centos man page for bitmap_pos_to_ord

BITMAP_POS_TO_ORD(9)					  Basic Kernel Library Functions				      BITMAP_POS_TO_ORD(9)

NAME
       bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap

SYNOPSIS
       int bitmap_pos_to_ord(const unsigned long * buf, int pos, int bits);

ARGUMENTS
       buf
	   pointer to a bitmap

       pos
	   a bit position in buf (0 <= pos < bits)

       bits
	   number of valid bit positions in buf

DESCRIPTION
       Map the bit at position pos in buf (of length bits) to the ordinal of which set bit it is. If it is not set or if pos is not a valid bit
       position, map to -1.

       If for example, just bits 4 through 7 are set in buf, then pos values 4 through 7 will get mapped to 0 through 3, respectively, and other
       pos values will get mapped to 0. When pos value 7 gets mapped to (returns) ord value 3 in this example, that means that bit 7 is the 3rd
       (starting with 0th) set bit in buf.

       The bit positions 0 through bits are valid positions in buf.

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014						      BITMAP_POS_TO_ORD(9)