Implement copysign

Rinzii · Mar 13, 2024 · 33a63d1 · 33a63d1
1 parent 840a6b1
commit 33a63d1
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diff --git a/include/ccmath/detail/fmanip/copysign.hpp b/include/ccmath/detail/fmanip/copysign.hpp
@@ -8,7 +8,36 @@
 
 #pragma once
 
+#include "ccmath/internal/helpers/bits.hpp"
+#include "ccmath/detail/compare/signbit.hpp"
+#include "ccmath/detail/compare/isnan.hpp"
+#include "ccmath/detail/basic/abs.hpp"
+
 namespace ccm
 {
+	namespace
+    {
+        namespace impl
+        {
+            template <typename T>
+            inline constexpr T copysign_impl(T x, T y)
+            {
+				if (ccm::isnan(x) || ccm::isnan(y))
+                {
+                    if (ccm::signbit(y)) { return -std::numeric_limits<T>::quiet_NaN(); }
+					else { return std::numeric_limits<T>::quiet_NaN(); }
+                }
+
+				int sign_bit = ccm::signbit(y) ? -1 : 1;
+				return ccm::abs(x) * sign_bit;
+            }
+        } // namespace impl
+    }	  // namespace
+
+    template <typename T>
+    inline constexpr T copysign(T x, T y)
+    {
+        return impl::copysign_impl(x, y);
+    }
 
 } // namespace ccm
diff --git a/test/fmanip/copysign_test.cpp b/test/fmanip/copysign_test.cpp
@@ -14,6 +14,17 @@
 
 TEST(CcmathFmanipTests, Copysign)
 {
+	EXPECT_EQ(ccm::copysign(1.0, +2.0), std::copysign(1.0, +2.0));
+	EXPECT_EQ(ccm::copysign(1.0, -2.0), std::copysign(1.0, -2.0));
+	EXPECT_EQ(ccm::copysign(std::numeric_limits<double>::infinity(), -2.0), std::copysign(std::numeric_limits<double>::infinity(), -2.0));
 
+	bool isCcmCopysignNan = std::isnan(ccm::copysign(std::numeric_limits<double>::quiet_NaN(), -2.0));
+	bool isStdCopysignNan = std::isnan(std::copysign(std::numeric_limits<double>::quiet_NaN(), -2.0));
+	bool isCcmCopysignNanNegative = std::signbit(ccm::copysign(std::numeric_limits<double>::quiet_NaN(), -2.0));
+	bool isStdCopysignNanNegative = std::signbit(std::copysign(std::numeric_limits<double>::quiet_NaN(), -2.0));
+	EXPECT_EQ(isCcmCopysignNan, isStdCopysignNan);
+	EXPECT_EQ(isCcmCopysignNanNegative, isStdCopysignNanNegative);
+
+	// TODO: Add more tests
 }