bit_cast_test.cc
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1 // Copyright 2017 The Abseil Authors.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // https://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14 
15 // Unit test for bit_cast template.
16 
17 #include <cstdint>
18 #include <cstring>
19 
20 #include "gtest/gtest.h"
21 #include "absl/base/casts.h"
22 #include "absl/base/macros.h"
23 
24 namespace absl {
25 namespace {
26 
27 template <int N>
28 struct marshall { char buf[N]; };
29 
30 template <typename T>
31 void TestMarshall(const T values[], int num_values) {
32  for (int i = 0; i < num_values; ++i) {
33  T t0 = values[i];
34  marshall<sizeof(T)> m0 = absl::bit_cast<marshall<sizeof(T)> >(t0);
35  T t1 = absl::bit_cast<T>(m0);
36  marshall<sizeof(T)> m1 = absl::bit_cast<marshall<sizeof(T)> >(t1);
37  ASSERT_EQ(0, memcmp(&t0, &t1, sizeof(T)));
38  ASSERT_EQ(0, memcmp(&m0, &m1, sizeof(T)));
39  }
40 }
41 
42 // Convert back and forth to an integral type. The C++ standard does
43 // not guarantee this will work, but we test that this works on all the
44 // platforms we support.
45 //
46 // Likewise, we below make assumptions about sizeof(float) and
47 // sizeof(double) which the standard does not guarantee, but which hold on the
48 // platforms we support.
49 
50 template <typename T, typename I>
51 void TestIntegral(const T values[], int num_values) {
52  for (int i = 0; i < num_values; ++i) {
53  T t0 = values[i];
54  I i0 = absl::bit_cast<I>(t0);
55  T t1 = absl::bit_cast<T>(i0);
56  I i1 = absl::bit_cast<I>(t1);
57  ASSERT_EQ(0, memcmp(&t0, &t1, sizeof(T)));
58  ASSERT_EQ(i0, i1);
59  }
60 }
61 
62 TEST(BitCast, Bool) {
63  static const bool bool_list[] = { false, true };
64  TestMarshall<bool>(bool_list, ABSL_ARRAYSIZE(bool_list));
65 }
66 
67 TEST(BitCast, Int32) {
68  static const int32_t int_list[] =
69  { 0, 1, 100, 2147483647, -1, -100, -2147483647, -2147483647-1 };
70  TestMarshall<int32_t>(int_list, ABSL_ARRAYSIZE(int_list));
71 }
72 
73 TEST(BitCast, Int64) {
74  static const int64_t int64_list[] =
75  { 0, 1, 1LL << 40, -1, -(1LL<<40) };
76  TestMarshall<int64_t>(int64_list, ABSL_ARRAYSIZE(int64_list));
77 }
78 
79 TEST(BitCast, Uint64) {
80  static const uint64_t uint64_list[] =
81  { 0, 1, 1LLU << 40, 1LLU << 63 };
82  TestMarshall<uint64_t>(uint64_list, ABSL_ARRAYSIZE(uint64_list));
83 }
84 
85 TEST(BitCast, Float) {
86  static const float float_list[] =
87  { 0.0f, 1.0f, -1.0f, 10.0f, -10.0f,
88  1e10f, 1e20f, 1e-10f, 1e-20f,
89  2.71828f, 3.14159f };
90  TestMarshall<float>(float_list, ABSL_ARRAYSIZE(float_list));
91  TestIntegral<float, int>(float_list, ABSL_ARRAYSIZE(float_list));
92  TestIntegral<float, unsigned>(float_list, ABSL_ARRAYSIZE(float_list));
93 }
94 
95 TEST(BitCast, Double) {
96  static const double double_list[] =
97  { 0.0, 1.0, -1.0, 10.0, -10.0,
98  1e10, 1e100, 1e-10, 1e-100,
99  2.718281828459045,
100  3.141592653589793238462643383279502884197169399375105820974944 };
101  TestMarshall<double>(double_list, ABSL_ARRAYSIZE(double_list));
102  TestIntegral<double, int64_t>(double_list, ABSL_ARRAYSIZE(double_list));
103  TestIntegral<double, uint64_t>(double_list, ABSL_ARRAYSIZE(double_list));
104 }
105 
106 } // namespace
107 } // namespace absl
TEST(NotificationTest, SanityTest)
Dest bit_cast(const Source &source)
Definition: casts.h:154
char buf[N]
Definition: algorithm.h:29
#define ABSL_ARRAYSIZE(array)
Definition: macros.h:42


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autogenerated on Mon Feb 28 2022 21:31:17