276 lines
6.4 KiB
C
276 lines
6.4 KiB
C
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/* find_next_bit.c: fallback find next bit implementation
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*
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* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/bitops.h>
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#include <linux/module.h>
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#include <asm/types.h>
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#include <asm/byteorder.h>
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#define BITOP_WORD(nr) ((nr) / BITS_PER_LONG)
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#ifdef CONFIG_GENERIC_FIND_NEXT_BIT
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/*
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* Find the next set bit in a memory region.
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*/
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unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
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unsigned long offset)
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{
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const unsigned long *p = addr + BITOP_WORD(offset);
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unsigned long result = offset & ~(BITS_PER_LONG-1);
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unsigned long tmp;
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if (offset >= size)
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return size;
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size -= result;
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offset %= BITS_PER_LONG;
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if (offset) {
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tmp = *(p++);
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tmp &= (~0UL << offset);
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if (size < BITS_PER_LONG)
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goto found_first;
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if (tmp)
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goto found_middle;
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size -= BITS_PER_LONG;
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result += BITS_PER_LONG;
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}
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while (size & ~(BITS_PER_LONG-1)) {
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if ((tmp = *(p++)))
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goto found_middle;
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result += BITS_PER_LONG;
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size -= BITS_PER_LONG;
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}
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if (!size)
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return result;
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tmp = *p;
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found_first:
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tmp &= (~0UL >> (BITS_PER_LONG - size));
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if (tmp == 0UL) /* Are any bits set? */
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return result + size; /* Nope. */
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found_middle:
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return result + __ffs(tmp);
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}
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EXPORT_SYMBOL(find_next_bit);
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/*
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* This implementation of find_{first,next}_zero_bit was stolen from
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* Linus' asm-alpha/bitops.h.
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*/
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unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
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unsigned long offset)
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{
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const unsigned long *p = addr + BITOP_WORD(offset);
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unsigned long result = offset & ~(BITS_PER_LONG-1);
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unsigned long tmp;
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if (offset >= size)
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return size;
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size -= result;
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offset %= BITS_PER_LONG;
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if (offset) {
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tmp = *(p++);
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tmp |= ~0UL >> (BITS_PER_LONG - offset);
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if (size < BITS_PER_LONG)
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goto found_first;
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if (~tmp)
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goto found_middle;
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size -= BITS_PER_LONG;
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result += BITS_PER_LONG;
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}
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while (size & ~(BITS_PER_LONG-1)) {
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if (~(tmp = *(p++)))
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goto found_middle;
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result += BITS_PER_LONG;
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size -= BITS_PER_LONG;
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}
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if (!size)
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return result;
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tmp = *p;
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found_first:
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tmp |= ~0UL << size;
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if (tmp == ~0UL) /* Are any bits zero? */
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return result + size; /* Nope. */
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found_middle:
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return result + ffz(tmp);
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}
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EXPORT_SYMBOL(find_next_zero_bit);
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#endif /* CONFIG_GENERIC_FIND_NEXT_BIT */
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#ifdef CONFIG_GENERIC_FIND_FIRST_BIT
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/*
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* Find the first set bit in a memory region.
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*/
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unsigned long find_first_bit(const unsigned long *addr, unsigned long size)
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{
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const unsigned long *p = addr;
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unsigned long result = 0;
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unsigned long tmp;
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while (size & ~(BITS_PER_LONG-1)) {
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if ((tmp = *(p++)))
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goto found;
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result += BITS_PER_LONG;
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size -= BITS_PER_LONG;
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}
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if (!size)
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return result;
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tmp = (*p) & (~0UL >> (BITS_PER_LONG - size));
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if (tmp == 0UL) /* Are any bits set? */
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return result + size; /* Nope. */
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found:
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return result + __ffs(tmp);
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}
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EXPORT_SYMBOL(find_first_bit);
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/*
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* Find the first cleared bit in a memory region.
