1 files changed, 54 insertions, 0 deletions
diff --git a/libc/string/ffs.c b/libc/string/ffs.c
new file mode 100644
index 000000000..fc76e6c70
--- /dev/null
+++ b/libc/string/ffs.c
@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2002     Manuel Novoa III
+ * Copyright (C) 2000-2005 Erik Andersen <andersen@uclibc.org>
+ *
+ * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
+ */
+
+/* ffsl,ffsll */
+
+#include "_string.h"
+
+int attribute_hidden __ffs(int i)
+{
+#if 1
+	/* inlined binary search method */
+	char n = 1;
+#if UINT_MAX == 0xffffU
+	/* nothing to do here -- just trying to avoiding possible problems */
+#elif UINT_MAX == 0xffffffffU
+	if (!(i & 0xffff)) {
+		n += 16;
+		i >>= 16;
+	}
+#else
+#error ffs needs rewriting!
+#endif
+
+	if (!(i & 0xff)) {
+		n += 8;
+		i >>= 8;
+	}
+	if (!(i & 0x0f)) {
+		n += 4;
+		i >>= 4;
+	}
+	if (!(i & 0x03)) {
+		n += 2;
+		i >>= 2;
+	}
+	return (i) ? (n + ((i+1) & 0x01)) : 0;
+
+#else
+	/* linear search -- slow, but small */
+	int n;
+
+	for (n = 0 ; i ; ++n) {
+		i >>= 1;
+	}
+	
+	return n;
+#endif
+}
+
+strong_alias(__ffs,ffs)