fls(9) centos man page | unix.com

FLS(9)							     Basic C Library Functions							    FLS(9)

NAME
       fls - find last set bit in word

SYNOPSIS
       int fls(int x);

ARGUMENTS
       x
	   the word to search

DESCRIPTION
       This is defined in a similar way as the libc and compiler builtin ffs, but returns the position of the most significant set bit.

       fls(value) returns 0 if value is 0 or the position of the last set bit if value is nonzero. The last (most significant) bit is at position
       32.

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014								    FLS(9)