ndnboost: Include boost::iostreams for internal use.
diff --git a/include/ndnboost/random/detail/signed_unsigned_tools.hpp b/include/ndnboost/random/detail/signed_unsigned_tools.hpp
new file mode 100644
index 0000000..8fcb1b6
--- /dev/null
+++ b/include/ndnboost/random/detail/signed_unsigned_tools.hpp
@@ -0,0 +1,89 @@
+/* boost random/detail/signed_unsigned_tools.hpp header file
+ *
+ * Copyright Jens Maurer 2006
+ * Distributed under the Boost Software License, Version 1.0. (See
+ * accompanying file LICENSE_1_0.txt or copy at
+ * http://www.boost.org/LICENSE_1_0.txt)
+ *
+ * See http://www.boost.org for most recent version including documentation.
+ */
+
+#ifndef NDNBOOST_RANDOM_DETAIL_SIGNED_UNSIGNED_TOOLS
+#define NDNBOOST_RANDOM_DETAIL_SIGNED_UNSIGNED_TOOLS
+
+#include <ndnboost/limits.hpp>
+#include <ndnboost/config.hpp>
+#include <ndnboost/type_traits/make_unsigned.hpp>
+
+namespace ndnboost {
+namespace random {
+namespace detail {
+
+
+/*
+ * Compute x - y, we know that x >= y, return an unsigned value.
+ */
+
+template<class T, bool sgn = std::numeric_limits<T>::is_signed>
+struct subtract { };
+
+template<class T>
+struct subtract<T, /* signed */ false>
+{
+ typedef T result_type;
+ result_type operator()(T x, T y) { return x - y; }
+};
+
+template<class T>
+struct subtract<T, /* signed */ true>
+{
+ typedef typename make_unsigned<T>::type result_type;
+ result_type operator()(T x, T y)
+ {
+ if (y >= 0) // because x >= y, it follows that x >= 0, too
+ return result_type(x) - result_type(y);
+ if (x >= 0) // y < 0
+ // avoid the nasty two's complement case for y == min()
+ return result_type(x) + result_type(-(y+1)) + 1;
+ // both x and y are negative: no signed overflow
+ return result_type(x - y);
+ }
+};
+
+/*
+ * Compute x + y, x is unsigned, result fits in type of "y".
+ */
+
+template<class T1, class T2, bool sgn = std::numeric_limits<T2>::is_signed>
+struct add { };
+
+template<class T1, class T2>
+struct add<T1, T2, /* signed */ false>
+{
+ typedef T2 result_type;
+ result_type operator()(T1 x, T2 y) { return T2(x) + y; }
+};
+
+template<class T1, class T2>
+struct add<T1, T2, /* signed */ true>
+{
+ typedef T2 result_type;
+ result_type operator()(T1 x, T2 y)
+ {
+ if (y >= 0)
+ return T2(x) + y;
+ // y < 0
+ if (x > T1(-(y+1))) // result >= 0 after subtraction
+ // avoid the nasty two's complement edge case for y == min()
+ return T2(x - T1(-(y+1)) - 1);
+ // abs(x) < abs(y), thus T2 able to represent x
+ return T2(x) + y;
+ }
+};
+
+} // namespace detail
+} // namespace random
+} // namespace ndnboost
+
+#endif // NDNBOOST_RANDOM_DETAIL_SIGNED_UNSIGNED_TOOLS
+