1// SPDX-License-Identifier: GPL-2.0-only
 2#include <linux/bitmap.h>
 3#include <linux/math.h>
 4#include <linux/minmax.h>
 5
 6/*
 7 * Common helper for find_next_bit() function family
 8 * @FETCH: The expression that fetches and pre-processes each word of bitmap(s)
 9 * @MUNGE: The expression that post-processes a word containing found bit (may be empty)
10 * @size: The bitmap size in bits
11 * @start: The bitnumber to start searching at
12 */
13#define FIND_NEXT_BIT(FETCH, MUNGE, size, start)				\
14({										\
15	unsigned long mask, idx, tmp, sz = (size), __start = (start);		\
16										\
17	if (unlikely(__start >= sz))						\
18		goto out;							\
19										\
20	mask = MUNGE(BITMAP_FIRST_WORD_MASK(__start));				\
21	idx = __start / BITS_PER_LONG;						\
22										\
23	for (tmp = (FETCH) & mask; !tmp; tmp = (FETCH)) {			\
24		if ((idx + 1) * BITS_PER_LONG >= sz)				\
25			goto out;						\
26		idx++;								\
27	}									\
28										\
29	sz = min(idx * BITS_PER_LONG + __ffs(MUNGE(tmp)), sz);			\
30out:										\
31	sz;									\
32})
33
34unsigned long _find_next_bit(const unsigned long *addr, unsigned long nbits, unsigned long start)
35{
36	return FIND_NEXT_BIT(addr[idx], /* nop */, nbits, start);
37}
38
39unsigned long _find_next_zero_bit(const unsigned long *addr, unsigned long nbits,
40					 unsigned long start)
41{
42	return FIND_NEXT_BIT(~addr[idx], /* nop */, nbits, start);
43}