[linux-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/math.h>
#include <linux/minmax.h>
#include <linux/swab.h>

/*
 * Common helper for find_bit() function family
 * @FETCH: The expression that fetches and pre-processes each word of bitmap(s)
 * @MUNGE: The expression that post-processes a word containing found bit (may be empty)
 * @size: The bitmap size in bits
 */
#define FIND_FIRST_BIT(FETCH, MUNGE, size)					\
({										\
	unsigned long idx, val, sz = (size);					\
										\
	for (idx = 0; idx * BITS_PER_LONG < sz; idx++) {			\
		val = (FETCH);							\
		if (val) {							\
			sz = min(idx * BITS_PER_LONG + __ffs(MUNGE(val)), sz);	\
			break;							\
		}								\
	}									\
										\
	sz;									\
})

/*
 * Common helper for find_next_bit() function family
 * @FETCH: The expression that fetches and pre-processes each word of bitmap(s)
 * @MUNGE: The expression that post-processes a word containing found bit (may be empty)
 * @size: The bitmap size in bits
 * @start: The bitnumber to start searching at
 */
#define FIND_NEXT_BIT(FETCH, MUNGE, size, start)				\
({										\
	unsigned long mask, idx, tmp, sz = (size), __start = (start);		\
										\
	if (unlikely(__start >= sz))						\
		goto out;							\
										\
	mask = MUNGE(BITMAP_FIRST_WORD_MASK(__start));				\
	idx = __start / BITS_PER_LONG;						\
										\
	for (tmp = (FETCH) & mask; !tmp; tmp = (FETCH)) {			\
		if ((idx + 1) * BITS_PER_LONG >= sz)				\
			goto out;						\
		idx++;								\
	}									\
										\
	sz = min(idx * BITS_PER_LONG + __ffs(MUNGE(tmp)), sz);			\
out:										\
	sz;									\
})

#define FIND_NTH_BIT(FETCH, size, num)						\
({										\
	unsigned long sz = (size), nr = (num), idx, w, tmp;			\
										\
	for (idx = 0; (idx + 1) * BITS_PER_LONG <= sz; idx++) {			\
		if (idx * BITS_PER_LONG + nr >= sz)				\
			goto out;						\
										\
		tmp = (FETCH);							\
		w = hweight_long(tmp);						\
		if (w > nr)							\
			goto found;						\
										\
		nr -= w;							\
	}									\
										\
	if (sz % BITS_PER_LONG)							\
		tmp = (FETCH) & BITMAP_LAST_WORD_MASK(sz);			\
found:										\
	sz = idx * BITS_PER_LONG + fns(tmp, nr);				\
out:										\
	sz;									\
})

#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)
{
	return FIND_FIRST_BIT(addr[idx], /* nop */, size);
}
EXPORT_SYMBOL(_find_first_bit);
#endif

#ifndef find_first_and_bit
/*
 * Find the first set bit in two memory regions.
 */
unsigned long _find_first_and_bit(const unsigned long *addr1,
				  const unsigned long *addr2,
				  unsigned long size)
{
	return FIND_FIRST_BIT(addr1[idx] & addr2[idx], /* nop */, size);
}
EXPORT_SYMBOL(_find_first_and_bit);
#endif

/*
 * Find the first set bit in three memory regions.
 */
unsigned long _find_first_and_and_bit(const unsigned long *addr1,
				      const unsigned long *addr2,
				      const unsigned long *addr3,
				      unsigned long size)
{
	return FIND_FIRST_BIT(addr1[idx] & addr2[idx] & addr3[idx], /* nop */, size);
}
EXPORT_SYMBOL(_find_first_and_and_bit);

#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)
{
	return FIND_FIRST_BIT(~addr[idx], /* nop */, size);
}
EXPORT_SYMBOL(_find_first_zero_bit);
#endif

