|
|
|
|
// Copyright 2017 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.
|
|
|
|
|
|
|
|
|
|
// The implementation of CycleClock::Frequency.
|
|
|
|
|
//
|
|
|
|
|
// NOTE: only i386 and x86_64 have been well tested.
|
|
|
|
|
// PPC, sparc, alpha, and ia64 are based on
|
|
|
|
|
// http://peter.kuscsik.com/wordpress/?p=14
|
|
|
|
|
// with modifications by m3b. See also
|
|
|
|
|
// https://setisvn.ssl.berkeley.edu/svn/lib/fftw-3.0.1/kernel/cycle.h
|
|
|
|
|
|
|
|
|
|
#include "absl/base/internal/cycleclock.h"
|
|
|
|
|
|
|
|
|
|
#include <atomic>
|
|
|
|
|
#include <chrono> // NOLINT(build/c++11)
|
|
|
|
|
|
|
|
|
|
#include "absl/base/attributes.h"
|
|
|
|
|
#include "absl/base/internal/unscaledcycleclock.h"
|
|
|
|
|
|
|
|
|
|
namespace absl {
|
|
|
|
|
ABSL_NAMESPACE_BEGIN
|
|
|
|
|
namespace base_internal {
|
|
|
|
|
|
|
|
|
|
#if ABSL_USE_UNSCALED_CYCLECLOCK
|
|
|
|
|
|
|
|
|
|
constexpr int32_t CycleClock::kShift;
|
|
|
|
|
constexpr double CycleClock::kFrequencyScale;
|
|
|
|
|
|
|
|
|
|
ABSL_CONST_INIT std::atomic<CycleClockSourceFunc>
|
|
|
|
|
CycleClock::cycle_clock_source_{nullptr};
|
|
|
|
|
|
|
|
|
|
void CycleClockSource::Register(CycleClockSourceFunc source) {
|
|
|
|
|
// Corresponds to the load(std::memory_order_acquire) in LoadCycleClockSource.
|
|
|
|
|
CycleClock::cycle_clock_source_.store(source, std::memory_order_release);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
#ifdef _WIN32
|
|
|
|
|
int64_t CycleClock::Now() {
|
|
|
|
|
auto fn = LoadCycleClockSource();
|
|
|
|
|
if (fn == nullptr) {
|
|
|
|
|
return base_internal::UnscaledCycleClock::Now() >> kShift;
|
|
|
|
|
}
|
|
|
|
|
return fn() >> kShift;
|
|
|
|
|
}
|
|
|
|
|
#endif
|
|
|
|
|
|
|
|
|
|
#else
|
|
|
|
|
|
|
|
|
|
int64_t CycleClock::Now() {
|
|
|
|
|
return std::chrono::duration_cast<std::chrono::nanoseconds>(
|
|
|
|
|
std::chrono::steady_clock::now().time_since_epoch())
|
|
|
|
|
.count();
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
double CycleClock::Frequency() {
|
|
|
|
|
return 1e9;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
#endif
|
|
|
|
|
|
|
|
|
|
} // namespace base_internal
|
|
|
|
|
ABSL_NAMESPACE_END
|
|
|
|
|
} // namespace absl
|
