--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtommath/bn_mp_get_long_long.c	Sat Jun 24 22:51:45 2017 +0800
@@ -0,0 +1,41 @@
+#include <tommath_private.h>
+#ifdef BN_MP_GET_LONG_LONG_C
+/* LibTomMath, multiple-precision integer library -- Tom St Denis
+ *
+ * LibTomMath is a library that provides multiple-precision
+ * integer arithmetic as well as number theoretic functionality.
+ *
+ * The library was designed directly after the MPI library by
+ * Michael Fromberger but has been written from scratch with
+ * additional optimizations in place.
+ *
+ * The library is free for all purposes without any express
+ * guarantee it works.
+ *
+ * Tom St Denis, [email protected], http://libtom.org
+ */
+
+/* get the lower unsigned long long of an mp_int, platform dependent */
+unsigned long long mp_get_long_long (mp_int * a)
+{
+  int i;
+  unsigned long long res;
+
+  if (a->used == 0) {
+     return 0;
+  }
+
+  /* get number of digits of the lsb we have to read */
+  i = MIN(a->used,(int)(((sizeof(unsigned long long) * CHAR_BIT) + DIGIT_BIT - 1) / DIGIT_BIT)) - 1;
+
+  /* get most significant digit of result */
+  res = DIGIT(a,i);
+
+#if DIGIT_BIT < 64
+  while (--i >= 0) {
+    res = (res << DIGIT_BIT) | DIGIT(a,i);
+  }
+#endif
+  return res;
+}
+#endif