- for (s = find_first_bit(src, bits);
- s < bits;
- s = find_next_bit(src, bits, s + 1)) {
- int x = bitmap_pos_to_ord(old, s, bits);
- int y = bitmap_ord_to_pos(new, x, bits);
- set_bit(y, dst);
+
+ w = bitmap_weight(new, bits);
+ for (oldbit = find_first_bit(src, bits);
+ oldbit < bits;
+ oldbit = find_next_bit(src, bits, oldbit + 1)) {
+ int n = bitmap_pos_to_ord(old, oldbit, bits);
+ if (n < 0 || w == 0)
+ set_bit(oldbit, dst); /* identity map */
+ else
+ set_bit(bitmap_ord_to_pos(new, n % w, bits), dst);