3 files changed, 31 insertions, 0 deletions
diff --git a/opentrack-compat/CMakeLists.txt b/opentrack-compat/CMakeLists.txt
index 6f745701..2bbb496c 100644
--- a/opentrack-compat/CMakeLists.txt
+++ b/opentrack-compat/CMakeLists.txt
@@ -2,3 +2,7 @@ opentrack_boilerplate(opentrack-compat NO-COMPAT BIN)
 if(NOT WIN32 AND NOT APPLE)
     target_link_libraries(opentrack-compat rt)
 endif()
+if(CMAKE_COMPILER_IS_GNUCXX)
+    set_source_files_properties(nan.cpp PROPERTIES
+        COMPILE_FLAGS "-fno-fast-math -fno-finite-math-only -O0")
+endif()
diff --git a/opentrack-compat/nan.cpp b/opentrack-compat/nan.cpp
new file mode 100644
index 00000000..6c4b1f6d
--- /dev/null
+++ b/opentrack-compat/nan.cpp
@@ -0,0 +1,16 @@
+#include <cmath>
+
+#if defined(__GNUC__)
+extern "C" bool __attribute__ ((noinline)) nanp(double value)
+#elif defined(_WIN32)
+extern "C" __declspec(noinline) bool nanp(double value)
+#else
+extern "C" bool nanp(double value)
+#endif
+{
+    using std::isnan;
+    using std::isinf;
+
+    const volatile double x = value;
+    return isnan(x) || isinf(x);
+}
diff --git a/opentrack-compat/nan.hpp b/opentrack-compat/nan.hpp
new file mode 100644
index 00000000..f9e5cc1e
--- /dev/null
+++ b/opentrack-compat/nan.hpp
@@ -0,0 +1,11 @@
+#pragma once
+
+#include "export.hpp"
+
+#if defined(__GNUC__)
+extern "C" OPENTRACK_COMPAT_EXPORT bool __attribute__ ((noinline)) nanp(double value);
+#elif defined(_WIN32)
+extern "C" __declspec(noinline) OPENTRACK_COMPAT_EXPORT bool nanp(double value);
+#else
+extern "C" OPENTRACK_COMPAT_EXPORT bool nanp(double value);
+#endif