--- /dev/null
+
+#include <stdbool.h>
+#include <stdint.h>
+#include "platform.h"
+#include "specialize.h"
+
+bool softfloat_isSigNaNF64UI( uint_fast64_t ui )
+{
+
+ return
+ ( ( ui>>51 & 0xFFF ) == 0xFFE )
+ && ( ui & UINT64_C( 0x0007FFFFFFFFFFFF ) );
+
+}
+