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 ABSL_NAMESPACE_BEGIN
26 namespace {
27
28 template <int N>
29 struct marshall { char buf[N]; };
30
31 template <typename T>
TestMarshall(const T values[],int num_values)32 void TestMarshall(const T values[], int num_values) {
33 for (int i = 0; i < num_values; ++i) {
34 T t0 = values[i];
35 marshall<sizeof(T)> m0 = absl::bit_cast<marshall<sizeof(T)> >(t0);
36 T t1 = absl::bit_cast<T>(m0);
37 marshall<sizeof(T)> m1 = absl::bit_cast<marshall<sizeof(T)> >(t1);
38 ASSERT_EQ(0, memcmp(&t0, &t1, sizeof(T)));
39 ASSERT_EQ(0, memcmp(&m0, &m1, sizeof(T)));
40 }
41 }
42
43 // Convert back and forth to an integral type. The C++ standard does
44 // not guarantee this will work, but we test that this works on all the
45 // platforms we support.
46 //
47 // Likewise, we below make assumptions about sizeof(float) and
48 // sizeof(double) which the standard does not guarantee, but which hold on the
49 // platforms we support.
50
51 template <typename T, typename I>
TestIntegral(const T values[],int num_values)52 void TestIntegral(const T values[], int num_values) {
53 for (int i = 0; i < num_values; ++i) {
54 T t0 = values[i];
55 I i0 = absl::bit_cast<I>(t0);
56 T t1 = absl::bit_cast<T>(i0);
57 I i1 = absl::bit_cast<I>(t1);
58 ASSERT_EQ(0, memcmp(&t0, &t1, sizeof(T)));
59 ASSERT_EQ(i0, i1);
60 }
61 }
62
TEST(BitCast,Bool)63 TEST(BitCast, Bool) {
64 static const bool bool_list[] = { false, true };
65 TestMarshall<bool>(bool_list, ABSL_ARRAYSIZE(bool_list));
66 }
67
TEST(BitCast,Int32)68 TEST(BitCast, Int32) {
69 static const int32_t int_list[] =
70 { 0, 1, 100, 2147483647, -1, -100, -2147483647, -2147483647-1 };
71 TestMarshall<int32_t>(int_list, ABSL_ARRAYSIZE(int_list));
72 }
73
TEST(BitCast,Int64)74 TEST(BitCast, Int64) {
75 static const int64_t int64_list[] =
76 { 0, 1, 1LL << 40, -1, -(1LL<<40) };
77 TestMarshall<int64_t>(int64_list, ABSL_ARRAYSIZE(int64_list));
78 }
79
TEST(BitCast,Uint64)80 TEST(BitCast, Uint64) {
81 static const uint64_t uint64_list[] =
82 { 0, 1, 1LLU << 40, 1LLU << 63 };
83 TestMarshall<uint64_t>(uint64_list, ABSL_ARRAYSIZE(uint64_list));
84 }
85
TEST(BitCast,Float)86 TEST(BitCast, Float) {
87 static const float float_list[] =
88 { 0.0f, 1.0f, -1.0f, 10.0f, -10.0f,
89 1e10f, 1e20f, 1e-10f, 1e-20f,
90 2.71828f, 3.14159f };
91 TestMarshall<float>(float_list, ABSL_ARRAYSIZE(float_list));
92 TestIntegral<float, int>(float_list, ABSL_ARRAYSIZE(float_list));
93 TestIntegral<float, unsigned>(float_list, ABSL_ARRAYSIZE(float_list));
94 }
95
TEST(BitCast,Double)96 TEST(BitCast, Double) {
97 static const double double_list[] =
98 { 0.0, 1.0, -1.0, 10.0, -10.0,
99 1e10, 1e100, 1e-10, 1e-100,
100 2.718281828459045,
101 3.141592653589793238462643383279502884197169399375105820974944 };
102 TestMarshall<double>(double_list, ABSL_ARRAYSIZE(double_list));
103 TestIntegral<double, int64_t>(double_list, ABSL_ARRAYSIZE(double_list));
104 TestIntegral<double, uint64_t>(double_list, ABSL_ARRAYSIZE(double_list));
105 }
106
107 } // namespace
108 ABSL_NAMESPACE_END
109 } // namespace absl
110