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ffs(3)

NAME

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

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <strings.h>

     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 <string.h> before it was moved to <strings.h> for IEEE Std 1003.1-2001
     (``POSIX.1'') compliance.

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

FreeBSD 5.4		       January 13, 2004 		   FreeBSD 5.4

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