1 files changed, 42 insertions, 0 deletions
diff --git a/libc/misc/ffs.c b/libc/misc/ffs.c
new file mode 100644
index 0000000..e4afe7a
--- /dev/null
+++ b/libc/misc/ffs.c
@@ -0,0 +1,42 @@
+/*
+FUNCTION
+	<<ffs>>---find first bit set in a word
+
+INDEX
+	ffs
+
+ANSI_SYNOPSIS
+	int ffs(int <[word]>);
+
+TRAD_SYNOPSIS
+	int ffs(<[word]>);
+
+DESCRIPTION
+
+<<ffs>> returns the first bit set in a word.
+
+RETURNS
+<<ffs>> returns 0 if <[c]> is 0, 1 if <[c]> is odd, 2 if <[c]> is a multiple of
+2, etc.
+
+PORTABILITY
+<<ffs>> is not ANSI C.
+
+No supporting OS subroutines are required.  */
+
+int
+ffs (word)
+     int word;
+{
+  int i;
+
+  if (!word)
+    return 0;
+
+  i = 0;
+  for (;;)
+    {
+      if (((1 << i++) & word) != 0)
+	return i;
+    }
+}