__swap_double
extern double __swap_double(double arg);
#define B_SWAP_DOUBLE(arg) __swap_double(arg)
#define B_HOST_TO_BENDIAN_DOUBLE(arg) __swap_double(arg)
#define B_BENDIAN_TO_HOST_DOUBLE(arg) __swap_double(arg)
#define B_HOST_TO_LENDIAN_DOUBLE(arg) __swap_double(arg)
#define B_LENDIAN_TO_HOST_DOUBLE(arg) __swap_double(arg)
data = __swap_double(data);
const double roundtrip = __swap_double(__swap_double(kNaN));
CPPUNIT_ASSERT_EQUAL(kNumber, __swap_double(__swap_double(kNumber)));
CPPUNIT_ASSERT_EQUAL(kInfinity, __swap_double(__swap_double(kInfinity)));