[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)

/**
 * find_next_bit - find the next set bit in a memory region
 * @addr: The address to base the search on
 * @offset: The bitnumber to start searching at
 * @size: The maximum size to search
 */
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);

/*
 * 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);

#ifdef __BIG_ENDIAN

/* 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
}

unsigned long generic_find_next_zero_le_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 - 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(generic_find_next_zero_le_bit);

#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)
	18
	19	/**
	20	* find_next_bit - find the next set bit in a memory region
	21	* @addr: The address to base the search on
	22	* @offset: The bitnumber to start searching at
	23	* @size: The maximum size to search
	24	*/
	25	unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
	26	unsigned long offset)
1da177e4	27	{
c7f612cd AM	28	const unsigned long *p = addr + BITOP_WORD(offset);
c7f612cd AM	29	unsigned long result = offset & ~(BITS_PER_LONG-1);
1da177e4 LT	30	unsigned long tmp;
1da177e4 LT	31
c7f612cd AM	32	if (offset >= size)
	33	return size;
	34	size -= result;
	35	offset %= BITS_PER_LONG;
1da177e4	36	if (offset) {
c7f612cd AM	37	tmp = *(p++);
	38	tmp &= (~0UL << offset);
	39	if (size < BITS_PER_LONG)
	40	goto found_first;
	41	if (tmp)
	42	goto found_middle;
	43	size -= BITS_PER_LONG;
	44	result += BITS_PER_LONG;
	45	}
	46	while (size & ~(BITS_PER_LONG-1)) {
	47	if ((tmp = *(p++)))
	48	goto found_middle;
	49	result += BITS_PER_LONG;
	50	size -= BITS_PER_LONG;
1da177e4	51	}
c7f612cd AM	52	if (!size)
	53	return result;
	54	tmp = *p;
1da177e4	55
c7f612cd AM	56	found_first:
	57	tmp &= (~0UL >> (BITS_PER_LONG - size));
	58	if (tmp == 0UL) /* Are any bits set? */
	59	return result + size; /* Nope. */
	60	found_middle:
	61	return result + __ffs(tmp);
	62	}
1da177e4	63
c7f612cd	64	EXPORT_SYMBOL(find_next_bit);
1da177e4	65
c7f612cd AM	66	/*
	67	* This implementation of find_{first,next}_zero_bit was stolen from
	68	* Linus' asm-alpha/bitops.h.
	69	*/
	70	unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
	71	unsigned long offset)
	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	}
40234401	108
c7f612cd	109	EXPORT_SYMBOL(find_next_zero_bit);
930ae745 AM	110
	111	#ifdef __BIG_ENDIAN
	112
	113	/* include/linux/byteorder does not support "unsigned long" type */
	114	static inline unsigned long ext2_swabp(const unsigned long * x)
	115	{
	116	#if BITS_PER_LONG == 64
	117	return (unsigned long) __swab64p((u64 *) x);
	118	#elif BITS_PER_LONG == 32
	119	return (unsigned long) __swab32p((u32 *) x);
	120	#else
	121	#error BITS_PER_LONG not defined
	122	#endif
	123	}
	124
	125	/* include/linux/byteorder doesn't support "unsigned long" type */
	126	static inline unsigned long ext2_swab(const unsigned long y)
	127	{
	128	#if BITS_PER_LONG == 64
	129	return (unsigned long) __swab64((u64) y);
	130	#elif BITS_PER_LONG == 32
	131	return (unsigned long) __swab32((u32) y);
	132	#else
	133	#error BITS_PER_LONG not defined
	134	#endif
	135	}
	136
	137	unsigned long generic_find_next_zero_le_bit(const unsigned long *addr, unsigned
	138	long size, unsigned long offset)
	139	{
	140	const unsigned long *p = addr + BITOP_WORD(offset);
	141	unsigned long result = offset & ~(BITS_PER_LONG - 1);
	142	unsigned long tmp;
	143
	144	if (offset >= size)
	145	return size;
	146	size -= result;
	147	offset &= (BITS_PER_LONG - 1UL);
	148	if (offset) {
	149	tmp = ext2_swabp(p++);
	150	tmp \|= (~0UL >> (BITS_PER_LONG - offset));
	151	if (size < BITS_PER_LONG)
	152	goto found_first;
	153	if (~tmp)
	154	goto found_middle;
	155	size -= BITS_PER_LONG;
	156	result += BITS_PER_LONG;
	157	}
	158
	159	while (size & ~(BITS_PER_LONG - 1)) {
	160	if (~(tmp = *(p++)))
	161	goto found_middle_swap;
	162	result += BITS_PER_LONG;
	163	size -= BITS_PER_LONG;
	164	}
	165	if (!size)
	166	return result;
	167	tmp = ext2_swabp(p);
	168	found_first:
	169	tmp \|= ~0UL << size;
	170	if (tmp == ~0UL) /* Are any bits zero? */
	171	return result + size; /* Nope. Skip ffz */
	172	found_middle:
	173	return result + ffz(tmp);
174
175	found_middle_swap:
176	return result + ffz(ext2_swab(tmp));
177	}
178
179	EXPORT_SYMBOL(generic_find_next_zero_le_bit);
180
181	#endif /* __BIG_ENDIAN */