libc/test/src/stdfix/SqrtTest.h

   1 //===-- Utility class to test fixed-point sqrt ------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "test/UnitTest/Test.h"
  10
  11 #include "src/__support/CPP/bit.h"
  12 #include "src/__support/FPUtil/BasicOperations.h"
  13 #include "src/__support/FPUtil/sqrt.h"
  14 #include "src/__support/fixed_point/fx_rep.h"
  15 #include "src/__support/fixed_point/sqrt.h"
  16
  17 template <typename T> class SqrtTest : public LIBC_NAMESPACE::testing::Test {
  18
  19   using FXRep = LIBC_NAMESPACE::fixed_point::FXRep<T>;
  20   static constexpr T zero = FXRep::ZERO();
  21   static constexpr T min = FXRep::MIN();
  22   static constexpr T max = FXRep::MAX();
  23   static constexpr T half = static_cast<T>(0.5);
  24   static constexpr T quarter = static_cast<T>(0.25);
  25   static constexpr T one =
  26       (FXRep::INTEGRAL_LEN > 0) ? static_cast<T>(1) : FXRep::MAX();
  27   static constexpr T eps = FXRep::EPS();
  28
  29 public:
  30   typedef T (*SqrtFunc)(T);
  31
  32   void testSpecialNumbers(SqrtFunc func) {
  33     EXPECT_EQ(zero, func(zero));
  34     EXPECT_EQ(half, func(quarter));
  35
  36     if constexpr (FXRep::INTEGRAL_LEN) {
  37       EXPECT_EQ(one, func(one));
  38       EXPECT_EQ(static_cast<T>(2.0), func(static_cast<T>(4.0)));
  39     }
  40
  41     using StorageType = typename FXRep::StorageType;
  42
  43     constexpr size_t COUNT = 255;
  44     constexpr StorageType STEP =
  45         StorageType(~StorageType(0)) / static_cast<StorageType>(COUNT);
  46     constexpr double ERR = 3.0 * static_cast<double>(eps);
  47     StorageType x = 0;
  48     for (size_t i = 0; i < COUNT; ++i, x += STEP) {
  49       T v = LIBC_NAMESPACE::cpp::bit_cast<T>(x);
  50       double v_d = static_cast<double>(v);
  51       double errors = LIBC_NAMESPACE::fputil::abs(
  52           static_cast<double>(func(v)) -
  53           LIBC_NAMESPACE::fputil::sqrt<double>(v_d));
  54       if (errors > ERR) {
  55         // Print out the failure input and output.
  56         EXPECT_EQ(v, zero);
  57         EXPECT_EQ(func(v), zero);
  58       }
  59       ASSERT_TRUE(errors <= ERR);
  60     }
  61   }
  62 };
  63
  64 #define LIST_SQRT_TESTS(T, func)                                               \
  65   using LlvmLibcSqrtTest = SqrtTest<T>;                                        \
  66   TEST_F(LlvmLibcSqrtTest, SpecialNumbers) { testSpecialNumbers(&func); }      \
  67   static_assert(true, "Require semicolon.")