110 lines
3.4 KiB
C++
110 lines
3.4 KiB
C++
// Copyright 2017 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Unit test for bit_cast template.
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#include <cstdint>
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#include <cstring>
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#include "gtest/gtest.h"
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#include "absl/base/casts.h"
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#include "absl/base/macros.h"
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namespace absl {
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ABSL_NAMESPACE_BEGIN
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namespace {
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template <int N>
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struct marshall { char buf[N]; };
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template <typename T>
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void TestMarshall(const T values[], int num_values) {
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for (int i = 0; i < num_values; ++i) {
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T t0 = values[i];
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marshall<sizeof(T)> m0 = absl::bit_cast<marshall<sizeof(T)> >(t0);
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T t1 = absl::bit_cast<T>(m0);
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marshall<sizeof(T)> m1 = absl::bit_cast<marshall<sizeof(T)> >(t1);
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ASSERT_EQ(0, memcmp(&t0, &t1, sizeof(T)));
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ASSERT_EQ(0, memcmp(&m0, &m1, sizeof(T)));
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}
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}
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// Convert back and forth to an integral type. The C++ standard does
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// not guarantee this will work, but we test that this works on all the
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// platforms we support.
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//
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// Likewise, we below make assumptions about sizeof(float) and
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// sizeof(double) which the standard does not guarantee, but which hold on the
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// platforms we support.
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template <typename T, typename I>
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void TestIntegral(const T values[], int num_values) {
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for (int i = 0; i < num_values; ++i) {
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T t0 = values[i];
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I i0 = absl::bit_cast<I>(t0);
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T t1 = absl::bit_cast<T>(i0);
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I i1 = absl::bit_cast<I>(t1);
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ASSERT_EQ(0, memcmp(&t0, &t1, sizeof(T)));
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ASSERT_EQ(i0, i1);
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}
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}
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TEST(BitCast, Bool) {
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static const bool bool_list[] = { false, true };
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TestMarshall<bool>(bool_list, ABSL_ARRAYSIZE(bool_list));
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}
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TEST(BitCast, Int32) {
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static const int32_t int_list[] =
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{ 0, 1, 100, 2147483647, -1, -100, -2147483647, -2147483647-1 };
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TestMarshall<int32_t>(int_list, ABSL_ARRAYSIZE(int_list));
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}
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TEST(BitCast, Int64) {
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static const int64_t int64_list[] =
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{ 0, 1, 1LL << 40, -1, -(1LL<<40) };
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TestMarshall<int64_t>(int64_list, ABSL_ARRAYSIZE(int64_list));
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}
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TEST(BitCast, Uint64) {
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static const uint64_t uint64_list[] =
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{ 0, 1, 1LLU << 40, 1LLU << 63 };
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TestMarshall<uint64_t>(uint64_list, ABSL_ARRAYSIZE(uint64_list));
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}
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TEST(BitCast, Float) {
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static const float float_list[] =
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{ 0.0f, 1.0f, -1.0f, 10.0f, -10.0f,
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1e10f, 1e20f, 1e-10f, 1e-20f,
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2.71828f, 3.14159f };
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TestMarshall<float>(float_list, ABSL_ARRAYSIZE(float_list));
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TestIntegral<float, int>(float_list, ABSL_ARRAYSIZE(float_list));
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TestIntegral<float, unsigned>(float_list, ABSL_ARRAYSIZE(float_list));
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}
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TEST(BitCast, Double) {
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static const double double_list[] =
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{ 0.0, 1.0, -1.0, 10.0, -10.0,
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1e10, 1e100, 1e-10, 1e-100,
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2.718281828459045,
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3.141592653589793238462643383279502884197169399375105820974944 };
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TestMarshall<double>(double_list, ABSL_ARRAYSIZE(double_list));
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TestIntegral<double, int64_t>(double_list, ABSL_ARRAYSIZE(double_list));
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TestIntegral<double, uint64_t>(double_list, ABSL_ARRAYSIZE(double_list));
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}
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} // namespace
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ABSL_NAMESPACE_END
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} // namespace absl
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