1 files changed, 31 insertions, 0 deletions
diff --git a/lib/ffsdi2.c b/lib/ffsdi2.c
new file mode 100644
index 000000000..93afc6ce3
--- /dev/null
+++ b/lib/ffsdi2.c
@@ -0,0 +1,31 @@
+//===-- ffsdi2.c - Implement __ffsdi2 -------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements __ffsdi2 for the compiler_rt library.
+//
+//===----------------------------------------------------------------------===//
+
+#include "int_lib.h"
+
+// Returns: the index of the least significant 1-bit in a, or
+// the value zero if a is zero. The least significant bit is index one.
+
+si_int
+__ffsdi2(di_int a)
+{
+    dwords x;
+    x.all = a;
+    if (x.low == 0)
+    {
+        if (x.high == 0)
+            return 0;
+        return __builtin_ctz(x.high) + (1 + sizeof(si_int) * CHAR_BIT);
+    }
+    return __builtin_ctz(x.low) + 1;
+}