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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 5270 | serge | 1 | /* find_next_bit.c: fallback find next bit implementation |
| 2 | * |
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| 3 | * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved. |
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| 4 | * Written by David Howells (dhowells@redhat.com) |
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| 5 | * |
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| 6 | * This program is free software; you can redistribute it and/or |
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| 7 | * modify it under the terms of the GNU General Public License |
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| 8 | * as published by the Free Software Foundation; either version |
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| 9 | * 2 of the License, or (at your option) any later version. |
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| 10 | */ |
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| 11 | |||
| 12 | #include |
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| 13 | #include |
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| 14 | #include |
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| 15 | #include |
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| 16 | |||
| 17 | #define BITOP_WORD(nr) ((nr) / BITS_PER_LONG) |
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| 18 | |||
| 19 | #ifndef find_next_bit |
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| 20 | /* |
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| 21 | * Find the next set bit in a memory region. |
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| 22 | */ |
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| 23 | unsigned long find_next_bit(const unsigned long *addr, unsigned long size, |
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| 24 | unsigned long offset) |
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| 25 | { |
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| 26 | const unsigned long *p = addr + BITOP_WORD(offset); |
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| 27 | unsigned long result = offset & ~(BITS_PER_LONG-1); |
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| 28 | unsigned long tmp; |
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| 29 | |||
| 30 | if (offset >= size) |
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| 31 | return size; |
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| 32 | size -= result; |
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| 33 | offset %= BITS_PER_LONG; |
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| 34 | if (offset) { |
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| 35 | tmp = *(p++); |
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| 36 | tmp &= (~0UL << offset); |
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| 37 | if (size < BITS_PER_LONG) |
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| 38 | goto found_first; |
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| 39 | if (tmp) |
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| 40 | goto found_middle; |
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| 41 | size -= BITS_PER_LONG; |
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| 42 | result += BITS_PER_LONG; |
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| 43 | } |
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| 44 | while (size & ~(BITS_PER_LONG-1)) { |
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| 45 | if ((tmp = *(p++))) |
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| 46 | goto found_middle; |
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| 47 | result += BITS_PER_LONG; |
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| 48 | size -= BITS_PER_LONG; |
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| 49 | } |
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| 50 | if (!size) |
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| 51 | return result; |
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| 52 | tmp = *p; |
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| 53 | |||
| 54 | found_first: |
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| 55 | tmp &= (~0UL >> (BITS_PER_LONG - size)); |
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| 56 | if (tmp == 0UL) /* Are any bits set? */ |
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| 57 | return result + size; /* Nope. */ |
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| 58 | found_middle: |
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| 59 | return result + __ffs(tmp); |
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| 60 | } |
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| 61 | EXPORT_SYMBOL(find_next_bit); |
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| 62 | #endif |
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| 63 | |||
| 64 | #ifndef find_next_zero_bit |
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| 65 | /* |
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| 66 | * This implementation of find_{first,next}_zero_bit was stolen from |
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| 67 | * Linus' asm-alpha/bitops.h. |
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| 68 | */ |
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| 69 | unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size, |
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| 70 | unsigned long offset) |
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| 71 | { |
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| 72 | const unsigned long *p = addr + BITOP_WORD(offset); |
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| 73 | unsigned long result = offset & ~(BITS_PER_LONG-1); |
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| 74 | unsigned long tmp; |
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| 75 | |||
| 76 | if (offset >= size) |
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| 77 | return size; |
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| 78 | size -= result; |
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| 79 | offset %= BITS_PER_LONG; |
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| 80 | if (offset) { |
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| 81 | tmp = *(p++); |
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| 82 | tmp |= ~0UL >> (BITS_PER_LONG - offset); |
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| 83 | if (size < BITS_PER_LONG) |
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| 84 | goto found_first; |
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| 85 | if (~tmp) |
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| 86 | goto found_middle; |
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| 87 | size -= BITS_PER_LONG; |
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| 88 | result += BITS_PER_LONG; |
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| 89 | } |
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| 90 | while (size & ~(BITS_PER_LONG-1)) { |
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| 91 | if (~(tmp = *(p++))) |
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| 92 | goto found_middle; |
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| 93 | result += BITS_PER_LONG; |
