src/third_party/WebKit/Source/WTF/wtf/MediaTime.cpp

/*
 * Copyright (C) 2012 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "config.h"
#include "MediaTime.h"

#include <algorithm>
#include <wtf/CheckedArithmetic.h>
#include <wtf/MathExtras.h>

using namespace std;

namespace WTF {

static int32_t greatestCommonDivisor(int32_t a, int32_t b)
{
    // Euclid's Algorithm
    int32_t temp = 0;
    while (b) {
        temp = b;
        b = a % b;
        a = temp;
    }
    return a;
}

static int32_t leastCommonMultiple(int32_t a, int32_t b, int32_t &result)
{
    return safeMultiply(a, b / greatestCommonDivisor(a, b), result);
}

const int32_t MediaTime::MaximumTimeScale = 0x7fffffffL;

MediaTime::MediaTime()
    : m_timeValue(0)
    , m_timeScale(DefaultTimeScale)
    , m_timeFlags(Valid)
{
}

MediaTime::MediaTime(int64_t value, int32_t scale, uint32_t flags)
    : m_timeValue(value)
    , m_timeScale(scale)
    , m_timeFlags(flags)
{
}

MediaTime::~MediaTime()
{
}

MediaTime::MediaTime(const MediaTime& rhs)
{
    *this = rhs;
}

MediaTime MediaTime::createWithFloat(float floatTime, int32_t timeScale)
{
    if (floatTime != floatTime)
        return invalidTime();
    if (isinf(floatTime))
        return signbit(floatTime) ? negativeInfiniteTime() : positiveInfiniteTime();
    if (floatTime > numeric_limits<int64_t>::max())
        return positiveInfiniteTime();
    if (floatTime < numeric_limits<int64_t>::min())
        return negativeInfiniteTime();

    while (floatTime * timeScale > numeric_limits<int64_t>::max())
        timeScale /= 2;
    return MediaTime(static_cast<int64_t>(floatTime * timeScale), timeScale, Valid);
}

MediaTime MediaTime::createWithDouble(double doubleTime, int32_t timeScale)
{
    if (doubleTime != doubleTime)
        return invalidTime();
    if (isinf(doubleTime))
        return signbit(doubleTime) ? negativeInfiniteTime() : positiveInfiniteTime();
    if (doubleTime > numeric_limits<int64_t>::max())
        return positiveInfiniteTime();
    if (doubleTime < numeric_limits<int64_t>::min())
        return negativeInfiniteTime();

    while (doubleTime * timeScale > numeric_limits<int64_t>::max())
        timeScale /= 2;
    return MediaTime(static_cast<int64_t>(doubleTime * timeScale), timeScale, Valid);
}

float MediaTime::toFloat() const
{
    if (isInvalid() || isIndefinite())
        return std::numeric_limits<float>::quiet_NaN();
    if (isPositiveInfinite())
        return std::numeric_limits<float>::infinity();
    if (isNegativeInfinite())
        return -std::numeric_limits<float>::infinity();
    return static_cast<float>(m_timeValue) / m_timeScale;
}

double MediaTime::toDouble() const
{
    if (isInvalid() || isIndefinite())
        return std::numeric_limits<double>::quiet_NaN();
    if (isPositiveInfinite())
        return std::numeric_limits<double>::infinity();
    if (isNegativeInfinite())
        return -std::numeric_limits<double>::infinity();
    return static_cast<double>(m_timeValue) / m_timeScale;
}

MediaTime& MediaTime::operator=(const MediaTime& rhs)
{
    m_timeValue = rhs.m_timeValue;
    m_timeScale = rhs.m_timeScale;
    m_timeFlags = rhs.m_timeFlags;
    return *this;
}

MediaTime MediaTime::operator+(const MediaTime& rhs) const
{
    if (rhs.isInvalid() || isInvalid())
        return invalidTime();

    if (rhs.isIndefinite() || isIndefinite())
        return indefiniteTime();

    if (isPositiveInfinite()) {
        if (rhs.isNegativeInfinite())
            return invalidTime();
        return positiveInfiniteTime();
    }

    if (isNegativeInfinite()) {
        if (rhs.isPositiveInfinite())
            return invalidTime();
        return negativeInfiniteTime();
    }

    int32_t commonTimeScale;
    if (!leastCommonMultiple(this->m_timeScale, rhs.m_timeScale, commonTimeScale) || commonTimeScale > MaximumTimeScale)
        commonTimeScale = MaximumTimeScale;
    MediaTime a = *this;
    MediaTime b = rhs;
    a.setTimeScale(commonTimeScale);
    b.setTimeScale(commonTimeScale);
    while (!safeAdd(a.m_timeValue, b.m_timeValue, a.m_timeValue)) {
        if (commonTimeScale == 1)
            return a.m_timeValue > 0 ? positiveInfiniteTime() : negativeInfiniteTime();
        commonTimeScale /= 2;
        a.setTimeScale(commonTimeScale);
        b.setTimeScale(commonTimeScale);
    }
    return a;
}

