[linux-2.6-block.git] / lib / find_bit.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* 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.
 */

#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) || \
		!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);
}
EXPORT_SYMBOL(find_next_bit);
#endif

#ifndef find_next_zero_bit
unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
				 unsigned long offset)
{
	return _find_next_bit(addr, NULL, size, offset, ~0UL);
}
EXPORT_SYMBOL(find_next_zero_bit);
#endif

#if !defined(find_next_and_bit)
unsigned 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);
}
EXPORT_SYMBOL(find_next_and_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_bit
unsigned 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 inline unsigned long _find_next_bit_le(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 &= 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 = addr1[start / BITS_PER_LONG];
		if (addr2)
			tmp &= addr2[start / BITS_PER_LONG];
		tmp ^= invert;
	}

	return min(start + __ffs(ext2_swab(tmp)), nbits);
}
#endif

#ifndef find_next_zero_bit_le
unsigned long find_next_zero_bit_le(const void *addr, unsigned
		long size, unsigned long offset)
{
	return _find_next_bit_le(addr, NULL, size, offset, ~0UL);
}
EXPORT_SYMBOL(find_next_zero_bit_le);
#endif

#ifndef find_next_bit_le
unsigned long find_next_bit_le(const void *addr, unsigned
		long size, unsigned long offset)
{
	return _find_next_bit_le(addr, NULL, size, offset, 0UL);
}
EXPORT_SYMBOL(find_next_bit_le);
#endif

