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

/* find_next_bit.c: fallback find next bit implementation
 *
 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * 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/module.h>
#include <asm/types.h>
#include <asm/byteorder.h>

#define BITOP_WORD(nr)		((nr) / BITS_PER_LONG)

#ifdef CONFIG_GENERIC_FIND_NEXT_BIT
#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)
{
	const unsigned long *p = addr + BITOP_WORD(offset);
	unsigned long result = offset & ~(BITS_PER_LONG-1);
	unsigned long tmp;

	if (offset >= size)
		return size;
	size -= result;
	offset %= BITS_PER_LONG;
	if (offset) {
		tmp = *(p++);
		tmp &= (~0UL << offset);
		if (size < BITS_PER_LONG)
			goto found_first;
		if (tmp)
			goto found_middle;
		size -= BITS_PER_LONG;
		result += BITS_PER_LONG;
	}
	while (size & ~(BITS_PER_LONG-1)) {
		if ((tmp = *(p++)))
			goto found_middle;
		result += BITS_PER_LONG;
		size -= BITS_PER_LONG;
	}
	if (!size)
		return result;
	tmp = *p;

found_first:
	tmp &= (~0UL >> (BITS_PER_LONG - size));
	if (tmp == 0UL)		/* Are any bits set? */
		return result + size;	/* Nope. */
found_middle:
	return result + __ffs(tmp);
}
EXPORT_SYMBOL(find_next_bit);
#endif

#ifndef find_next_zero_bit
/*
 * This implementation of find_{first,next}_zero_bit was stolen from
 * Linus' asm-alpha/bitops.h.
 */
unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
				 unsigned long offset)
{
	const unsigned long *p = addr + BITOP_WORD(offset);
	unsigned long result = offset & ~(BITS_PER_LONG-1);
	unsigned long tmp;

	if (offset >= size)
		return size;
	size -= result;
	offset %= BITS_PER_LONG;
	if (offset) {
		tmp = *(p++);
		tmp |= ~0UL >> (BITS_PER_LONG - offset);
		if (size < BITS_PER_LONG)
			goto found_first;
		if (~tmp)
			goto found_middle;
		size -= BITS_PER_LONG;
		result += BITS_PER_LONG;
	}
	while (size & ~(BITS_PER_LONG-1)) {
		if (~(tmp = *(p++)))
			goto found_middle;
		result += BITS_PER_LONG;
		size -= BITS_PER_LONG;
	}
	if (!size)
		return result;
	tmp = *p;

found_first:
	tmp |= ~0UL << size;
	if (tmp == ~0UL)	/* Are any bits zero? */
		return result + size;	/* Nope. */
found_middle:
	return result + ffz(tmp);
}
EXPORT_SYMBOL(find_next_zero_bit);
#endif
#endif /* CONFIG_GENERIC_FIND_NEXT_BIT */

#ifdef CONFIG_GENERIC_FIND_FIRST_BIT
#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)
{
	const unsigned long *p = addr;
	unsigned long result = 0;
	unsigned long tmp;

	while (size & ~(BITS_PER_LONG-1)) {
		if ((tmp = *(p++)))
			goto found;
		result += BITS_PER_LONG;
		size -= BITS_PER_LONG;
	}
	if (!size)
		return result;

	tmp = (*p) & (~0UL >> (BITS_PER_LONG - size));
	if (tmp == 0UL)		/* Are any bits set? */
		return result + size;	/* Nope. */
found:
	return result + __ffs(tmp);
}
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)
{
	const unsigned long *p = addr;
	unsigned long result = 0;
	unsigned long tmp;

	while (size & ~(BITS_PER_LONG-1)) {
		if (~(tmp = *(p++)))
			goto found;
		result += BITS_PER_LONG;
		size -= BITS_PER_LONG;
	}
	if (!size)
		return result;

	tmp = (*p) | (~0UL << size);
	if (tmp == ~0UL)	/* Are any bits zero? */
		return result + size;	/* Nope. */
found:
	return result + ffz(tmp);
}
EXPORT_SYMBOL(find_first_zero_bit);
#endif
#endif /* CONFIG_GENERIC_FIND_FIRST_BIT */

#ifdef __BIG_ENDIAN
#ifdef CONFIG_GENERIC_FIND_BIT_LE

/* include/linux/byteorder does not support "unsigned long" type */
static inline unsigned long ext2_swabp(const unsigned long * x)
{
#if BITS_PER_LONG == 64
	return (unsigned long) __swab64p((u64 *) x);
#elif BITS_PER_LONG == 32
	return (unsigned long) __swab32p((u32 *) x);
#else
#error BITS_PER_LONG not defined
#endif
}

/* include/linux/byteorder doesn't 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
}

