76 lines
1.8 KiB
C
76 lines
1.8 KiB
C
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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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