FS(3)                   BSD Library Functions Manual                   FS(3)

NAME
     ffs, ffsl, fls, flsl -- find first or last bit set in a bit string

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     ##include <>

     int
     ffs(int value);

     int
     ffsl(long value);

     int
     fls(int value);

     int
     flsl(long value);

DESCRIPTION
     The ffs() and ffsl() functions find the first bit set in value and return
     the index of that bit.

     The fls() and flsl() functions find the last bit set in value and return
     the index of that bit.

     Bits are numbered starting from 1, starting at the right-most (least sig-
     nificant) bit.  A return value of zero from any of these functions means
     that the argument was zero.

SEE ALSO
     bitstring(3)

HISTORY
     The ffs() function appeared in 4.3BSD.  Its prototype existed previously
     in  before it was moved to  for IE Std 1003.1-2001
     (``POSIX.1'') compliance.

     The ffsl(), fls() and flsl() functions appeared in FreeBSD 5.3.

BSD                            January 13, 2004                            BSD