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*/
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unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size)
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{
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const unsigned long *p = addr;
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unsigned long result = 0;
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unsigned long tmp;
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while (size & ~(BITS_PER_LONG-1)) {
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if (~(tmp = *(p++)))
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goto found;
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result += BITS_PER_LONG;
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size -= BITS_PER_LONG;
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}
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if (!size)
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return result;
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tmp = (*p) | (~0UL << size);
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if (tmp == ~0UL) /* Are any bits zero? */
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return result + size; /* Nope. */
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found:
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return result + ffz(tmp);
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}
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EXPORT_SYMBOL(find_first_zero_bit);
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#endif /* CONFIG_GENERIC_FIND_FIRST_BIT */
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#ifdef __BIG_ENDIAN
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/* include/linux/byteorder does not support "unsigned long" type */
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static inline unsigned long ext2_swabp(const unsigned long * x)
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{
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#if BITS_PER_LONG == 64
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return (unsigned long) __swab64p((u64 *) x);
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#elif BITS_PER_LONG == 32
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return (unsigned long) __swab32p((u32 *) x);
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#else
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#error BITS_PER_LONG not defined
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#endif
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}
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/* include/linux/byteorder doesn't support "unsigned long" type */
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static inline unsigned long ext2_swab(const unsigned long y)
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{
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#if BITS_PER_LONG == 64
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return (unsigned long) __swab64((u64) y);
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#elif BITS_PER_LONG == 32
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return (unsigned long) __swab32((u32) y);
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#else
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#error BITS_PER_LONG not defined
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#endif
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}
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unsigned long generic_find_next_zero_le_bit(const unsigned long *addr, unsigned
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long size, unsigned long offset)
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{
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const unsigned long *p = addr + BITOP_WORD(offset);
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unsigned long result = offset & ~(BITS_PER_LONG - 1);
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unsigned long tmp;
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if (offset >= size)
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return size;
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size -= result;
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offset &= (BITS_PER_LONG - 1UL);
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if (offset) {
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tmp = ext2_swabp(p++);
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tmp |= (~0UL >> (BITS_PER_LONG - offset));
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if (size < BITS_PER_LONG)
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goto found_first;
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if (~tmp)
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goto found_middle;
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size -= BITS_PER_LONG;
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result += BITS_PER_LONG;
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}
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while (size & ~(BITS_PER_LONG - 1)) {
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if (~(tmp = *(p++)))
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goto found_middle_swap;
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result += BITS_PER_LONG;
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size -= BITS_PER_LONG;
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}
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if (!size)
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return result;
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tmp = ext2_swabp(p);
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found_first:
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tmp |= ~0UL << size;
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if (tmp == ~0UL) /* Are any bits zero? */
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return result + size; /* Nope. Skip ffz */
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found_middle:
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return result + ffz(tmp);
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found_middle_swap:
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return result + ffz(ext2_swab(tmp));
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}
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EXPORT_SYMBOL(generic_find_next_zero_le_bit);
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unsigned long generic_find_next_le_bit(const unsigned long *addr, unsigned
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long size, unsigned long offset)
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{
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const unsigned long *p = addr + BITOP_WORD(offset);
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unsigned long result = offset & ~(BITS_PER_LONG - 1);
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unsigned long tmp;
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if (offset >= size)
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return size;
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size -= result;
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offset &= (BITS_PER_LONG - 1UL);
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if (offset) {
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tmp = ext2_swabp(p++);
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tmp &= (~0UL << offset);
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if (size < BITS_PER_LONG)
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goto found_first;
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if (tmp)
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goto found_middle;
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size -= BITS_PER_LONG;
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result += BITS_PER_LONG;
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}
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while (size & ~(BITS_PER_LONG - 1)) {
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tmp = *(p++);
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if (tmp)
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goto found_middle_swap;
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result += BITS_PER_LONG;
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size -= BITS_PER_LONG;
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}
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if (!size)
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return result;
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tmp = ext2_swabp(p);
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found_first:
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tmp &= (~0UL >> (BITS_PER_LONG - size));
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if (tmp == 0UL) /* Are any bits set? */
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return result + size; /* Nope. */
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found_middle:
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return result + __ffs(tmp);
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found_middle_swap:
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return result + __ffs(ext2_swab(tmp));
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}
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EXPORT_SYMBOL(generic_find_next_le_bit);
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#endif /* __BIG_ENDIAN */
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