ffs.3: Updated ffs() feature test macro requirements for glibc 2.12

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

diff --git a/man3/ffs.3 b/man3/ffs.3
index 7a5135df6e83b45571c9cf0e92a0d0e2dbbd2dab..a97ecc2c87c51fe69e9f6f4de5872cfa2e7cbc9f 100644 (file)
--- a/man3/ffs.3
+++ b/man3/ffs.3
@@ -37,14 +37,36 @@ ffs, ffsl, ffsll \- find first bit set in a word
 .sp
 .BI "int ffs(int " i );
 .sp
-.B #define _GNU_SOURCE
-.br
 .B #include <string.h>
 .sp
 .BI "int ffsl(long int " i );
 .sp
 .BI "int ffsll(long long int " i );
 .fi
+.sp
+.in -4n
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.in
+.PD 0
+.ad l
+.sp
+.BR ffs ():
+.RS 4
+.TP 4
+Since glibc 2.12:
+_SVID_SOURCE || _BSD_SOURCE ||
+_POSIX_C_SOURCE\ >=\ 200809L || _XOPEN_SOURCE\ >=\ 700 ||
+.TP
+Before glibc 2.12:
+none
+.RE
+.PP
+.BR ffsl (),
+.BR ffsll ():
+_GNU_SOURCE
+.ad
+.PD
 .SH DESCRIPTION
 The
 .BR ffs ()