Abseil Common Libraries (C++) (grcp 依赖)
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55 lines
2.0 KiB
55 lines
2.0 KiB
// Copyright 2022 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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#ifndef ABSL_BASE_INTERNAL_CYCLECLOCK_CONFIG_H_ |
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#define ABSL_BASE_INTERNAL_CYCLECLOCK_CONFIG_H_ |
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#include <cstdint> |
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#include "absl/base/config.h" |
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#include "absl/base/internal/inline_variable.h" |
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#include "absl/base/internal/unscaledcycleclock_config.h" |
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namespace absl { |
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ABSL_NAMESPACE_BEGIN |
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namespace base_internal { |
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#if ABSL_USE_UNSCALED_CYCLECLOCK |
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#ifdef NDEBUG |
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#ifdef ABSL_INTERNAL_UNSCALED_CYCLECLOCK_FREQUENCY_IS_CPU_FREQUENCY |
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// Not debug mode and the UnscaledCycleClock frequency is the CPU |
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// frequency. Scale the CycleClock to prevent overflow if someone |
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// tries to represent the time as cycles since the Unix epoch. |
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ABSL_INTERNAL_INLINE_CONSTEXPR(int32_t, kCycleClockShift, 1); |
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#else |
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// Not debug mode and the UnscaledCycleClock isn't operating at the |
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// raw CPU frequency. There is no need to do any scaling, so don't |
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// needlessly sacrifice precision. |
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ABSL_INTERNAL_INLINE_CONSTEXPR(int32_t, kCycleClockShift, 0); |
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#endif |
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#else // NDEBUG |
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// In debug mode use a different shift to discourage depending on a |
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// particular shift value. |
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ABSL_INTERNAL_INLINE_CONSTEXPR(int32_t, kCycleClockShift, 2); |
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#endif // NDEBUG |
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ABSL_INTERNAL_INLINE_CONSTEXPR(double, kCycleClockFrequencyScale, |
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1.0 / (1 << kCycleClockShift)); |
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#endif // ABSL_USE_UNSCALED_CYCLECLOC |
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} // namespace base_internal |
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ABSL_NAMESPACE_END |
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} // namespace absl |
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#endif // ABSL_BASE_INTERNAL_CYCLECLOCK_CONFIG_H_
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