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| 94 | size -= BITS_PER_LONG; |
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| 95 | } |
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| 96 | if (!size) |
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| 97 | return result; |
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| 98 | tmp = *p; |
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| 99 | |||
| 100 | found_first: |
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| 101 | tmp |= ~0UL << size; |
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| 102 | if (tmp == ~0UL) /* Are any bits zero? */ |
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| 103 | return result + size; /* Nope. */ |
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| 104 | found_middle: |
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| 105 | return result + ffz(tmp); |
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| 106 | } |
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| 107 | EXPORT_SYMBOL(find_next_zero_bit); |
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| 108 | #endif |
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| 109 | |||
| 110 | #ifndef find_first_bit |
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| 111 | /* |
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| 112 | * Find the first set bit in a memory region. |
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| 113 | */ |
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| 114 | unsigned long find_first_bit(const unsigned long *addr, unsigned long size) |
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| 115 | { |
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| 116 | const unsigned long *p = addr; |
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| 117 | unsigned long result = 0; |
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| 118 | unsigned long tmp; |
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| 119 | |||
| 120 | while (size & ~(BITS_PER_LONG-1)) { |
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| 121 | if ((tmp = *(p++))) |
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| 122 | goto found; |
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| 123 | result += BITS_PER_LONG; |
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| 124 | size -= BITS_PER_LONG; |
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| 125 | } |
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| 126 | if (!size) |
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| 127 | return result; |
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| 128 | |||
| 129 | tmp = (*p) & (~0UL >> (BITS_PER_LONG - size)); |
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| 130 | if (tmp == 0UL) /* Are any bits set? */ |
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| 131 | return result + size; /* Nope. */ |
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| 132 | found: |
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| 133 | return result + __ffs(tmp); |
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| 134 | } |
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| 135 | EXPORT_SYMBOL(find_first_bit); |
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| 136 | #endif |
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| 137 | |||
| 138 | #ifndef find_first_zero_bit |
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| 139 | /* |
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| 140 | * Find the first cleared bit in a memory region. |
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| 141 | */ |
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| 142 | unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size) |
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| 143 | { |
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| 144 | const unsigned long *p = addr; |
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| 145 | unsigned long result = 0; |
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| 146 | unsigned long tmp; |
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| 147 | |||
| 148 | while (size & ~(BITS_PER_LONG-1)) { |
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| 149 | if (~(tmp = *(p++))) |
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| 150 | goto found; |
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| 151 | result += BITS_PER_LONG; |
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| 152 | size -= BITS_PER_LONG; |
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| 153 | } |
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| 154 | if (!size) |
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| 155 | return result; |
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| 156 | |||
| 157 | tmp = (*p) | (~0UL << size); |
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| 158 | if (tmp == ~0UL) /* Are any bits zero? */ |
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| 159 | return result + size; /* Nope. */ |
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| 160 | found: |
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| 161 | return result + ffz(tmp); |
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| 162 | } |
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| 163 | EXPORT_SYMBOL(find_first_zero_bit); |
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| 164 | #endif |
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| 165 | |||
| 166 | #ifdef __BIG_ENDIAN |
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| 167 | |||
| 168 | /* include/linux/byteorder does not support "unsigned long" type */ |
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| 169 | static inline unsigned long ext2_swabp(const unsigned long * x) |
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| 170 | { |
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| 171 | #if BITS_PER_LONG == 64 |
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| 172 | return (unsigned long) __swab64p((u64 *) x); |
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| 173 | #elif BITS_PER_LONG == 32 |
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| 174 | return (unsigned long) __swab32p((u32 *) x); |
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| 175 | #else |
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| 176 | #error BITS_PER_LONG not defined |
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| 177 | #endif |
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| 178 | } |
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| 179 | |||
| 180 | /* include/linux/byteorder doesn't support "unsigned long" type */ |
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| 181 | static inline unsigned long ext2_swab(const unsigned long y) |
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| 182 | { |
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| 183 | #if BITS_PER_LONG == 64 |
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| 184 | return (unsigned long) __swab64((u64) y); |
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| 185 | #elif BITS_PER_LONG == 32 |
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| 186 | return (unsigned long) __swab32((u32) y); |
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| 187 | #else |
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| 188 | #error BITS_PER_LONG not defined |
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| 189 | #endif |
