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  */
  10 int 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 }
  36 EXPORT_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  */
  44 int find_next_zero_bit(const unsigned long *addr, int size, int offset)
  45 {
  46         unsigned long * p = ((unsigned long *) 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 - (unsigned long *) addr));
  68         return (offset + set + res);
  69 }
  70 EXPORT_SYMBOL(find_next_zero_bit);