#ifndef find_next_zero_bit_le
unsigned long find_next_zero_bit_le(const void *addr, unsigned
		long size, unsigned long offset)
{
	const unsigned long *p = addr;
	unsigned long result = offset & ~(BITS_PER_LONG - 1);
	unsigned long tmp;

	if (offset >= size)
		return size;
	p += BITOP_WORD(offset);
	size -= result;
	offset &= (BITS_PER_LONG - 1UL);
	if (offset) {
		tmp = ext2_swabp(p++);
		tmp |= (~0UL >> (BITS_PER_LONG - offset));
		if (size < BITS_PER_LONG)
			goto found_first;
		if (~tmp)
			goto found_middle;
		size -= BITS_PER_LONG;
		result += BITS_PER_LONG;
	}

	while (size & ~(BITS_PER_LONG - 1)) {
		if (~(tmp = *(p++)))
			goto found_middle_swap;
		result += BITS_PER_LONG;
		size -= BITS_PER_LONG;
	}
	if (!size)
		return result;
	tmp = ext2_swabp(p);
found_first:
	tmp |= ~0UL << size;
	if (tmp == ~0UL)	/* Are any bits zero? */
		return result + size; /* Nope. Skip ffz */
found_middle:
	return result + ffz(tmp);

found_middle_swap:
	return result + ffz(ext2_swab(tmp));
}
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)
{
	const unsigned long *p = addr;
	unsigned long result = offset & ~(BITS_PER_LONG - 1);
	unsigned long tmp;

	if (offset >= size)
		return size;
	p += BITOP_WORD(offset);
	size -= result;
	offset &= (BITS_PER_LONG - 1UL);
	if (offset) {
		tmp = ext2_swabp(p++);
		tmp &= (~0UL << offset);
		if (size < BITS_PER_LONG)
			goto found_first;
		if (tmp)
			goto found_middle;
		size -= BITS_PER_LONG;
		result += BITS_PER_LONG;
	}

	while (size & ~(BITS_PER_LONG - 1)) {
		tmp = *(p++);
		if (tmp)
			goto found_middle_swap;
		result += BITS_PER_LONG;
		size -= BITS_PER_LONG;
	}
	if (!size)
		return result;
	tmp = ext2_swabp(p);
found_first:
	tmp &= (~0UL >> (BITS_PER_LONG - size));
	if (tmp == 0UL)		/* Are any bits set? */
		return result + size; /* Nope. */
found_middle:
	return result + __ffs(tmp);

found_middle_swap:
	return result + __ffs(ext2_swab(tmp));
}
EXPORT_SYMBOL(find_next_bit_le);
#endif