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| 190 | } |
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| 191 | |||
| 192 | #ifndef find_next_zero_bit_le |
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| 193 | unsigned long find_next_zero_bit_le(const void *addr, unsigned |
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| 194 | long size, unsigned long offset) |
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| 195 | { |
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| 196 | const unsigned long *p = addr; |
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| 197 | unsigned long result = offset & ~(BITS_PER_LONG - 1); |
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| 198 | unsigned long tmp; |
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| 199 | |||
| 200 | if (offset >= size) |
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| 201 | return size; |
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| 202 | p += BITOP_WORD(offset); |
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| 203 | size -= result; |
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| 204 | offset &= (BITS_PER_LONG - 1UL); |
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| 205 | if (offset) { |
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| 206 | tmp = ext2_swabp(p++); |
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| 207 | tmp |= (~0UL >> (BITS_PER_LONG - offset)); |
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| 208 | if (size < BITS_PER_LONG) |
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| 209 | goto found_first; |
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| 210 | if (~tmp) |
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| 211 | goto found_middle; |
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| 212 | size -= BITS_PER_LONG; |
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| 213 | result += BITS_PER_LONG; |
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| 214 | } |
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| 215 | |||
| 216 | while (size & ~(BITS_PER_LONG - 1)) { |
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| 217 | if (~(tmp = *(p++))) |
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| 218 | goto found_middle_swap; |
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| 219 | result += BITS_PER_LONG; |
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| 220 | size -= BITS_PER_LONG; |
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| 221 | } |
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| 222 | if (!size) |
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| 223 | return result; |
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| 224 | tmp = ext2_swabp(p); |
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| 225 | found_first: |
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| 226 | tmp |= ~0UL << size; |
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| 227 | if (tmp == ~0UL) /* Are any bits zero? */ |
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| 228 | return result + size; /* Nope. Skip ffz */ |
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| 229 | found_middle: |
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| 230 | return result + ffz(tmp); |
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| 231 | |||
| 232 | found_middle_swap: |
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| 233 | return result + ffz(ext2_swab(tmp)); |
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| 234 | } |
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| 235 | EXPORT_SYMBOL(find_next_zero_bit_le); |
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| 236 | #endif |
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| 237 | |||
| 238 | #ifndef find_next_bit_le |
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| 239 | unsigned long find_next_bit_le(const void *addr, unsigned |
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| 240 | long size, unsigned long offset) |
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| 241 | { |
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| 242 | const unsigned long *p = addr; |
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| 243 | unsigned long result = offset & ~(BITS_PER_LONG - 1); |
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| 244 | unsigned long tmp; |
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| 245 | |||
| 246 | if (offset >= size) |
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| 247 | return size; |
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| 248 | p += BITOP_WORD(offset); |
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| 249 | size -= result; |
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| 250 | offset &= (BITS_PER_LONG - 1UL); |
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| 251 | if (offset) { |
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| 252 | tmp = ext2_swabp(p++); |
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| 253 | tmp &= (~0UL << offset); |
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| 254 | if (size < BITS_PER_LONG) |
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| 255 | goto found_first; |
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| 256 | if (tmp) |
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| 257 | goto found_middle; |
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| 258 | size -= BITS_PER_LONG; |
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| 259 | result += BITS_PER_LONG; |
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| 260 | } |
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| 261 | |||
| 262 | while (size & ~(BITS_PER_LONG - 1)) { |
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| 263 | tmp = *(p++); |
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| 264 | if (tmp) |
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| 265 | goto found_middle_swap; |
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| 266 | result += BITS_PER_LONG; |
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| 267 | size -= BITS_PER_LONG; |
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| 268 | } |
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| 269 | if (!size) |
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| 270 | return result; |
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| 271 | tmp = ext2_swabp(p); |
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| 272 | found_first: |
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| 273 | tmp &= (~0UL >> (BITS_PER_LONG - size)); |
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| 274 | if (tmp == 0UL) /* Are any bits set? */ |
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| 275 | return result + size; /* Nope. */ |
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| 276 | found_middle: |
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| 277 | return result + __ffs(tmp); |
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| 278 | |||
| 279 | found_middle_swap: |
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| 280 | return result + __ffs(ext2_swab(tmp)); |
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| 281 | } |
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| 282 | EXPORT_SYMBOL(find_next_bit_le); |
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| 283 | #endif |
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| 284 | |||
| 285 | #endif /* __BIG_ENDIAN */ |