__FFS(9) Basic C Library Functions __FFS(9)NAME__ffs - find first set bit in word
SYNOPSIS
unsigned long __ffs(unsigned long word);
ARGUMENTS
word
The word to search
DESCRIPTION
Undefined if no bit exists, so code should check against 0 first.
COPYRIGHTKernel Hackers Manual 3.11 November 2013 __FFS(9)