// SPDX-License-Identifier: GPL-2.0-or-later/* bit search implementation * * Copied from lib/find_bit.c to tools/lib/find_bit.c * * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) * * Copyright (C) 2008 IBM Corporation * 'find_last_bit' is written by Rusty Russell <rusty@rustcorp.com.au> * (Inspired by David Howell's find_next_bit implementation) * * Rewritten by Yury Norov <yury.norov@gmail.com> to decrease * size and improve performance, 2015. */ #include <linux/bitops.h>#include <linux/bitmap.h>#include <linux/kernel.h> #if !defined(find_next_bit) || !defined(find_next_zero_bit) || \		!defined(find_next_and_bit) /* * This is a common helper function for find_next_bit, find_next_zero_bit, and * find_next_and_bit. The differences are: *  - The "invert" argument, which is XORed with each fetched word before *    searching it for one bits. *  - The optional "addr2", which is anded with "addr1" if present. */static inline unsigned long _find_next_bit(const unsigned long *addr1,		const unsigned long *addr2, unsigned long nbits,		unsigned long start, unsigned long invert){	unsigned long tmp; 	if (unlikely(start >= nbits))		return nbits; 	tmp = addr1[start / BITS_PER_LONG];	if (addr2)		tmp &= addr2[start / BITS_PER_LONG];	tmp ^= invert; 	/* Handle 1st word. */	tmp &= BITMAP_FIRST_WORD_MASK(start);	start = round_down(start, BITS_PER_LONG); 	while (!tmp) {		start += BITS_PER_LONG;		if (start >= nbits)			return nbits; 		tmp = addr1[start / BITS_PER_LONG];		if (addr2)			tmp &= addr2[start / BITS_PER_LONG];		tmp ^= invert;	} 	return min(start + __ffs(tmp), nbits);}#endif #ifndef find_next_bit/* * Find the next set bit in a memory region. */unsigned long find_next_bit(const unsigned long *addr, unsigned long size,			    unsigned long offset){	return _find_next_bit(addr, NULL, size, offset, 0UL);}#endif #ifndef find_first_bit/* * Find the first set bit in a memory region. */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;}#endif #ifndef find_first_zero_bit/* * Find the first cleared bit in a memory region. */unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size){	unsigned long idx; 	for (idx = 0; idx * BITS_PER_LONG < size; idx++) {		if (addr[idx] != ~0UL)			return min(idx * BITS_PER_LONG + ffz(addr[idx]), size);	} 	return size;}#endif #ifndef find_next_zero_bitunsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,				 unsigned long offset){	return _find_next_bit(addr, NULL, size, offset, ~0UL);}#endif #ifndef find_next_and_bitunsigned long find_next_and_bit(const unsigned long *addr1,		const unsigned long *addr2, unsigned long size,		unsigned long offset){	return _find_next_bit(addr1, addr2, size, offset, 0UL);}#endif