include/linux/bitmap.h

// SPDX-License-Identifier: GPL-2.0+
#ifndef __LINUX_BITMAP_H
#define __LINUX_BITMAP_H

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

#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)

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

static inline 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];
}

static inline 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;
}

static inline 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;
	}
}

static inline 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;
	}
}

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 unsigned long
find_next_bit(const unsigned long *addr, unsigned long size,
	      unsigned long offset)
{
	const unsigned long *p = addr + BIT_WORD(offset);
	unsigned long result = offset & ~(BITS_PER_LONG - 1);
	unsigned long tmp;

	if (offset >= size)
		return size;
	size -= result;
	offset %= BITS_PER_LONG;
	if (offset) {
		tmp = *(p++);
		tmp &= (~0UL << offset);
		if (size < BITS_PER_LONG)
			goto found_first;
		if (tmp)
			goto found_middle;
		size -= BITS_PER_LONG;
		result += BITS_PER_LONG;
	}
	while (size & ~(BITS_PER_LONG - 1)) {
		tmp = *(p++);
		if ((tmp))
			goto found_middle;
		result += BITS_PER_LONG;
		size -= BITS_PER_LONG;
	}
	if (!size)
		return result;
	tmp = *p;

found_first:
	tmp &= (~0UL >> (BITS_PER_LONG - size));
	if (tmp == 0UL)		/* Are any bits set? */
		return result + size;	/* Nope. */
found_middle:
	return result + __ffs(tmp);
}

/*
 * Find the first set bit in a memory region.
 */
static inline unsigned long find_first_bit(const unsigned long *addr, unsigned long size)
{
	unsigned long idx;

	for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
		if (addr[idx])
			return min(idx * BITS_PER_LONG + __ffs(addr[idx]), size);
	}

	return size;
}

#define for_each_set_bit(bit, addr, size) \
	for ((bit) = find_first_bit((addr), (size));		\
	     (bit) < (size);					\
	     (bit) = find_next_bit((addr), (size), (bit) + 1))

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)
{
	unsigned long index, end, i;
again:
	index = find_next_zero_bit(map, size, start);

	/*
	 * Align allocation
	 */
	index = (index + align_mask) & ~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;
}

static inline void bitmap_fill(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, 0xff, len);
	}
}

static inline bool 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 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 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 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 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);
}

#endif /* __LINUX_BITMAP_H */