsigned long))
#endif
#define BITMAP_MEM_MASK (BITMAP_MEM_ALIGNMENT - 1)

static inline int bitmap_equal(const unsigned long *src1,
			const unsigned long *src2, unsigned int nbits)
{
	if (small_const_nbits(nbits))
		return !((*src1 ^ *src2) & BITMAP_LAST_WORD_MASK(nbits));
	if (__builtin_constant_p(nbits & BITMAP_MEM_MASK) &&
	    IS_ALIGNED(nbits, BITMAP_MEM_ALIGNMENT))
		return !memcmp(src1, src2, nbits / 8);
	return __bitmap_equal(src1, src2, nbits);
}

static inline int bitmap_intersects(const unsigned long *src1,
			const unsigned long *src2, unsigned 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, unsigned 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, unsigned nbits)
{
	if (small_const_nbits(nbits))
		return ! (*src & BITMAP_LAST_WORD_MASK(nbits));

	return find_first_bit(src, nbits) == nbits;
}

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

	return find_first_zero_bit(src, nbits) == nbits;
}

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

static __always_inline void bitmap_set(unsigned long *map, unsigned int start,
		unsigned int nbits)
{
	if (__builtin_constant_p(nbits) && nbits == 1)
		__set_bit(start, map);
	else if (__builtin_constant_p(start & BITMAP_MEM_MASK) &&
		 IS_ALIGNED(start, BITMAP_MEM_ALIGNMENT) &&
		 __builtin_constant_p(nbits & BITMAP_MEM_MASK) &&
		 IS_ALIGNED(nbits, BITMAP_MEM_ALIGNMENT))
		memset((char *)map + start / 8, 0xff, nbits / 8);
	else
		__bitmap_set(map, start, nbits);
}

static __always_inline void bitmap_clear(unsigned long *map, unsigned int start,
		unsigned int nbits)
{
	if (__builtin_constant_p(nbits) && nbits == 1)
		__clear_bit(start, map);
	else if (__builtin_constant_p(start & BITMAP_MEM_MASK) &&
		 IS_ALIGNED(start, BITMAP_MEM_ALIGNMENT) &&
		 __builtin_constant_p(nbits & BITMAP_MEM_MASK) &&
		 IS_ALIGNED(nbits, BITMAP_MEM_ALIGNMENT))
		memset((char *)map + start / 8, 0, nbits / 8);
	else
		__bitmap_clear(map, start, nbits);
}

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

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

static inline int bitmap_parse(const char *buf, unsigned int buflen,
			unsigned long *maskp, int nmaskbits)
{
	return __bitmap_parse(buf, buflen, 0, maskp, nmaskbits);
}

/*
 * BITMAP_FROM_U64() - Represent u64 value in the format suitable for bitmap.
 *
 * 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)
{
	dst[0] = mask & ULONG_MAX;

	if (sizeof(mask) > sizeof(unsigned long))
		dst[1] = mask >> 32;
}

#endif /* __ASSEMBLY__ */

#endif /* __LINUX_BITMAP_H */