Rearrange sources (#4997)

src/libxrpl/basics/mulDiv.cpp

@@ -0,0 +1,42 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of rippled: https://github.com/ripple/rippled
+    Copyright (c) 2012-2015 Ripple Labs Inc.
+
+    Permission to use, copy, modify, and/or distribute this software for any
+    purpose  with  or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#include <ripple/basics/mulDiv.h>
+#include <boost/multiprecision/cpp_int.hpp>
+#include <optional>
+
+namespace ripple {
+
+std::optional<std::uint64_t>
+mulDiv(std::uint64_t value, std::uint64_t mul, std::uint64_t div)
+{
+    using namespace boost::multiprecision;
+
+    uint128_t result;
+    result = multiply(result, value, mul);
+
+    result /= div;
+
+    if (result > ripple::muldiv_max)
+        return std::nullopt;
+
+    return static_cast<std::uint64_t>(result);
+}
+
+}  // namespace ripple