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); \ 30 out: \ 31 sz; \ 32 }) 33 34 unsigned 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 39 unsigned 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 } 44