/* 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. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #include <linux/bitops.h>#include <linux/bitmap.h>#include <linux/kernel.h> #if !defined(find_next_bit) /* * This is a common helper function for find_next_bit and * find_next_zero_bit.  The difference is the "invert" argument, which * is XORed with each fetched word before searching it for one bits. */static unsigned long _find_next_bit(const unsigned long *addr,		unsigned long nbits, unsigned long start, unsigned long invert){	unsigned long tmp; 	if (unlikely(start >= nbits))		return nbits; 	tmp = addr[start / BITS_PER_LONG] ^ 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 = addr[start / BITS_PER_LONG] ^ 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, 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, size, offset, ~0UL);}#endif