fls - find last set bit in word

int fls(int  x );

x
    the word to search

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.