From 8cbd4e746f40c750809e34d04c0298e0a5ff6f42 Mon Sep 17 00:00:00 2001
From: claudio <>
Date: Fri, 24 Oct 2025 11:30:06 +0000
Subject: Implement ffsl() and ffsll() using the compiler builtin
 __builtin_ctzl now that all archs use at least gcc4. ffsl() and ffsll() are
 now part of POSIX. OK deraadt@, input from miod@ and jsg@

---
 src/lib/libc/string/Makefile.inc | 12 ++++++------
 src/lib/libc/string/ffs.3        | 31 ++++++++++++++++++++++++++-----
 src/lib/libc/string/ffsl.c       | 17 +++++++++++++++++
 src/lib/libc/string/ffsll.c      | 17 +++++++++++++++++
 4 files changed, 66 insertions(+), 11 deletions(-)
 create mode 100644 src/lib/libc/string/ffsl.c
 create mode 100644 src/lib/libc/string/ffsll.c

(limited to 'src/lib')

diff --git a/src/lib/libc/string/Makefile.inc b/src/lib/libc/string/Makefile.inc
index 204ca1b266..f8b6330453 100644
--- a/src/lib/libc/string/Makefile.inc
+++ b/src/lib/libc/string/Makefile.inc
@@ -1,13 +1,13 @@
-#	$OpenBSD: Makefile.inc,v 1.40 2024/07/14 09:51:18 jca Exp $
+#	$OpenBSD: Makefile.inc,v 1.41 2025/10/24 11:30:06 claudio Exp $
 
 # string sources
 .PATH: ${LIBCSRCDIR}/arch/${MACHINE_CPU}/string ${LIBCSRCDIR}/string
 
-SRCS+=	explicit_bzero.c memccpy.c memmem.c memrchr.c stpcpy.c stpncpy.c \
-	strcasecmp.c strcasecmp_l.c strcasestr.c strcoll.c strcoll_l.c \
-	strdup.c strerror.c strerror_l.c strerror_r.c strmode.c \
-	strndup.c strnlen.c strsignal.c strtok.c strxfrm.c strxfrm_l.c \
-	timingsafe_bcmp.c timingsafe_memcmp.c \
+SRCS+=	explicit_bzero.c ffsl.c ffsll.c memccpy.c memmem.c memrchr.c \
+	stpcpy.c stpncpy.c strcasecmp.c strcasecmp_l.c strcasestr.c \
+	strcoll.c strcoll_l.c strdup.c strerror.c strerror_l.c strerror_r.c \
+	strmode.c strndup.c strnlen.c strsignal.c strtok.c strxfrm.c \
+	strxfrm_l.c timingsafe_bcmp.c timingsafe_memcmp.c \
 	wcscat.c wcschr.c wcscmp.c wcscpy.c wcscspn.c wcslcat.c wcslcpy.c \
 	wcslen.c wcsncat.c wcsncmp.c wcsncpy.c wcsnlen.c wcspbrk.c wcsrchr.c \
 	wcsspn.c wcsstr.c wcstok.c wcswcs.c wcswidth.c wmemchr.c wmemcmp.c \
diff --git a/src/lib/libc/string/ffs.3 b/src/lib/libc/string/ffs.3
index e78ab99e8f..630db1c584 100644
--- a/src/lib/libc/string/ffs.3
+++ b/src/lib/libc/string/ffs.3
@@ -27,22 +27,31 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.\"	$OpenBSD: ffs.3,v 1.11 2019/08/30 18:35:03 deraadt Exp $
+.\"	$OpenBSD: ffs.3,v 1.12 2025/10/24 11:30:06 claudio Exp $
 .\"
-.Dd $Mdocdate: August 30 2019 $
+.Dd $Mdocdate: October 24 2025 $
 .Dt FFS 3
 .Os
 .Sh NAME
-.Nm ffs
+.Nm ffs ,
+.Nm ffsl ,
+.Nm ffsll
 .Nd find first bit set in a bit string
 .Sh SYNOPSIS
 .In strings.h
 .Ft int
 .Fn ffs "int value"
+.Ft int
+.Fn ffsl "long value"
+.Ft int
+.Fn ffsll "long long value"
 .Sh DESCRIPTION
 The
-.Fn ffs
-function finds the first bit set in
+.Fn ffs ,
+.Fn ffsl
+and
+.Fn ffsll
+functions find the first bit set in
 .Fa value
 and returns the index of that bit.
 Bits are numbered starting from 1, starting at the rightmost bit.
@@ -54,8 +63,20 @@ The
 .Fn ffs
 function conforms to
 .St -p1003.1-2008 .
+The
+.Fn ffsl
+and
+.Fn ffsll
+functions conform to
+.St -p1003.1-2024 .
 .Sh HISTORY
 The
 .Fn ffs
 function first appeared in
 .Bx 4.2 .
+The
+.Fn ffsl
+and
+.Fn ffsll
+functions first appeared in
+.Ox 7.9 .
diff --git a/src/lib/libc/string/ffsl.c b/src/lib/libc/string/ffsl.c
new file mode 100644
index 0000000000..182318c3d6
--- /dev/null
+++ b/src/lib/libc/string/ffsl.c
@@ -0,0 +1,17 @@
+/*	$OpenBSD: ffsl.c,v 1.1 2025/10/24 11:30:06 claudio Exp $	*/
+
+/*
+ * Public domain.
+ * Written by Claudio Jeker.
+ */
+
+#include <strings.h>
+
+/*
+ * ffs -- find the first (least significant) bit set
+ */
+int
+ffsl(long mask)
+{
+	return (mask ? __builtin_ctzl(mask) + 1 : 0);
+}
diff --git a/src/lib/libc/string/ffsll.c b/src/lib/libc/string/ffsll.c
new file mode 100644
index 0000000000..9370c5ae41
--- /dev/null
+++ b/src/lib/libc/string/ffsll.c
@@ -0,0 +1,17 @@
+/*	$OpenBSD: ffsll.c,v 1.1 2025/10/24 11:30:06 claudio Exp $	*/
+
+/*
+ * Public domain.
+ * Written by Claudio Jeker.
+ */
+
+#include <strings.h>
+
+/*
+ * ffs -- find the first (least significant) bit set
+ */
+int
+ffsll(long long mask)
+{
+	return (mask ? __builtin_ctzll(mask) + 1 : 0);
+}
-- 
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