1 files changed, 108 insertions, 0 deletions
diff --git a/libc/test/src/math/ILogbTest.h b/libc/test/src/math/ILogbTest.h
new file mode 100644
index 000000000000..001b419de6cd
--- /dev/null
+++ b/libc/test/src/math/ILogbTest.h
@@ -0,0 +1,108 @@
+//===-- Utility class to test different flavors of ilogb --------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_TEST_SRC_MATH_ILOGBTEST_H
+#define LLVM_LIBC_TEST_SRC_MATH_ILOGBTEST_H
+
+#include "include/math.h"
+#include "utils/FPUtil/FPBits.h"
+#include "utils/FPUtil/ManipulationFunctions.h"
+#include "utils/UnitTest/Test.h"
+
+#include <limits.h>
+
+class ILogbTest : public __llvm_libc::testing::Test {
+public:
+  template <typename T> struct ILogbFunc { typedef int (*Func)(T); };
+
+  template <typename T>
+  void testSpecialNumbers(typename ILogbFunc<T>::Func func) {
+    EXPECT_EQ(FP_ILOGB0, func(__llvm_libc::fputil::FPBits<T>::zero()));
+    EXPECT_EQ(FP_ILOGB0, func(__llvm_libc::fputil::FPBits<T>::negZero()));
+
+    EXPECT_EQ(FP_ILOGBNAN, func(__llvm_libc::fputil::FPBits<T>::buildNaN(1)));
+
+    EXPECT_EQ(INT_MAX, func(__llvm_libc::fputil::FPBits<T>::inf()));
+    EXPECT_EQ(INT_MAX, func(__llvm_libc::fputil::FPBits<T>::negInf()));
+  }
+
+  template <typename T> void testPowersOfTwo(typename ILogbFunc<T>::Func func) {
+    EXPECT_EQ(0, func(T(1.0)));
+    EXPECT_EQ(0, func(T(-1.0)));
+
+    EXPECT_EQ(1, func(T(2.0)));
+    EXPECT_EQ(1, func(T(-2.0)));
+
+    EXPECT_EQ(2, func(T(4.0)));
+    EXPECT_EQ(2, func(T(-4.0)));
+
+    EXPECT_EQ(3, func(T(8.0)));
+    EXPECT_EQ(3, func(-8.0));
+
+    EXPECT_EQ(4, func(16.0));
+    EXPECT_EQ(4, func(-16.0));
+
+    EXPECT_EQ(5, func(32.0));
+    EXPECT_EQ(5, func(-32.0));
+  }
+
+  template <typename T>
+  void testSomeIntegers(typename ILogbFunc<T>::Func func) {
+    EXPECT_EQ(1, func(T(3.0)));
+    EXPECT_EQ(1, func(T(-3.0)));
+
+    EXPECT_EQ(2, func(T(7.0)));
+    EXPECT_EQ(2, func(T(-7.0)));
+
+    EXPECT_EQ(3, func(T(10.0)));
+    EXPECT_EQ(3, func(T(-10.0)));
+
+    EXPECT_EQ(4, func(T(31.0)));
+    EXPECT_EQ(4, func(-31.0));
+
+    EXPECT_EQ(5, func(55.0));
+    EXPECT_EQ(5, func(-55.0));
+  }
+
+  template <typename T>
+  void testSubnormalRange(typename ILogbFunc<T>::Func func) {
+    using FPBits = __llvm_libc::fputil::FPBits<T>;
+    using UIntType = typename FPBits::UIntType;
+    constexpr UIntType count = 1000001;
+    constexpr UIntType step =
+        (FPBits::maxSubnormal - FPBits::minSubnormal) / count;
+    for (UIntType v = FPBits::minSubnormal; v <= FPBits::maxSubnormal;
+         v += step) {
+      T x = FPBits(v);
+      if (isnan(x) || isinf(x) || x == 0.0)
+        continue;
+
+      int exponent;
+      __llvm_libc::fputil::frexp(x, exponent);
+      ASSERT_EQ(exponent, func(x) + 1);
+    }
+  }
+
+  template <typename T> void testNormalRange(typename ILogbFunc<T>::Func func) {
+    using FPBits = __llvm_libc::fputil::FPBits<T>;
+    using UIntType = typename FPBits::UIntType;
+    constexpr UIntType count = 1000001;
+    constexpr UIntType step = (FPBits::maxNormal - FPBits::minNormal) / count;
+    for (UIntType v = FPBits::minNormal; v <= FPBits::maxNormal; v += step) {
+      T x = FPBits(v);
+      if (isnan(x) || isinf(x) || x == 0.0)
+        continue;
+
+      int exponent;
+      __llvm_libc::fputil::frexp(x, exponent);
+      ASSERT_EQ(exponent, func(x) + 1);
+    }
+  }
+};
+
+#endif // LLVM_LIBC_TEST_SRC_MATH_ILOGBTEST_H