src/dawn/utils/WindowsTimer.cpp

// Copyright 2019 The Dawn & Tint Authors
//
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// modification, are permitted provided that the following conditions are met:
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//    list of conditions and the following disclaimer.
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//    this list of conditions and the following disclaimer in the documentation
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//    this software without specific prior written permission.
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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#include <windows.h>

#include "dawn/utils/Timer.h"

namespace dawn::utils {

class WindowsTimer : public Timer {
  public:
    WindowsTimer() : Timer(), mRunning(false), mFrequency(0) {}

    ~WindowsTimer() override = default;

    void Start() override {
        LARGE_INTEGER curTime;
        QueryPerformanceCounter(&curTime);
        mStartTime = curTime.QuadPart;

        // Cache the frequency
        GetFrequency();

        mRunning = true;
    }

    void Stop() override {
        LARGE_INTEGER curTime;
        QueryPerformanceCounter(&curTime);
        mStopTime = curTime.QuadPart;

        mRunning = false;
    }

    double GetElapsedTime() const override {
        LONGLONG endTime;
        if (mRunning) {
            LARGE_INTEGER curTime;
            QueryPerformanceCounter(&curTime);
            endTime = curTime.QuadPart;
        } else {
            endTime = mStopTime;
        }

        return static_cast<double>(endTime - mStartTime) / mFrequency;
    }

    double GetAbsoluteTime() override {
        LARGE_INTEGER curTime;
        QueryPerformanceCounter(&curTime);

        return static_cast<double>(curTime.QuadPart) / GetFrequency();
    }

  private:
    LONGLONG GetFrequency() {
        if (mFrequency == 0) {
            LARGE_INTEGER frequency = {};
            QueryPerformanceFrequency(&frequency);

            mFrequency = frequency.QuadPart;
        }

        return mFrequency;
    }

    bool mRunning;
    LONGLONG mStartTime;
    LONGLONG mStopTime;
    LONGLONG mFrequency;
};

Timer* CreateTimer() {
    return new WindowsTimer();
}

}  // namespace dawn::utils