LXR linux/arch/i386/lib/bitops.c

   1#include <linux/bitops.h>
   2#include <linux/module.h>
   3
   4/**
   5 * find_next_bit - find the first set bit in a memory region
   6 * @addr: The address to base the search on
   7 * @offset: The bitnumber to start searching at
   8 * @size: The maximum size to search
   9 */
  10int find_next_bit(const unsigned long *addr, int size, int offset)
  11{
  12        const unsigned long *p = addr + (offset >> 5);
  13        int set = 0, bit = offset & 31, res;
  14
  15        if (bit) {
  16                /*
  17                 * Look for nonzero in the first 32 bits:
  18                 */
  19                __asm__("bsfl %1,%0\n\t"
  20                        "jne 1f\n\t"
  21                        "movl $32, %0\n"
  22                        "1:"
  23                        : "=r" (set)
  24                        : "r" (*p >> bit));
  25                if (set < (32 - bit))
  26                        return set + offset;
  27                set = 32 - bit;
  28                p++;
  29        }
  30        /*
  31         * No set bit yet, search remaining full words for a bit
  32         */
  33        res = find_first_bit (p, size - 32 * (p - addr));
  34        return (offset + set + res);
  35}
  36EXPORT_SYMBOL(find_next_bit);
  37
  38/**
  39 * find_next_zero_bit - find the first zero bit in a memory region
  40 * @addr: The address to base the search on
  41 * @offset: The bitnumber to start searching at
  42 * @size: The maximum size to search
  43 */
  44int find_next_zero_bit(const unsigned long *addr, int size, int offset)
  45{
  46        const unsigned long *p = addr + (offset >> 5);
  47        int set = 0, bit = offset & 31, res;
  48
  49        if (bit) {
  50                /*
  51                 * Look for zero in the first 32 bits.
  52                 */
  53                __asm__("bsfl %1,%0\n\t"
  54                        "jne 1f\n\t"
  55                        "movl $32, %0\n"
  56                        "1:"
  57                        : "=r" (set)
  58                        : "r" (~(*p >> bit)));
  59                if (set < (32 - bit))
  60                        return set + offset;
  61                set = 32 - bit;
  62                p++;
  63        }
  64        /*
  65         * No zero yet, search remaining full bytes for a zero
  66         */
  67        res = find_first_zero_bit(p, size - 32 * (p - addr));
  68        return (offset + set + res);
  69}
  70EXPORT_SYMBOL(find_next_zero_bit);
  71