timer.h

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/*
    TIMER.H
    -------
    Copyright (c) 2017 Andrew Trotman
    Released under the 2-clause BSD license (See:https://en.wikipedia.org/wiki/BSD_licenses)
*/
#pragma once

#include <stdio.h>
#include <stdint.h>

#include <chrono>
#include <thread>

#include "asserts.h"

namespace JASS
    {
    /*
        CLASS TIMER
        -----------
    */
    class timer
        {
        private:
            /*
                TYPEDEF TIMER::STOP_WATCH
                -------------------------
            */
            typedef std::chrono::time_point<std::chrono::steady_clock, std::chrono::nanoseconds> stop_watch;

            /*
                CLASS TIMER::DURATION
                ----------------------
            */
            class duration
                {
                private:
                    std::chrono::nanoseconds took;          

                public:
                    /*
                        TIMER::DURATION::DURATION()
                        ---------------------------
                    */
                    duration(std::chrono::nanoseconds value)
                        {
                        took = value;
                        }

                    /*
                        TIMER::DURATION::MILLISECONDS()
                        -------------------------------
                    */
                    auto milliseconds(void)
                        {
                        return std::chrono::duration_cast<std::chrono::milliseconds>(took).count();
                        }

                    /*
                        TIMER::DURATION::MICROSECONDS()
                        -------------------------------
                    */
                    auto microseconds(void)
                        {
                        return std::chrono::duration_cast<std::chrono::microseconds>(took).count();
                        }

                    /*
                        TIMER::DURATION::NANOSECONDS()
                        ------------------------------
                    */
                    auto nanoseconds(void)
                        {
                        return std::chrono::duration_cast<std::chrono::nanoseconds>(took).count();
                        }
                };

        public:
            /*
                TIMER::START()
                --------------
            */
            static stop_watch start()
                {
                return std::chrono::steady_clock::now();
                }

            /*
                TIMER::STOP()
                -------------
            */
            static duration stop(stop_watch watch)
                {
                return std::chrono::steady_clock::now() - watch;
                }

            /*
                TIMER::UNITTEST()
                -----------------
            */
            static void unittest(void)
                {
                /*
                    Time about 100 milliseconds
                */
                auto clock = timer::start();
                std::this_thread::sleep_for (std::chrono::milliseconds(100));
                auto took = timer::stop(clock);

                /*
                    Get the actual time in different units
                */
                size_t nano = took.nanoseconds();
                size_t micro = took.microseconds();
                size_t milli = took.milliseconds();

                /*
                    Check that the timer took about the same time in nanoseconds as microseconds
                */
                size_t nano_as_micro = nano / 1000;
                JASS_assert((nano_as_micro >= micro - 1) && (nano_as_micro - 1 <= micro));

                /*
                    Check that the timer took about the same time in nanoseconds as milliseconds
                */
                size_t nano_as_milli = nano / 1000'000;
                JASS_assert((nano_as_milli >= milli - 1) && (nano_as_milli - 1 <= milli));

                /*
                    Yay!
                */
                puts("timer::PASSED");
                }

        };
    }