#endif /* __BIG_ENDIAN */
Commit	Line	Data
	1	// SPDX-License-Identifier: GPL-2.0-or-later
	2	/* bit search implementation
	3	*
	4	* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
	5	* Written by David Howells (dhowells@redhat.com)
	6	*
	7	* Copyright (C) 2008 IBM Corporation
	8	* 'find_last_bit' is written by Rusty Russell <rusty@rustcorp.com.au>
	9	* (Inspired by David Howell's find_next_bit implementation)
	10	*
	11	* Rewritten by Yury Norov <yury.norov@gmail.com> to decrease
	12	* size and improve performance, 2015.
	13	*/
	14
	15	#include <linux/bitops.h>
	16	#include <linux/bitmap.h>
	17	#include <linux/export.h>
	18	#include <linux/kernel.h>
	19
	20	#if !defined(find_next_bit) \|\| !defined(find_next_zero_bit) \|\| \
	21	!defined(find_next_and_bit)
	22
	23	/*
	24	* This is a common helper function for find_next_bit, find_next_zero_bit, and
	25	* find_next_and_bit. The differences are:
	26	* - The "invert" argument, which is XORed with each fetched word before
	27	* searching it for one bits.
	28	* - The optional "addr2", which is anded with "addr1" if present.
	29	*/
	30	static inline unsigned long _find_next_bit(const unsigned long *addr1,
	31	const unsigned long *addr2, unsigned long nbits,
	32	unsigned long start, unsigned long invert)
	33	{
	34	unsigned long tmp;
	35
	36	if (unlikely(start >= nbits))
	37	return nbits;
	38
	39	tmp = addr1[start / BITS_PER_LONG];
	40	if (addr2)
	41	tmp &= addr2[start / BITS_PER_LONG];
	42	tmp ^= invert;
	43
	44	/* Handle 1st word. */
	45	tmp &= BITMAP_FIRST_WORD_MASK(start);
	46	start = round_down(start, BITS_PER_LONG);
	47
	48	while (!tmp) {
	49	start += BITS_PER_LONG;
	50	if (start >= nbits)
	51	return nbits;
	52
	53	tmp = addr1[start / BITS_PER_LONG];
	54	if (addr2)
	55	tmp &= addr2[start / BITS_PER_LONG];
	56	tmp ^= invert;
	57	}
	58
	59	return min(start + __ffs(tmp), nbits);
	60	}
	61	#endif
	62
	63	#ifndef find_next_bit
	64	/*
	65	* Find the next set bit in a memory region.
	66	*/
	67	unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
	68	unsigned long offset)
	69	{
	70	return _find_next_bit(addr, NULL, size, offset, 0UL);
	71	}
	72	EXPORT_SYMBOL(find_next_bit);
	73	#endif
	74
	75	#ifndef find_next_zero_bit
	76	unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
	77	unsigned long offset)
	78	{
	79	return _find_next_bit(addr, NULL, size, offset, ~0UL);
	80	}
	81	EXPORT_SYMBOL(find_next_zero_bit);
	82	#endif
	83
	84	#if !defined(find_next_and_bit)
	85	unsigned long find_next_and_bit(const unsigned long *addr1,
	86	const unsigned long *addr2, unsigned long size,
	87	unsigned long offset)
	88	{
	89	return _find_next_bit(addr1, addr2, size, offset, 0UL);
	90	}
	91	EXPORT_SYMBOL(find_next_and_bit);
	92	#endif
	93
	94	#ifndef find_first_bit
	95	/*
	96	* Find the first set bit in a memory region.
	97	*/
	98	unsigned long find_first_bit(const unsigned long *addr, unsigned long size)
	99	{
	100	unsigned long idx;
	101
	102	for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
	103	if (addr[idx])
	104	return min(idx * BITS_PER_LONG + __ffs(addr[idx]), size);
	105	}
	106
	107	return size;
	108	}
	109	EXPORT_SYMBOL(find_first_bit);
	110	#endif
	111
	112	#ifndef find_first_zero_bit
	113	/*
	114	* Find the first cleared bit in a memory region.
	115	*/
	116	unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size)
	117	{
	118	unsigned long idx;
	119
	120	for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
	121	if (addr[idx] != ~0UL)
	122	return min(idx * BITS_PER_LONG + ffz(addr[idx]), size);
	123	}
	124
	125	return size;
	126	}
	127	EXPORT_SYMBOL(find_first_zero_bit);
	128	#endif
	129
	130	#ifndef find_last_bit
	131	unsigned long find_last_bit(const unsigned long *addr, unsigned long size)
	132	{
	133	if (size) {
	134	unsigned long val = BITMAP_LAST_WORD_MASK(size);
	135	unsigned long idx = (size-1) / BITS_PER_LONG;
	136
	137	do {
	138	val &= addr[idx];
	139	if (val)
	140	return idx * BITS_PER_LONG + __fls(val);
	141
	142	val = ~0ul;
	143	} while (idx--);
	144	}
	145	return size;
	146	}
	147	EXPORT_SYMBOL(find_last_bit);
	148	#endif
	149
	150	#ifdef __BIG_ENDIAN
	151
	152	/* include/linux/byteorder does not support "unsigned long" type */
	153	static inline unsigned long ext2_swab(const unsigned long y)
	154	{
	155	#if BITS_PER_LONG == 64
	156	return (unsigned long) __swab64((u64) y);
	157	#elif BITS_PER_LONG == 32
	158	return (unsigned long) __swab32((u32) y);
	159	#else
	160	#error BITS_PER_LONG not defined
	161	#endif
	162	}
	163
	164	#if !defined(find_next_bit_le) \|\| !defined(find_next_zero_bit_le)
	165	static inline unsigned long _find_next_bit_le(const unsigned long *addr1,
	166	const unsigned long *addr2, unsigned long nbits,
	167	unsigned long start, unsigned long invert)
	168	{
	169	unsigned long tmp;
	170
	171	if (unlikely(start >= nbits))
	172	return nbits;
	173
	174	tmp = addr1[start / BITS_PER_LONG];
	175	if (addr2)
	176	tmp &= addr2[start / BITS_PER_LONG];
	177	tmp ^= invert;
	178
	179	/* Handle 1st word. */
	180	tmp &= ext2_swab(BITMAP_FIRST_WORD_MASK(start));
	181	start = round_down(start, BITS_PER_LONG);
	182
	183	while (!tmp) {
	184	start += BITS_PER_LONG;
	185	if (start >= nbits)
	186	return nbits;
	187
	188	tmp = addr1[start / BITS_PER_LONG];
	189	if (addr2)
	190	tmp &= addr2[start / BITS_PER_LONG];
	191	tmp ^= invert;
	192	}
	193
	194	return min(start + __ffs(ext2_swab(tmp)), nbits);
	195	}
	196	#endif
	197
	198	#ifndef find_next_zero_bit_le
	199	unsigned long find_next_zero_bit_le(const void *addr, unsigned
	200	long size, unsigned long offset)
	201	{
	202	return _find_next_bit_le(addr, NULL, size, offset, ~0UL);
	203	}
	204	EXPORT_SYMBOL(find_next_zero_bit_le);
	205	#endif
	206
	207	#ifndef find_next_bit_le
	208	unsigned long find_next_bit_le(const void *addr, unsigned
	209	long size, unsigned long offset)
	210	{
	211	return _find_next_bit_le(addr, NULL, size, offset, 0UL);
	212	}
	213	EXPORT_SYMBOL(find_next_bit_le);
	214	#endif
	215
	216	#endif /* __BIG_ENDIAN */