BITMAP_REMAP(9)                   Basic Kernel Library Functions                  BITMAP_REMAP(9)



NAME
       bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap

SYNOPSIS
       void bitmap_remap(unsigned long * dst, const unsigned long * src,
                         const unsigned long * old, const unsigned long * new,
                         unsigned int nbits);

ARGUMENTS
       dst
           remapped result

       src
           subset to be remapped

       old
           defines domain of map

       new
           defines range of map

       nbits
           number of bits in each of these bitmaps

DESCRIPTION
       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.

       If either of the old and new bitmaps are empty, or if src and dst point to the same
       location, then this routine copies src to dst.

       The positions of unset bits in old are mapped to themselves (the identify map).

       Apply the above specified mapping to src, placing the result in dst, clearing any bits
       previously set in dst.

       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 src comes into this routine with bits 1, 5
       and 7 set, then dst should leave with bits 1, 13 and 15 set.

COPYRIGHT
Kernel Hackers Manual 4.8.                 January 2017                           BITMAP_REMAP(9)