string/FreeBSD/ffs.3

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  34 .\"     @(#)ffs.3       8.2 (Berkeley) 4/19/94
  35 .\" $FreeBSD: src/lib/libc/string/ffs.3,v 1.6 2002/08/30 19:08:53 robert Exp $
  36 .\"
  37 .Dd April 19, 1994
  38 .Dt FFS 3
  39 .Os
  40 .Sh NAME
  41 .Nm ffs
  42 .Nd find first bit set in a bit string
  43 .Sh LIBRARY
  44 .Lb libc
  45 .Sh SYNOPSIS
  46 .In strings.h
  47 .Ft int
  48 .Fn ffs "int value"
  49 .Sh DESCRIPTION
  50 The
  51 .Fn ffs
  52 function finds the first bit set in
  53 .Fa value
  54 and returns the index of that bit.
  55 Bits are numbered starting from 1, starting at the right-most
  56 bit.
  57 A return value of 0 means that the argument was zero.
  58 .Sh SEE ALSO
  59 .Xr bitstring 3
  60 .Sh HISTORY
  61 The
  62 .Fn ffs
  63 function appeared in
  64 .Bx 4.3 .
  65 Its prototype existed previously in
  66 .Aq Pa string.h
  67 before it was moved to
  68 .Aq Pa strings.h
  69 for
  70 .St -p1003.1-2001
  71 compliance.