FFS(9) Basic C Library Functions FFS(9)NAMEffs - find first set bit in word
int ffs(int x);
the word to search
This is defined the same way as the libc and compiler builtin ffs
routines, therefore differs in spirit from the other bitops.
ffs(value) returns 0 if value is 0 or the position of the first set bit
if value is nonzero. The first (least significant) bit is at position
COPYRIGHTKernel Hackers Manual 2.6. November 2013 FFS(9)