[linux.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 ([email protected])
 *
 * Copyright (C) 2008 IBM Corporation
 * 'find_last_bit' is written by Rusty Russell <[email protected]>
 * (Inspired by David Howell's find_next_bit implementation)
 *
 * Rewritten by Yury Norov <[email protected]> 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 = min(idx * BITS_PER_LONG + fns(tmp, nr), sz);			\
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

#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 ([email protected])
	6	*
8f6f19dd YN	7	* Copyright (C) 2008 IBM Corporation
	8	* 'find_last_bit' is written by Rusty Russell <[email protected]>
	9	* (Inspired by David Howell's find_next_bit implementation)
	10	*
2c57a0e2 YN	11	* Rewritten by Yury Norov <[email protected]> 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: \
	90	sz = min(idx * BITS_PER_LONG + fns(tmp, nr), sz); \
	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
19de85ef	119	#ifndef find_first_zero_bit
77b9bd9c AH	120	/*
	121	* Find the first cleared bit in a memory region.
	122	*/
2cc7b6a4	123	unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size)
77b9bd9c	124	{
58414bbb	125	return FIND_FIRST_BIT(~addr[idx], /* nop */, size);
77b9bd9c	126	}
2cc7b6a4	127	EXPORT_SYMBOL(_find_first_zero_bit);
19de85ef	128	#endif
930ae745	129
e79864f3 YN	130	#ifndef find_next_bit
	131	unsigned long _find_next_bit(const unsigned long *addr, unsigned long nbits, unsigned long start)
	132	{
	133	return FIND_NEXT_BIT(addr[idx], /* nop */, nbits, start);
	134	}
	135	EXPORT_SYMBOL(_find_next_bit);
	136	#endif
	137
3cea8d47 YN	138	unsigned long __find_nth_bit(const unsigned long *addr, unsigned long size, unsigned long n)
	139	{
	140	return FIND_NTH_BIT(addr[idx], size, n);
	141	}
	142	EXPORT_SYMBOL(__find_nth_bit);
	143
	144	unsigned long __find_nth_and_bit(const unsigned long addr1, const unsigned long addr2,
	145	unsigned long size, unsigned long n)
	146	{
	147	return FIND_NTH_BIT(addr1[idx] & addr2[idx], size, n);
	148	}
	149	EXPORT_SYMBOL(__find_nth_and_bit);
	150
	151	unsigned long __find_nth_andnot_bit(const unsigned long addr1, const unsigned long addr2,
	152	unsigned long size, unsigned long n)
	153	{
	154	return FIND_NTH_BIT(addr1[idx] & ~addr2[idx], size, n);
	155	}
	156	EXPORT_SYMBOL(__find_nth_andnot_bit);
	157
43245117 YN	158	unsigned long __find_nth_and_andnot_bit(const unsigned long *addr1,
	159	const unsigned long *addr2,
	160	const unsigned long *addr3,
	161	unsigned long size, unsigned long n)
	162	{
	163	return FIND_NTH_BIT(addr1[idx] & addr2[idx] & ~addr3[idx], size, n);
	164	}
	165	EXPORT_SYMBOL(__find_nth_and_andnot_bit);
	166
e79864f3 YN	167	#ifndef find_next_and_bit
	168	unsigned long _find_next_and_bit(const unsigned long addr1, const unsigned long addr2,
	169	unsigned long nbits, unsigned long start)
	170	{
	171	return FIND_NEXT_BIT(addr1[idx] & addr2[idx], /* nop */, nbits, start);
	172	}
	173	EXPORT_SYMBOL(_find_next_and_bit);
	174	#endif
	175
90d48290 VS	176	#ifndef find_next_andnot_bit
	177	unsigned long _find_next_andnot_bit(const unsigned long addr1, const unsigned long addr2,
	178	unsigned long nbits, unsigned long start)
	179	{
	180	return FIND_NEXT_BIT(addr1[idx] & ~addr2[idx], /* nop */, nbits, start);
	181	}
	182	EXPORT_SYMBOL(_find_next_andnot_bit);
	183	#endif
	184
1470afef DC	185	#ifndef find_next_or_bit
	186	unsigned long _find_next_or_bit(const unsigned long addr1, const unsigned long addr2,
	187	unsigned long nbits, unsigned long start)
	188	{
	189	return FIND_NEXT_BIT(addr1[idx] \| addr2[idx], /* nop */, nbits, start);
	190	}
	191	EXPORT_SYMBOL(_find_next_or_bit);
	192	#endif
	193
e79864f3 YN	194	#ifndef find_next_zero_bit
	195	unsigned long _find_next_zero_bit(const unsigned long *addr, unsigned long nbits,
	196	unsigned long start)
	197	{
	198	return FIND_NEXT_BIT(~addr[idx], /* nop */, nbits, start);
	199	}
	200	EXPORT_SYMBOL(_find_next_zero_bit);
	201	#endif
	202
8f6f19dd	203	#ifndef find_last_bit
2cc7b6a4	204	unsigned long _find_last_bit(const unsigned long *addr, unsigned long size)
8f6f19dd YN	205	{
	206	if (size) {
	207	unsigned long val = BITMAP_LAST_WORD_MASK(size);
	208	unsigned long idx = (size-1) / BITS_PER_LONG;
	209
	210	do {
	211	val &= addr[idx];
	212	if (val)
	213	return idx * BITS_PER_LONG + __fls(val);
	214
	215	val = ~0ul;
	216	} while (idx--);
	217	}
	218	return size;
	219	}
2cc7b6a4	220	EXPORT_SYMBOL(_find_last_bit);
8f6f19dd YN	221	#endif
8f6f19dd YN	222
169c474f WBG	223	unsigned long find_next_clump8(unsigned long clump, const unsigned long addr,
	224	unsigned long size, unsigned long offset)
	225	{
	226	offset = find_next_bit(addr, size, offset);
	227	if (offset == size)
	228	return size;
	229
	230	offset = round_down(offset, 8);
	231	*clump = bitmap_get_value8(addr, offset);
	232
	233	return offset;
	234	}
	235	EXPORT_SYMBOL(find_next_clump8);
14a99e13 YN	236
	237	#ifdef __BIG_ENDIAN
	238
	239	#ifndef find_first_zero_bit_le
	240	/*
	241	* Find the first cleared bit in an LE memory region.
	242	*/
	243	unsigned long _find_first_zero_bit_le(const unsigned long *addr, unsigned long size)
	244	{
	245	return FIND_FIRST_BIT(~addr[idx], swab, size);
	246	}
	247	EXPORT_SYMBOL(_find_first_zero_bit_le);
	248
	249	#endif
	250
e79864f3 YN	251	#ifndef find_next_zero_bit_le
	252	unsigned long _find_next_zero_bit_le(const unsigned long *addr,
	253	unsigned long size, unsigned long offset)
	254	{
	255	return FIND_NEXT_BIT(~addr[idx], swab, size, offset);
	256	}
	257	EXPORT_SYMBOL(_find_next_zero_bit_le);
	258	#endif
	259
	260	#ifndef find_next_bit_le
	261	unsigned long _find_next_bit_le(const unsigned long *addr,
	262	unsigned long size, unsigned long offset)
	263	{
	264	return FIND_NEXT_BIT(addr[idx], swab, size, offset);
	265	}
	266	EXPORT_SYMBOL(_find_next_bit_le);
	267
	268	#endif
	269
14a99e13	270	#endif /* __BIG_ENDIAN */