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76 lines
1.9 KiB
76 lines
1.9 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* MSB0 numbered special bitops handling. |
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* |
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* The bits are numbered: |
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* |0..............63|64............127|128...........191|192...........255| |
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* |
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* The reason for this bit numbering is the fact that the hardware sets bits |
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* in a bitmap starting at bit 0 (MSB) and we don't want to scan the bitmap |
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* from the 'wrong end'. |
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*/ |
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#include <linux/compiler.h> |
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#include <linux/bitops.h> |
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#include <linux/export.h> |
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unsigned long find_first_bit_inv(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) /* Are any bits set? */ |
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return result + size; /* Nope. */ |
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found: |
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return result + (__fls(tmp) ^ (BITS_PER_LONG - 1)); |
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} |
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EXPORT_SYMBOL(find_first_bit_inv); |
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unsigned long find_next_bit_inv(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 + (offset / BITS_PER_LONG); |
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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) /* Are any bits set? */ |
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return result + size; /* Nope. */ |
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found_middle: |
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return result + (__fls(tmp) ^ (BITS_PER_LONG - 1)); |
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} |
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EXPORT_SYMBOL(find_next_bit_inv);
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