test/src/math/LogbTest.h

//===-- Utility class to test logb[f|l] -------------------------*- 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
//
//===----------------------------------------------------------------------===//

#include "utils/FPUtil/ManipulationFunctions.h"
#include "utils/FPUtil/TestHelpers.h"
#include "utils/MPFRWrapper/MPFRUtils.h"
#include "utils/UnitTest/Test.h"

#include <math.h>

namespace mpfr = __llvm_libc::testing::mpfr;

template <typename T> class LogbTest : public __llvm_libc::testing::Test {

  DECLARE_SPECIAL_CONSTANTS(T)

  static constexpr UIntType HiddenBit =
      UIntType(1) << __llvm_libc::fputil::MantissaWidth<T>::value;

public:
  typedef T (*LogbFunc)(T);

  void testSpecialNumbers(LogbFunc func) {
    ASSERT_FP_EQ(aNaN, func(aNaN));
    ASSERT_FP_EQ(inf, func(inf));
    ASSERT_FP_EQ(inf, func(negInf));
    ASSERT_FP_EQ(negInf, func(0.0));
    ASSERT_FP_EQ(negInf, func(-0.0));
  }

  void testPowersOfTwo(LogbFunc func) {
    EXPECT_FP_EQ(T(0.0), func(T(1.0)));
    EXPECT_FP_EQ(T(0.0), func(T(-1.0)));

    EXPECT_FP_EQ(T(1.0), func(T(2.0)));
    EXPECT_FP_EQ(T(1.0), func(T(-2.0)));

    EXPECT_FP_EQ(T(2.0), func(T(4.0)));
    EXPECT_FP_EQ(T(2.0), func(T(-4.0)));

    EXPECT_FP_EQ(T(3.0), func(T(8.0)));
    EXPECT_FP_EQ(T(3.0), func(T(-8.0)));

    EXPECT_FP_EQ(T(4.0), func(T(16.0)));
    EXPECT_FP_EQ(T(4.0), func(T(-16.0)));

    EXPECT_FP_EQ(T(5.0), func(T(32.0)));
    EXPECT_FP_EQ(T(5.0), func(T(-32.0)));
  }

  void testSomeIntegers(LogbFunc func) {
    EXPECT_FP_EQ(T(1.0), func(T(3.0)));
    EXPECT_FP_EQ(T(1.0), func(T(-3.0)));

    EXPECT_FP_EQ(T(2.0), func(T(7.0)));
    EXPECT_FP_EQ(T(2.0), func(T(-7.0)));

    EXPECT_FP_EQ(T(3.0), func(T(10.0)));
    EXPECT_FP_EQ(T(3.0), func(T(-10.0)));

    EXPECT_FP_EQ(T(4.0), func(T(31.0)));
    EXPECT_FP_EQ(T(4.0), func(T(-31.0)));

    EXPECT_FP_EQ(T(5.0), func(T(55.0)));
    EXPECT_FP_EQ(T(5.0), func(T(-55.0)));
  }

  void testRange(LogbFunc func) {
    using UIntType = typename FPBits::UIntType;
    constexpr UIntType count = 10000000;
    constexpr UIntType step = UIntType(-1) / count;
    for (UIntType i = 0, v = 0; i <= count; ++i, v += step) {
      T x = static_cast<T>(FPBits(v));
      if (isnan(x) || isinf(x) || x == 0.0l)
        continue;

      int exponent;
      __llvm_libc::fputil::frexp(x, exponent);
      ASSERT_FP_EQ(T(exponent), func(x) + T(1.0));
    }
  }
};

#define LIST_LOGB_TESTS(T, func)                                               \
  using LlvmLibcLogbTest = LogbTest<T>;                                        \
  TEST_F(LlvmLibcLogbTest, SpecialNumbers) { testSpecialNumbers(&func); }      \
  TEST_F(LlvmLibcLogbTest, PowersOfTwo) { testPowersOfTwo(&func); }            \
  TEST_F(LlvmLibcLogbTest, SomeIntegers) { testSomeIntegers(&func); }          \
  TEST_F(LlvmLibcLogbTest, InRange) { testRange(&func); }