#ifndef find_next_bit
unsigned long _find_next_bit(const unsigned long *addr, unsigned long nbits, unsigned long start)
{
	return FIND_NEXT_BIT(addr[idx], /* nop */, nbits, start);
}
EXPORT_SYMBOL(_find_next_bit);
#endif

unsigned long __find_nth_bit(const unsigned long *addr, unsigned long size, unsigned long n)
{
	return FIND_NTH_BIT(addr[idx], size, n);
}
EXPORT_SYMBOL(__find_nth_bit);

unsigned long __find_nth_and_bit(const unsigned long *addr1, const unsigned long *addr2,
				 unsigned long size, unsigned long n)
{
	return FIND_NTH_BIT(addr1[idx] & addr2[idx], size, n);
}
EXPORT_SYMBOL(__find_nth_and_bit);

unsigned long __find_nth_andnot_bit(const unsigned long *addr1, const unsigned long *addr2,
				 unsigned long size, unsigned long n)
{
	return FIND_NTH_BIT(addr1[idx] & ~addr2[idx], size, n);
}
EXPORT_SYMBOL(__find_nth_andnot_bit);

unsigned long __find_nth_and_andnot_bit(const unsigned long *addr1,
					const unsigned long *addr2,
					const unsigned long *addr3,
					unsigned long size, unsigned long n)
{
	return FIND_NTH_BIT(addr1[idx] & addr2[idx] & ~addr3[idx], size, n);
}
EXPORT_SYMBOL(__find_nth_and_andnot_bit);

#ifndef find_next_and_bit
unsigned long _find_next_and_bit(const unsigned long *addr1, const unsigned long *addr2,
					unsigned long nbits, unsigned long start)
{
	return FIND_NEXT_BIT(addr1[idx] & addr2[idx], /* nop */, nbits, start);
}
EXPORT_SYMBOL(_find_next_and_bit);
#endif

#ifndef find_next_andnot_bit
unsigned long _find_next_andnot_bit(const unsigned long *addr1, const unsigned long *addr2,
					unsigned long nbits, unsigned long start)
{
	return FIND_NEXT_BIT(addr1[idx] & ~addr2[idx], /* nop */, nbits, start);
}
EXPORT_SYMBOL(_find_next_andnot_bit);
#endif

#ifndef find_next_or_bit
unsigned long _find_next_or_bit(const unsigned long *addr1, const unsigned long *addr2,
					unsigned long nbits, unsigned long start)
{
	return FIND_NEXT_BIT(addr1[idx] | addr2[idx], /* nop */, nbits, start);
}
EXPORT_SYMBOL(_find_next_or_bit);
#endif

#ifndef find_next_zero_bit
unsigned long _find_next_zero_bit(const unsigned long *addr, unsigned long nbits,
					 unsigned long start)
{
	return FIND_NEXT_BIT(~addr[idx], /* nop */, nbits, start);
}
EXPORT_SYMBOL(_find_next_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

unsigned long find_next_clump8(unsigned long *clump, const unsigned long *addr,
			       unsigned long size, unsigned long offset)
{
	offset = find_next_bit(addr, size, offset);
	if (offset == size)
		return size;

	offset = round_down(offset, 8);
	*clump = bitmap_get_value8(addr, offset);

	return offset;
}
EXPORT_SYMBOL(find_next_clump8);

#ifdef __BIG_ENDIAN

#ifndef find_first_zero_bit_le
/*
 * Find the first cleared bit in an LE memory region.
 */
unsigned long _find_first_zero_bit_le(const unsigned long *addr, unsigned long size)
{
	return FIND_FIRST_BIT(~addr[idx], swab, size);
}
EXPORT_SYMBOL(_find_first_zero_bit_le);

#endif

#ifndef find_next_zero_bit_le
unsigned long _find_next_zero_bit_le(const unsigned long *addr,
					unsigned long size, unsigned long offset)
{
	return FIND_NEXT_BIT(~addr[idx], swab, size, offset);
}
EXPORT_SYMBOL(_find_next_zero_bit_le);
#endif

#ifndef find_next_bit_le
unsigned long _find_next_bit_le(const unsigned long *addr,
				unsigned long size, unsigned long offset)
{
	return FIND_NEXT_BIT(addr[idx], swab, size, offset);
}
EXPORT_SYMBOL(_find_next_bit_le);