#endif /* CONFIG_GENERIC_FIND_BIT_LE */
#endif /* __BIG_ENDIAN */
Commit	Line	Data
1da177e4 LT	1	/* find_next_bit.c: fallback find next bit implementation
	2	*
	3	* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
	4	* Written by David Howells (dhowells@redhat.com)
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public License
	8	* as published by the Free Software Foundation; either version
	9	* 2 of the License, or (at your option) any later version.
	10	*/
	11
	12	#include <linux/bitops.h>
40234401	13	#include <linux/module.h>
c7f612cd	14	#include <asm/types.h>
930ae745	15	#include <asm/byteorder.h>
1da177e4	16
c7f612cd AM	17	#define BITOP_WORD(nr) ((nr) / BITS_PER_LONG)
c7f612cd AM	18
77b9bd9c	19	#ifdef CONFIG_GENERIC_FIND_NEXT_BIT
19de85ef	20	#ifndef find_next_bit
64970b68 AH	21	/*
64970b68 AH	22	* Find the next set bit in a memory region.
c7f612cd	23	*/
fee4b19f TG	24	unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
fee4b19f TG	25	unsigned long offset)
1da177e4	26	{
c7f612cd AM	27	const unsigned long *p = addr + BITOP_WORD(offset);
c7f612cd AM	28	unsigned long result = offset & ~(BITS_PER_LONG-1);
1da177e4 LT	29	unsigned long tmp;
1da177e4 LT	30
c7f612cd AM	31	if (offset >= size)
	32	return size;
	33	size -= result;
	34	offset %= BITS_PER_LONG;
1da177e4	35	if (offset) {
c7f612cd AM	36	tmp = *(p++);
	37	tmp &= (~0UL << offset);
	38	if (size < BITS_PER_LONG)
	39	goto found_first;
	40	if (tmp)
	41	goto found_middle;
	42	size -= BITS_PER_LONG;
	43	result += BITS_PER_LONG;
	44	}
	45	while (size & ~(BITS_PER_LONG-1)) {
	46	if ((tmp = *(p++)))
	47	goto found_middle;
	48	result += BITS_PER_LONG;
	49	size -= BITS_PER_LONG;
1da177e4	50	}
c7f612cd AM	51	if (!size)
	52	return result;
	53	tmp = *p;
1da177e4	54
c7f612cd AM	55	found_first:
	56	tmp &= (~0UL >> (BITS_PER_LONG - size));
	57	if (tmp == 0UL) /* Are any bits set? */
	58	return result + size; /* Nope. */
	59	found_middle:
	60	return result + __ffs(tmp);
	61	}
fee4b19f	62	EXPORT_SYMBOL(find_next_bit);
19de85ef	63	#endif
1da177e4	64
19de85ef	65	#ifndef find_next_zero_bit
c7f612cd AM	66	/*
	67	* This implementation of find_{first,next}_zero_bit was stolen from
	68	* Linus' asm-alpha/bitops.h.
	69	*/
fee4b19f TG	70	unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
fee4b19f TG	71	unsigned long offset)
c7f612cd AM	72	{
	73	const unsigned long *p = addr + BITOP_WORD(offset);
	74	unsigned long result = offset & ~(BITS_PER_LONG-1);
	75	unsigned long tmp;
1da177e4	76
c7f612cd AM	77	if (offset >= size)
	78	return size;
	79	size -= result;
	80	offset %= BITS_PER_LONG;
	81	if (offset) {
	82	tmp = *(p++);
	83	tmp \|= ~0UL >> (BITS_PER_LONG - offset);
	84	if (size < BITS_PER_LONG)
	85	goto found_first;
	86	if (~tmp)
	87	goto found_middle;
	88	size -= BITS_PER_LONG;
	89	result += BITS_PER_LONG;
	90	}
	91	while (size & ~(BITS_PER_LONG-1)) {
	92	if (~(tmp = *(p++)))
	93	goto found_middle;
	94	result += BITS_PER_LONG;
	95	size -= BITS_PER_LONG;
1da177e4	96	}
c7f612cd AM	97	if (!size)
	98	return result;
	99	tmp = *p;
1da177e4	100
c7f612cd AM	101	found_first:
	102	tmp \|= ~0UL << size;
	103	if (tmp == ~0UL) /* Are any bits zero? */
	104	return result + size; /* Nope. */
	105	found_middle:
	106	return result + ffz(tmp);
1da177e4	107	}
fee4b19f	108	EXPORT_SYMBOL(find_next_zero_bit);
19de85ef	109	#endif
77b9bd9c AH	110	#endif /* CONFIG_GENERIC_FIND_NEXT_BIT */
	111
	112	#ifdef CONFIG_GENERIC_FIND_FIRST_BIT
19de85ef	113	#ifndef find_first_bit
77b9bd9c AH	114	/*
	115	* Find the first set bit in a memory region.
	116	*/
fee4b19f	117	unsigned long find_first_bit(const unsigned long *addr, unsigned long size)
77b9bd9c AH	118	{
	119	const unsigned long *p = addr;
	120	unsigned long result = 0;
	121	unsigned long tmp;
	122
	123	while (size & ~(BITS_PER_LONG-1)) {
	124	if ((tmp = *(p++)))
	125	goto found;
	126	result += BITS_PER_LONG;
	127	size -= BITS_PER_LONG;
	128	}
	129	if (!size)
	130	return result;
	131
	132	tmp = (*p) & (~0UL >> (BITS_PER_LONG - size));
	133	if (tmp == 0UL) /* Are any bits set? */
	134	return result + size; /* Nope. */
	135	found:
	136	return result + __ffs(tmp);
	137	}
fee4b19f	138	EXPORT_SYMBOL(find_first_bit);
19de85ef	139	#endif
77b9bd9c	140
19de85ef	141	#ifndef find_first_zero_bit
77b9bd9c AH	142	/*
	143	* Find the first cleared bit in a memory region.
