LXR linux/tools/testing/radix-tree/bitmap.c

   1/* lib/bitmap.c pulls in at least two other files. */
   2
   3#include <linux/bitmap.h>
   4
   5void bitmap_clear(unsigned long *map, unsigned int start, int len)
   6{
   7        unsigned long *p = map + BIT_WORD(start);
   8        const unsigned int size = start + len;
   9        int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
  10        unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
  11
  12        while (len - bits_to_clear >= 0) {
  13                *p &= ~mask_to_clear;
  14                len -= bits_to_clear;
  15                bits_to_clear = BITS_PER_LONG;
  16                mask_to_clear = ~0UL;
  17                p++;
  18        }
  19        if (len) {
  20                mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
  21                *p &= ~mask_to_clear;
  22        }
  23}
  24