/* bit search implementation * * 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/export.h>#include <linux/kernel.h> #if !defined(find_next_bit) || !defined(find_next_zero_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 (!nbits || 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);}EXPORT_SYMBOL(find_next_bit);#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);}EXPORT_SYMBOL(find_next_zero_bit);#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;}EXPORT_SYMBOL(find_first_bit);#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;}EXPORT_SYMBOL(find_first_zero_bit);#endif #ifndef find_last_bitunsigned long find_last_bit(const unsigned long *addr, unsigned long size){	if (size) {		unsigned long val = BITMAP_LAST_WORD_MASK(size);		unsigned long idx = (size-1) / BITS_PER_LONG; 		do {			val &= addr[idx];			if (val)				return idx * BITS_PER_LONG + __fls(val); 			val = ~0ul;		} while (idx--);	}	return size;}EXPORT_SYMBOL(find_last_bit);#endif #ifdef __BIG_ENDIAN /* include/linux/byteorder does not support "unsigned long" type */static inline unsigned long ext2_swab(const unsigned long y){#if BITS_PER_LONG == 64	return (unsigned long) __swab64((u64) y);#elif BITS_PER_LONG == 32	return (unsigned long) __swab32((u32) y);#else#error BITS_PER_LONG not defined#endif} #if !defined(find_next_bit_le) || !defined(find_next_zero_bit_le)static unsigned long _find_next_bit_le(const unsigned long *addr,		unsigned long nbits, unsigned long start, unsigned long invert){	unsigned long tmp; 	if (!nbits || start >= nbits)		return nbits; 	tmp = addr[start / BITS_PER_LONG] ^ invert; 	/* Handle 1st word. */	tmp &= ext2_swab(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(ext2_swab(tmp)), nbits);}#endif #ifndef find_next_zero_bit_leunsigned long find_next_zero_bit_le(const void *addr, unsigned		long size, unsigned long offset){	return _find_next_bit_le(addr, size, offset, ~0UL);}EXPORT_SYMBOL(find_next_zero_bit_le);#endif #ifndef find_next_bit_leunsigned long find_next_bit_le(const void *addr, unsigned		long size, unsigned long offset){	return _find_next_bit_le(addr, size, offset, 0UL);}EXPORT_SYMBOL(find_next_bit_le);#endif #endif /* __BIG_ENDIAN */