#endif

#endif /* __BIG_ENDIAN */
Commit	Line	Data
2874c5fd	1	// SPDX-License-Identifier: GPL-2.0-or-later
8f6f19dd	2	/* bit search implementation
1da177e4 LT	3	*
	4	* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
	5	* Written by David Howells (dhowells@redhat.com)
	6	*
8f6f19dd YN	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	*
2c57a0e2 YN	11	* Rewritten by Yury Norov <yury.norov@gmail.com> to decrease
2c57a0e2 YN	12	* size and improve performance, 2015.
1da177e4 LT	13	*/
	14
	15	#include <linux/bitops.h>
8f6f19dd	16	#include <linux/bitmap.h>
8bc3bcc9	17	#include <linux/export.h>
aa6159ab	18	#include <linux/math.h>
b296a6d5	19	#include <linux/minmax.h>
aa6159ab	20	#include <linux/swab.h>
1da177e4	21
58414bbb YN	22	/*
	23	* Common helper for find_bit() function family
	24	* @FETCH: The expression that fetches and pre-processes each word of bitmap(s)
	25	* @MUNGE: The expression that post-processes a word containing found bit (may be empty)
	26	* @size: The bitmap size in bits
	27	*/
	28	#define FIND_FIRST_BIT(FETCH, MUNGE, size) \
	29	({ \
	30	unsigned long idx, val, sz = (size); \
	31	\
	32	for (idx = 0; idx * BITS_PER_LONG < sz; idx++) { \
	33	val = (FETCH); \
	34	if (val) { \
	35	sz = min(idx * BITS_PER_LONG + __ffs(MUNGE(val)), sz); \
	36	break; \
	37	} \
	38	} \
	39	\
	40	sz; \
	41	})
	42
64970b68	43	/*
e79864f3 YN	44	* Common helper for find_next_bit() function family
	45	* @FETCH: The expression that fetches and pre-processes each word of bitmap(s)
	46	* @MUNGE: The expression that post-processes a word containing found bit (may be empty)
	47	* @size: The bitmap size in bits
	48	* @start: The bitnumber to start searching at
c7f612cd	49	*/
e79864f3 YN	50	#define FIND_NEXT_BIT(FETCH, MUNGE, size, start) \
	51	({ \
	52	unsigned long mask, idx, tmp, sz = (size), __start = (start); \
	53	\
	54	if (unlikely(__start >= sz)) \
	55	goto out; \
	56	\
	57	mask = MUNGE(BITMAP_FIRST_WORD_MASK(__start)); \
	58	idx = __start / BITS_PER_LONG; \
	59	\
	60	for (tmp = (FETCH) & mask; !tmp; tmp = (FETCH)) { \
	61	if ((idx + 1) * BITS_PER_LONG >= sz) \
	62	goto out; \
	63	idx++; \
	64	} \
	65	\
	66	sz = min(idx * BITS_PER_LONG + __ffs(MUNGE(tmp)), sz); \
	67	out: \
	68	sz; \
	69	})
0ade34c3	70
3cea8d47 YN	71	#define FIND_NTH_BIT(FETCH, size, num) \
	72	({ \
	73	unsigned long sz = (size), nr = (num), idx, w, tmp; \
	74	\
	75	for (idx = 0; (idx + 1) * BITS_PER_LONG <= sz; idx++) { \
	76	if (idx * BITS_PER_LONG + nr >= sz) \
	77	goto out; \
	78	\
	79	tmp = (FETCH); \
	80	w = hweight_long(tmp); \
	81	if (w > nr) \
	82	goto found; \
	83	\
	84	nr -= w; \
	85	} \
	86	\
	87	if (sz % BITS_PER_LONG) \
	88	tmp = (FETCH) & BITMAP_LAST_WORD_MASK(sz); \
	89	found: \
0b2811ba	90	sz = idx * BITS_PER_LONG + fns(tmp, nr); \
3cea8d47 YN	91	out: \
	92	sz; \
	93	})
	94
19de85ef	95	#ifndef find_first_bit
77b9bd9c AH	96	/*
	97	* Find the first set bit in a memory region.
	98	*/
