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** Copyright (C) 2016 The Qt Company Ltd.
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** General Public License version 3 as published by the Free Software
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** ensure the GNU Lesser General Public License version 3 requirements
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// ask for the latest POSIX, just in case
#define _POSIX_C_SOURCE 200809L

#include "qelapsedtimer.h"
#include "qdeadlinetimer.h"
#include "qdeadlinetimer_p.h"
#include <sys/time.h>
#include <time.h>
#include <unistd.h>

#include <mach/mach_time.h>
#include <private/qcore_unix_p.h>

QT_BEGIN_NAMESPACE

#ifdef __LP64__
typedef __int128_t LargeInt;
#else
typedef qint64 LargeInt;
#endif

QElapsedTimer::ClockType QElapsedTimer::clockType() noexcept
{
    return MachAbsoluteTime;
}

bool QElapsedTimer::isMonotonic() noexcept
{
    return true;
}

static mach_timebase_info_data_t info = { 0, 0 };
static qint64 absoluteToNSecs(qint64 cpuTime)
{
    if (info.denom == 0)
        mach_timebase_info(&info);

    // don't do multiplication & division if those are equal
    // (mathematically it would be the same, but it's computationally expensive)
    if (info.numer == info.denom)
        return cpuTime;
    qint64 nsecs = LargeInt(cpuTime) * info.numer / info.denom;
    return nsecs;
}

static qint64 absoluteToMSecs(qint64 cpuTime)
{
    return absoluteToNSecs(cpuTime) / 1000000;
}

timespec qt_gettime() noexcept
{
    timespec tv;

    uint64_t cpu_time = mach_absolute_time();
    uint64_t nsecs = absoluteToNSecs(cpu_time);
    tv.tv_sec = nsecs / 1000000000ull;
    tv.tv_nsec = nsecs - (tv.tv_sec * 1000000000ull);
    return tv;
}

void qt_nanosleep(timespec amount)
{
    // Mac doesn't have clock_nanosleep, but it does have nanosleep.
    // nanosleep is POSIX.1-1993

    int r;
    EINTR_LOOP(r, nanosleep(&amount, &amount));
}

void QElapsedTimer::start() noexcept
{
    t1 = mach_absolute_time();
    t2 = 0;
}

qint64 QElapsedTimer::restart() noexcept
{
    qint64 old = t1;
    t1 = mach_absolute_time();
    t2 = 0;

    return absoluteToMSecs(t1 - old);
}

qint64 QElapsedTimer::nsecsElapsed() const noexcept
{
    uint64_t cpu_time = mach_absolute_time();
    return absoluteToNSecs(cpu_time - t1);
}

qint64 QElapsedTimer::elapsed() const noexcept
{
    uint64_t cpu_time = mach_absolute_time();
    return absoluteToMSecs(cpu_time - t1);
}

qint64 QElapsedTimer::msecsSinceReference() const noexcept
{
    return absoluteToMSecs(t1);
}

qint64 QElapsedTimer::msecsTo(const QElapsedTimer &other) const noexcept
{
    return absoluteToMSecs(other.t1 - t1);
}

qint64 QElapsedTimer::secsTo(const QElapsedTimer &other) const noexcept
{
    return msecsTo(other) / 1000;
}

bool operator<(const QElapsedTimer &v1, const QElapsedTimer &v2) noexcept
{
    return v1.t1 < v2.t1;
}

QDeadlineTimer QDeadlineTimer::current(Qt::TimerType timerType) noexcept
{
    static_assert(!QDeadlineTimerNanosecondsInT2);
    QDeadlineTimer result;
    result.type = timerType;
    result.t1 = absoluteToNSecs(mach_absolute_time());
    return result;
}

QT_END_NAMESPACE