	144	*/
fee4b19f	145	unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size)
77b9bd9c AH	146	{
	147	const unsigned long *p = addr;
	148	unsigned long result = 0;
	149	unsigned long tmp;
	150
	151	while (size & ~(BITS_PER_LONG-1)) {
	152	if (~(tmp = *(p++)))
	153	goto found;
	154	result += BITS_PER_LONG;
	155	size -= BITS_PER_LONG;
	156	}
	157	if (!size)
	158	return result;
	159
	160	tmp = (*p) \| (~0UL << size);
	161	if (tmp == ~0UL) /* Are any bits zero? */
	162	return result + size; /* Nope. */
	163	found:
	164	return result + ffz(tmp);
	165	}
fee4b19f	166	EXPORT_SYMBOL(find_first_zero_bit);
19de85ef	167	#endif
77b9bd9c	168	#endif /* CONFIG_GENERIC_FIND_FIRST_BIT */
930ae745 AM	169
930ae745 AM	170	#ifdef __BIG_ENDIAN
0664996b	171	#ifdef CONFIG_GENERIC_FIND_BIT_LE
930ae745 AM	172
	173	/* include/linux/byteorder does not support "unsigned long" type */
	174	static inline unsigned long ext2_swabp(const unsigned long * x)
	175	{
	176	#if BITS_PER_LONG == 64
	177	return (unsigned long) __swab64p((u64 *) x);
	178	#elif BITS_PER_LONG == 32
	179	return (unsigned long) __swab32p((u32 *) x);
	180	#else
	181	#error BITS_PER_LONG not defined
	182	#endif
	183	}
	184
	185	/* include/linux/byteorder doesn't support "unsigned long" type */
	186	static inline unsigned long ext2_swab(const unsigned long y)
	187	{
	188	#if BITS_PER_LONG == 64
	189	return (unsigned long) __swab64((u64) y);
	190	#elif BITS_PER_LONG == 32
	191	return (unsigned long) __swab32((u32) y);
	192	#else
	193	#error BITS_PER_LONG not defined
	194	#endif
	195	}
	196
19de85ef	197	#ifndef find_next_zero_bit_le
a56560b3	198	unsigned long find_next_zero_bit_le(const void *addr, unsigned
930ae745 AM	199	long size, unsigned long offset)
930ae745 AM	200	{
a56560b3	201	const unsigned long *p = addr;
930ae745 AM	202	unsigned long result = offset & ~(BITS_PER_LONG - 1);
	203	unsigned long tmp;
	204
	205	if (offset >= size)
	206	return size;
a56560b3	207	p += BITOP_WORD(offset);
930ae745 AM	208	size -= result;
	209	offset &= (BITS_PER_LONG - 1UL);
	210	if (offset) {
	211	tmp = ext2_swabp(p++);
	212	tmp \|= (~0UL >> (BITS_PER_LONG - offset));
	213	if (size < BITS_PER_LONG)
	214	goto found_first;
	215	if (~tmp)
	216	goto found_middle;
	217	size -= BITS_PER_LONG;
	218	result += BITS_PER_LONG;
	219	}
	220
	221	while (size & ~(BITS_PER_LONG - 1)) {
	222	if (~(tmp = *(p++)))
	223	goto found_middle_swap;
	224	result += BITS_PER_LONG;
	225	size -= BITS_PER_LONG;
	226	}
	227	if (!size)
	228	return result;
	229	tmp = ext2_swabp(p);
	230	found_first:
	231	tmp \|= ~0UL << size;
	232	if (tmp == ~0UL) /* Are any bits zero? */
	233	return result + size; /* Nope. Skip ffz */
	234	found_middle:
	235	return result + ffz(tmp);
	236
	237	found_middle_swap:
	238	return result + ffz(ext2_swab(tmp));
	239	}
c4945b9e	240	EXPORT_SYMBOL(find_next_zero_bit_le);
19de85ef	241	#endif
930ae745	242
19de85ef	243	#ifndef find_next_bit_le
a56560b3	244	unsigned long find_next_bit_le(const void *addr, unsigned
aa02ad67 AK	245	long size, unsigned long offset)
aa02ad67 AK	246	{
a56560b3	247	const unsigned long *p = addr;
aa02ad67 AK	248	unsigned long result = offset & ~(BITS_PER_LONG - 1);
	249	unsigned long tmp;
	250
	251	if (offset >= size)
	252	return size;
a56560b3	253	p += BITOP_WORD(offset);
aa02ad67 AK	254	size -= result;
	255	offset &= (BITS_PER_LONG - 1UL);
	256	if (offset) {
	257	tmp = ext2_swabp(p++);
	258	tmp &= (~0UL << offset);
	259	if (size < BITS_PER_LONG)
	260	goto found_first;
	261	if (tmp)
	262	goto found_middle;
	263	size -= BITS_PER_LONG;
	264	result += BITS_PER_LONG;
	265	}
	266
	267	while (size & ~(BITS_PER_LONG - 1)) {
	268	tmp = *(p++);
	269	if (tmp)
	270	goto found_middle_swap;
	271	result += BITS_PER_LONG;
	272	size -= BITS_PER_LONG;
	273	}
	274	if (!size)
	275	return result;
	276	tmp = ext2_swabp(p);
	277	found_first:
	278	tmp &= (~0UL >> (BITS_PER_LONG - size));
	279	if (tmp == 0UL) /* Are any bits set? */
	280	return result + size; /* Nope. */
	281	found_middle:
	282	return result + __ffs(tmp);
	283
	284	found_middle_swap:
	285	return result + __ffs(ext2_swab(tmp));
	286	}
c4945b9e	287	EXPORT_SYMBOL(find_next_bit_le);
19de85ef	288	#endif
0664996b AM	289
0664996b AM	290	#endif /* CONFIG_GENERIC_FIND_BIT_LE */
930ae745	291	#endif /* __BIG_ENDIAN */