2cc7b6a4	99	unsigned long _find_first_bit(const unsigned long *addr, unsigned long size)
77b9bd9c	100	{
58414bbb	101	return FIND_FIRST_BIT(addr[idx], /* nop */, size);
77b9bd9c	102	}
2cc7b6a4	103	EXPORT_SYMBOL(_find_first_bit);
19de85ef	104	#endif
77b9bd9c	105
f68edc92 YN	106	#ifndef find_first_and_bit
	107	/*
	108	* Find the first set bit in two memory regions.
	109	*/
	110	unsigned long _find_first_and_bit(const unsigned long *addr1,
	111	const unsigned long *addr2,
	112	unsigned long size)
	113	{
58414bbb	114	return FIND_FIRST_BIT(addr1[idx] & addr2[idx], /* nop */, size);
f68edc92 YN	115	}
	116	EXPORT_SYMBOL(_find_first_and_bit);
	117	#endif
	118
cdc66553 DL	119	/*
	120	* Find the first set bit in three memory regions.
	121	*/
	122	unsigned long _find_first_and_and_bit(const unsigned long *addr1,
	123	const unsigned long *addr2,
	124	const unsigned long *addr3,
	125	unsigned long size)
	126	{
	127	return FIND_FIRST_BIT(addr1[idx] & addr2[idx] & addr3[idx], /* nop */, size);
	128	}
	129	EXPORT_SYMBOL(_find_first_and_and_bit);
	130
19de85ef	131	#ifndef find_first_zero_bit
77b9bd9c AH	132	/*
	133	* Find the first cleared bit in a memory region.
	134	*/
2cc7b6a4	135	unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size)
77b9bd9c	136	{
58414bbb	137	return FIND_FIRST_BIT(~addr[idx], /* nop */, size);
77b9bd9c	138	}
2cc7b6a4	139	EXPORT_SYMBOL(_find_first_zero_bit);
19de85ef	140	#endif
930ae745	141
e79864f3 YN	142	#ifndef find_next_bit
	143	unsigned long _find_next_bit(const unsigned long *addr, unsigned long nbits, unsigned long start)
	144	{
	145	return FIND_NEXT_BIT(addr[idx], /* nop */, nbits, start);
	146	}
	147	EXPORT_SYMBOL(_find_next_bit);
	148	#endif
	149
3cea8d47 YN	150	unsigned long __find_nth_bit(const unsigned long *addr, unsigned long size, unsigned long n)
	151	{
	152	return FIND_NTH_BIT(addr[idx], size, n);
	153	}
	154	EXPORT_SYMBOL(__find_nth_bit);
	155
	156	unsigned long __find_nth_and_bit(const unsigned long addr1, const unsigned long addr2,
	157	unsigned long size, unsigned long n)
	158	{
	159	return FIND_NTH_BIT(addr1[idx] & addr2[idx], size, n);
	160	}
	161	EXPORT_SYMBOL(__find_nth_and_bit);
	162
	163	unsigned long __find_nth_andnot_bit(const unsigned long addr1, const unsigned long addr2,
	164	unsigned long size, unsigned long n)
	165	{
	166	return FIND_NTH_BIT(addr1[idx] & ~addr2[idx], size, n);
	167	}
	168	EXPORT_SYMBOL(__find_nth_andnot_bit);
	169
43245117 YN	170	unsigned long __find_nth_and_andnot_bit(const unsigned long *addr1,
	171	const unsigned long *addr2,
	172	const unsigned long *addr3,
	173	unsigned long size, unsigned long n)
	174	{
	175	return FIND_NTH_BIT(addr1[idx] & addr2[idx] & ~addr3[idx], size, n);
	176	}
	177	EXPORT_SYMBOL(__find_nth_and_andnot_bit);
	178
e79864f3 YN	179	#ifndef find_next_and_bit
	180	unsigned long _find_next_and_bit(const unsigned long addr1, const unsigned long addr2,
	181	unsigned long nbits, unsigned long start)
	182	{
	183	return FIND_NEXT_BIT(addr1[idx] & addr2[idx], /* nop */, nbits, start);
