embox

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/**
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 * @file
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 *
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 * @date 21.10.2013
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 * @author Eldar Abusalimov
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 */
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#include <limits.h>
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#include <stdbool.h>
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#include <lib/libds/bit.h>
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#include <lib/libds/bitmap.h>
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unsigned int __bitmap_find_bit(const unsigned long *bitmap, unsigned int nbits,
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    unsigned int start, bool zero_bit) {
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	const unsigned long *first;
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	const unsigned long *last;
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	const unsigned long *iter;
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	unsigned long bits;
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	if (start >= nbits) {
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		return nbits;
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	}
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	first = bitmap + BITMAP_OFFSET(start);
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	last = bitmap + BITMAP_OFFSET(nbits - 1);
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	for (iter = first; iter <= last; iter++) {
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		bits = *iter;
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		if (zero_bit) {
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			bits = ~bits;
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		}
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		if (iter == first) {
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			bits &= ~0UL << BITMAP_SHIFT(start);
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		}
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		if (iter == last) {
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			bits &= ~0UL >> (LONG_BIT - 1 - BITMAP_SHIFT(nbits - 1));
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		}
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		if (bits) {
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			return LONG_BIT * (iter - bitmap) + bit_ctz(bits);
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		}
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	}
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	return nbits;
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}
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