NAME    [Toc]    [Back]

       ffs - General: Finds the first set bit in a mask

SYNOPSIS    [Toc]    [Back]

       int ffs(
               long mask );

ARGUMENTS    [Toc]    [Back]

       Specifies a bit mask with 0 (zero) or more bits set.

DESCRIPTION    [Toc]    [Back]

       The  ffs routine returns the bit position of the first bit
       you set in the mask argument.  The scan proceeds from  the
       least  significant  bit to the most significant bit of the
       mask.

NOTES    [Toc]    [Back]

       The  ffs  routine  duplicates  the  behavior  of  the  ffs
       instruction on the DIGITAL VAX series or computers.  It is
       not present in architectures that implement  its  function
       in hardware or through compiler inline substitution.

       The  ffs  routine  is useful for translating bits in a bit
       mask into bit positions. For example, the signal  handling
       code uses it to analyze the signal mask.

RETURN VALUES    [Toc]    [Back]

       Upon  successful  completion, ffs returns the bit position
       of the first bit set in the mask. If no bits were  set  in
       the mask, ffs returns the value 0 (zero).



                                                          ffs(9r)