random: use TinyMT instead of XorShift

libraries/libstratosphere/source/os/impl/os_random_impl.os.horizon.cpp

@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) 2018-2019 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <stratosphere.hpp>
+
+namespace ams::os::impl {
+
+    void InitializeRandomImpl(util::TinyMT *mt) {
+        /* Retrieve entropy from kernel. */
+        u32 seed[4];
+        static_assert(util::size(seed) == util::TinyMT::NumStateWords);
+
+        /* Nintendo does not check the result of these invocations, but we will for safety. */
+        /* Nintendo uses entropy values 0, 1 to seed the public TinyMT random, and values */
+        /* 2, 3 to seed os::detail::RngManager's private TinyMT random. */
+        R_ASSERT(svcGetInfo(reinterpret_cast<u64 *>(&seed[0]), InfoType_RandomEntropy, INVALID_HANDLE, 0));
+        R_ASSERT(svcGetInfo(reinterpret_cast<u64 *>(&seed[2]), InfoType_RandomEntropy, INVALID_HANDLE, 1));
+
+        mt->Initialize(seed, util::size(seed));
+    }
+
+}