bitmap_bitremap (9) - Linux Man Pages
bitmap_bitremap: Apply map defined by a pair of bitmaps to a single bit
bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
oldbit, const unsigned long *old, const unsigned long *new, int bits);
- bit position to be mapped
- defines domain of map
- defines range of map
- number of bits in each of these bitmaps
Let old and new define a mapping of bit positions, such that whatever position is held by the n-th set bit in old is mapped to the n-th set bit in new. In the more general case, allowing for the possibility that the weight 'w' of new is less than the weight of old, map the position of the n-th set bit in old to the position of the m-th set bit in new, where m == n % w.
The positions of unset bits in old are mapped to themselves (the identify map).
Apply the above specified mapping to bit position oldbit, returning the new bit position.
For example, lets say that old has bits 4 through 7 set, and new has bits 12 through 15 set. This defines the mapping of bit position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other bit positions unchanged. So if say oldbit is 5, then this routine returns 13.