bug fix on the incorrectly modified ulp() function on native ieee754 floating-point numbers

Author: Ravenwater

include/universal/native/ieee754_numeric.hpp

@@ -16,7 +16,8 @@ namespace sw { namespace universal {
 		typename = typename ::std::enable_if< ::std::is_floating_point<Real>::value, Real >::type
 	>
 	inline Real ulp(const Real& a) {
-		return std::nextafter(a, Real(INFINITY)) - a;
+		Real next = ((a < 0) ? std::nextafter(a, Real(-INFINITY)) : std::nextafter(a, Real(+INFINITY)));
+		return next - a;
 	}
 
 	// check if the floating-point number is zero

include/universal/number/cfloat/cfloat.hpp

@@ -121,7 +121,7 @@ using fp8e5m2  = cfloat<8, 5, std::uint8_t, true, true, false>;
 // ShowRepresentations prints the different output formats for the Scalar type
 // TODO: guard with cfloat trait
 template<typename Scalar>
-void ShowRepresentations(std::ostream& ostr, float f) {
+void ShowRepresentations(std::ostream& ostr, Scalar f) {
 	auto oldprec = ostr.precision(); // save stream state
 
 	constexpr int max_digits10 = std::numeric_limits<Scalar>::max_digits10; 	// floating-point attribute for printing scientific format

include/universal/number/qd/math/pow.hpp

@@ -28,14 +28,14 @@ namespace sw { namespace universal {
     //   NOTE:  0^0 causes an error.
     qd npwr(const qd& a, int n) {
         if (n == 0) {
-#if DOUBLEDOUBLE_THROW_ARITHMETIC_EXCEPTION
+#if QUADDOUBLE_THROW_ARITHMETIC_EXCEPTION
             if (a.iszero()) throw qd_invalid_argument();
-#else // ! DOUBLEDOUBLE_THROW_ARITHMETIC_EXCEPTION
+#else // ! QUADDOUBLE_THROW_ARITHMETIC_EXCEPTION
             if (a.iszero()) {
                 std::cerr << "(npwr): Invalid argument\n";
                 return qd(SpecificValue::snan);
             }
-#endif // ! DOUBLEDOUBLE_THROW_ARITHMETIC_EXCEPTION
+#endif // ! QUADDOUBLE_THROW_ARITHMETIC_EXCEPTION
             return 1.0;
         }
 

static/cfloat/conversion/float_conversion.cpp

@@ -19,7 +19,7 @@
 #include <universal/verification/cfloat_test_suite.hpp>
 //#include <universal/number/cfloat/table.hpp> // only used for value table generation
 
-#if BIT_CAST_IS_CONSEXPR
+#if BIT_CAST_IS_CONSTEXPR
 void ToNativeBug() {  // now resolved... exponentiation was incorrect
 	using namespace sw::universal;
 	constexpr size_t nbits = 32;
@@ -44,12 +44,12 @@ void ToNativeBug() {  // now resolved... exponentiation was incorrect
 	// bit cast
 	uint32_t bc = std::bit_cast<uint32_t, float>(f);
 	std::cout << "float    : " << to_binary(f) << '\n';
-	std::cout << "smask    : " << to_binary(ieee754_parameter<float>::smask, 32, false) << '\n';
-	std::cout << "emask    : " << to_binary(ieee754_parameter<float>::emask, 32, false) << '\n';
-	std::cout << "fmask    : " << to_binary(ieee754_parameter<float>::fmask, 32, false) << '\n';
-	std::cout << "smask+bc : " << to_binary((ieee754_parameter<float>::smask & bc), 32, false) << '\n';
-	std::cout << "emask+bc : " << to_binary((ieee754_parameter<float>::emask & bc), 32, false) << '\n';
-	std::cout << "fmask+bc : " << to_binary((ieee754_parameter<float>::fmask & bc), 32, false) << '\n';
+	std::cout << "smask    : " << to_binary(ieee754_parameter<float>::smask, false, 32) << '\n';
+	std::cout << "emask    : " << to_binary(ieee754_parameter<float>::emask, false, 32) << '\n';
+	std::cout << "fmask    : " << to_binary(ieee754_parameter<float>::fmask, false, 32) << '\n';
+	std::cout << "smask+bc : " << to_binary((ieee754_parameter<float>::smask & bc), false, 32) << '\n';
+	std::cout << "emask+bc : " << to_binary((ieee754_parameter<float>::emask & bc), false, 32) << '\n';
+	std::cout << "fmask+bc : " << to_binary((ieee754_parameter<float>::fmask & bc), false, 32) << '\n';
 //	uint32_t rawSignbits     = (ieee754_parameter<float>::smask & bc);
 	uint32_t rawExponentBits = (ieee754_parameter<float>::emask & bc) >> ieee754_parameter<float>::fbits;
 	uint32_t rawFractionBits = (ieee754_parameter<float>::fmask & bc);

static/native/float/nextafter.cpp

@@ -8,6 +8,7 @@
 #include <cmath>
 #include <concepts>
 #include <cfenv>
+#include <cfloat>
 #include <universal/verification/test_suite.hpp>
 
 // Regression testing guards: typically set by the cmake configuration, but MANUAL_TESTING is an override
@@ -73,11 +74,11 @@ try {
     {
         // #pragma STDC FENV_ACCESS ON
         std::feclearexcept(FE_ALL_EXCEPT);
-        double from4 = DBL_MAX, to4 = std::nextafter(from4, INFINITY);
+        double from = DBL_MAX, to = std::nextafter(from, INFINITY);
         std::cout << "The next representable double after " << std::setprecision(6)
-            << from4 << std::hexfloat << " (" << from4 << ')'
-            << std::defaultfloat << " is " << to4
-            << std::hexfloat << " (" << to4 << ")\n" << std::defaultfloat;
+            << from << std::hexfloat << " (" << from << ')'
+            << std::defaultfloat << " is " << to
+            << std::hexfloat << " (" << to << ")\n" << std::defaultfloat;
 
         if (std::fetestexcept(FE_OVERFLOW))
             std::cout << "   raised FE_OVERFLOW\n";