+#endif
+
+#if ! defined(HAS_FREXPL) && defined(HAS_ILOGBL) && defined(HAS_SCALBNL)
+long double
+Perl_my_frexpl(long double x, int *e) {
+ *e = x == 0.0L ? 0 : ilogbl(x) + 1;
+ return (scalbnl(x, -*e));
+}
+#endif
+
+/*
+=for apidoc Perl_signbit
+
+Return a non-zero integer if the sign bit on an NV is set, and 0 if
+it is not.
+
+If Configure detects this system has a signbit() that will work with
+our NVs, then we just use it via the #define in perl.h. Otherwise,
+fall back on this implementation. As a first pass, this gets everything
+right except -0.0. Alas, catching -0.0 is the main use for this function,
+so this is not too helpful yet. Still, at least we have the scaffolding
+in place to support other systems, should that prove useful.
+
+
+Configure notes: This function is called 'Perl_signbit' instead of a
+plain 'signbit' because it is easy to imagine a system having a signbit()
+function or macro that doesn't happen to work with our particular choice
+of NVs. We shouldn't just re-#define signbit as Perl_signbit and expect
+the standard system headers to be happy. Also, this is a no-context
+function (no pTHX_) because Perl_signbit() is usually re-#defined in
+perl.h as a simple macro call to the system's signbit().
+Users should just always call Perl_signbit().