	184	}
	185	EXPORT_SYMBOL(_find_next_and_bit);
	186	#endif
	187
90d48290 VS	188	#ifndef find_next_andnot_bit
	189	unsigned long _find_next_andnot_bit(const unsigned long addr1, const unsigned long addr2,
	190	unsigned long nbits, unsigned long start)
	191	{
	192	return FIND_NEXT_BIT(addr1[idx] & ~addr2[idx], /* nop */, nbits, start);
	193	}
	194	EXPORT_SYMBOL(_find_next_andnot_bit);
	195	#endif
	196
1470afef DC	197	#ifndef find_next_or_bit
	198	unsigned long _find_next_or_bit(const unsigned long addr1, const unsigned long addr2,
	199	unsigned long nbits, unsigned long start)
	200	{
	201	return FIND_NEXT_BIT(addr1[idx] \| addr2[idx], /* nop */, nbits, start);
	202	}
	203	EXPORT_SYMBOL(_find_next_or_bit);
	204	#endif
	205
e79864f3 YN	206	#ifndef find_next_zero_bit
	207	unsigned long _find_next_zero_bit(const unsigned long *addr, unsigned long nbits,
	208	unsigned long start)
	209	{
	210	return FIND_NEXT_BIT(~addr[idx], /* nop */, nbits, start);
	211	}
	212	EXPORT_SYMBOL(_find_next_zero_bit);
	213	#endif
	214
8f6f19dd	215	#ifndef find_last_bit
2cc7b6a4	216	unsigned long _find_last_bit(const unsigned long *addr, unsigned long size)
8f6f19dd YN	217	{
	218	if (size) {
	219	unsigned long val = BITMAP_LAST_WORD_MASK(size);
	220	unsigned long idx = (size-1) / BITS_PER_LONG;
	221
	222	do {
	223	val &= addr[idx];
	224	if (val)
	225	return idx * BITS_PER_LONG + __fls(val);
	226
	227	val = ~0ul;
	228	} while (idx--);
	229	}
	230	return size;
	231	}
2cc7b6a4	232	EXPORT_SYMBOL(_find_last_bit);
8f6f19dd YN	233	#endif
8f6f19dd YN	234
169c474f WBG	235	unsigned long find_next_clump8(unsigned long clump, const unsigned long addr,
	236	unsigned long size, unsigned long offset)
	237	{
	238	offset = find_next_bit(addr, size, offset);
	239	if (offset == size)
	240	return size;
	241
	242	offset = round_down(offset, 8);
	243	*clump = bitmap_get_value8(addr, offset);
	244
	245	return offset;
	246	}
	247	EXPORT_SYMBOL(find_next_clump8);
14a99e13 YN	248
	249	#ifdef __BIG_ENDIAN
	250
	251	#ifndef find_first_zero_bit_le
	252	/*
	253	* Find the first cleared bit in an LE memory region.
	254	*/
	255	unsigned long _find_first_zero_bit_le(const unsigned long *addr, unsigned long size)
	256	{
	257	return FIND_FIRST_BIT(~addr[idx], swab, size);
	258	}
	259	EXPORT_SYMBOL(_find_first_zero_bit_le);
	260
	261	#endif
	262
e79864f3 YN	263	#ifndef find_next_zero_bit_le
	264	unsigned long _find_next_zero_bit_le(const unsigned long *addr,
	265	unsigned long size, unsigned long offset)
	266	{
	267	return FIND_NEXT_BIT(~addr[idx], swab, size, offset);
	268	}
	269	EXPORT_SYMBOL(_find_next_zero_bit_le);
	270	#endif
	271
	272	#ifndef find_next_bit_le
	273	unsigned long _find_next_bit_le(const unsigned long *addr,
	274	unsigned long size, unsigned long offset)
	275	{
	276	return FIND_NEXT_BIT(addr[idx], swab, size, offset);
	277	}
	278	EXPORT_SYMBOL(_find_next_bit_le);
	279
	280	#endif
	281
14a99e13	282	#endif /* __BIG_ENDIAN */