Abseil Common Libraries (C++) (grcp 依赖)
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56 lines
2.0 KiB
56 lines
2.0 KiB
2 years ago
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// 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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