71 lines
1.6 KiB
C
71 lines
1.6 KiB
C
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#include <linux/bitops.h>
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#include <linux/module.h>
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/**
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* find_next_bit - find the first set bit in a memory region
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* @addr: The address to base the search on
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* @offset: The bitnumber to start searching at
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* @size: The maximum size to search
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*/
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int find_next_bit(const unsigned long *addr, int size, int offset)
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{
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const unsigned long *p = addr + (offset >> 5);
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int set = 0, bit = offset & 31, res;
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if (bit) {
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/*
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* Look for nonzero in the first 32 bits:
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*/
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__asm__("bsfl %1,%0\n\t"
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"jne 1f\n\t"
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"movl $32, %0\n"
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"1:"
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: "=r" (set)
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: "r" (*p >> bit));
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if (set < (32 - bit))
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return set + offset;
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set = 32 - bit;
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p++;
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}
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/*
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* No set bit yet, search remaining full words for a bit
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*/
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res = find_first_bit (p, size - 32 * (p - addr));
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return (offset + set + res);
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}
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EXPORT_SYMBOL(find_next_bit);
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/**
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* find_next_zero_bit - find the first zero bit in a memory region
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* @addr: The address to base the search on
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* @offset: The bitnumber to start searching at
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* @size: The maximum size to search
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*/
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int find_next_zero_bit(const unsigned long *addr, int size, int offset)
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{
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unsigned long * p = ((unsigned long *) addr) + (offset >> 5);
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int set = 0, bit = offset & 31, res;
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if (bit) {
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/*
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* Look for zero in the first 32 bits.
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*/
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__asm__("bsfl %1,%0\n\t"
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"jne 1f\n\t"
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"movl $32, %0\n"
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"1:"
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: "=r" (set)
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: "r" (~(*p >> bit)));
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if (set < (32 - bit))
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return set + offset;
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set = 32 - bit;
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p++;
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}
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/*
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* No zero yet, search remaining full bytes for a zero
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*/
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res = find_first_zero_bit (p, size - 32 * (p - (unsigned long *) addr));
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return (offset + set + res);
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}
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EXPORT_SYMBOL(find_next_zero_bit);
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