// Copyright 2022 The Abseil Authors // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // https://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. #ifndef ABSL_BASE_INTERNAL_CYCLECLOCK_CONFIG_H_ #define ABSL_BASE_INTERNAL_CYCLECLOCK_CONFIG_H_ #include <cstdint> #include "absl/base/config.h" #include "absl/base/internal/inline_variable.h" #include "absl/base/internal/unscaledcycleclock_config.h" namespace absl { ABSL_NAMESPACE_BEGIN namespace base_internal { #if ABSL_USE_UNSCALED_CYCLECLOCK #ifdef NDEBUG #ifdef ABSL_INTERNAL_UNSCALED_CYCLECLOCK_FREQUENCY_IS_CPU_FREQUENCY // Not debug mode and the UnscaledCycleClock frequency is the CPU // frequency. Scale the CycleClock to prevent overflow if someone // tries to represent the time as cycles since the Unix epoch. ABSL_INTERNAL_INLINE_CONSTEXPR(int32_t, kCycleClockShift, 1); #else // Not debug mode and the UnscaledCycleClock isn't operating at the // raw CPU frequency. There is no need to do any scaling, so don't // needlessly sacrifice precision. ABSL_INTERNAL_INLINE_CONSTEXPR(int32_t, kCycleClockShift, 0); #endif #else // NDEBUG // In debug mode use a different shift to discourage depending on a // particular shift value. ABSL_INTERNAL_INLINE_CONSTEXPR(int32_t, kCycleClockShift, 2); #endif // NDEBUG ABSL_INTERNAL_INLINE_CONSTEXPR(double, kCycleClockFrequencyScale, 1.0 / (1 << kCycleClockShift)); #endif // ABSL_USE_UNSCALED_CYCLECLOC } // namespace base_internal ABSL_NAMESPACE_END } // namespace absl #endif // ABSL_BASE_INTERNAL_CYCLECLOCK_CONFIG_H_