MediaTime MediaTime::operator-(const MediaTime& rhs) const
{
    if (rhs.isInvalid() || isInvalid())
        return invalidTime();

    if (rhs.isIndefinite() || isIndefinite())
        return indefiniteTime();

    if (isPositiveInfinite()) {
        if (rhs.isPositiveInfinite())
            return invalidTime();
        return positiveInfiniteTime();
    }

    if (isNegativeInfinite()) {
        if (rhs.isNegativeInfinite())
            return invalidTime();
        return negativeInfiniteTime();
    }

    int32_t commonTimeScale;
    if (!leastCommonMultiple(this->m_timeScale, rhs.m_timeScale, commonTimeScale) || commonTimeScale > MaximumTimeScale)
        commonTimeScale = MaximumTimeScale;
    MediaTime a = *this;
    MediaTime b = rhs;
    a.setTimeScale(commonTimeScale);
    b.setTimeScale(commonTimeScale);
    while (!safeSub(a.m_timeValue, b.m_timeValue, a.m_timeValue)) {
        if (commonTimeScale == 1)
            return a.m_timeValue > 0 ? positiveInfiniteTime() : negativeInfiniteTime();
        commonTimeScale /= 2;
        a.setTimeScale(commonTimeScale);
        b.setTimeScale(commonTimeScale);
    }
    return a;
}

bool MediaTime::operator<(const MediaTime& rhs) const
{
    return compare(rhs) == LessThan;
}

bool MediaTime::operator>(const MediaTime& rhs) const
{
    return compare(rhs) == GreaterThan;
}

bool MediaTime::operator==(const MediaTime& rhs) const
{
    return compare(rhs) == EqualTo;
}

bool MediaTime::operator>=(const MediaTime& rhs) const
{
    return compare(rhs) >= EqualTo;
}

bool MediaTime::operator<=(const MediaTime& rhs) const
{
    return compare(rhs) <= EqualTo;
}

MediaTime::ComparisonFlags MediaTime::compare(const MediaTime& rhs) const
{
    if ((isPositiveInfinite() && rhs.isPositiveInfinite())
        || (isNegativeInfinite() && rhs.isNegativeInfinite())
        || (isInvalid() && rhs.isInvalid())
        || (isIndefinite() && rhs.isIndefinite()))
        return EqualTo;

    if (isInvalid())
        return GreaterThan;

    if (rhs.isInvalid())
        return LessThan;

    if (rhs.isNegativeInfinite() || isPositiveInfinite())
        return GreaterThan;

    if (rhs.isPositiveInfinite() || isNegativeInfinite())
        return LessThan;

    if (isIndefinite())
        return GreaterThan;

    if (rhs.isIndefinite())
        return LessThan;

    int64_t rhsWhole = rhs.m_timeValue / rhs.m_timeScale;
    int64_t lhsWhole = m_timeValue / m_timeScale;
    if (lhsWhole > rhsWhole)
        return GreaterThan;
    if (lhsWhole < rhsWhole)
        return LessThan;

    int64_t rhsRemain = rhs.m_timeValue % rhs.m_timeScale;
    int64_t lhsRemain = m_timeValue % m_timeScale;
    int64_t lhsFactor = lhsRemain * rhs.m_timeScale;
    int64_t rhsFactor = rhsRemain * m_timeScale;

    if (lhsFactor == rhsFactor)
        return EqualTo;
    return lhsFactor > rhsFactor ? GreaterThan : LessThan;
}

const MediaTime& MediaTime::zeroTime()
{
    static const MediaTime* time = new MediaTime(0, 1, Valid);
    return *time;
}

const MediaTime& MediaTime::invalidTime()
{
    static const MediaTime* time = new MediaTime(-1, 1, 0);
    return *time;
}

const MediaTime& MediaTime::positiveInfiniteTime()
{
    static const MediaTime* time = new MediaTime(0, 1, PositiveInfinite | Valid);
    return *time;
}

const MediaTime& MediaTime::negativeInfiniteTime()
{
    static const MediaTime* time = new MediaTime(-1, 1, NegativeInfinite | Valid);
    return *time;
}

const MediaTime& MediaTime::indefiniteTime()
{
    static const MediaTime* time = new MediaTime(0, 1, Indefinite | Valid);
    return *time;
}

void MediaTime::setTimeScale(int32_t timeScale)
{
    if (timeScale == m_timeScale)
        return;
    timeScale = std::min(MaximumTimeScale, timeScale);
    int64_t wholePart = m_timeValue / m_timeScale;

    // If setting the time scale will cause an overflow, divide the
    // timescale by two until the number will fit, and round the
    // result.
    int64_t newWholePart;
    while (!safeMultiply(wholePart, timeScale, newWholePart))
        timeScale /= 2;

    int64_t remainder = m_timeValue % m_timeScale;
    m_timeValue = newWholePart + (remainder * timeScale) / m_timeScale;
    m_timeScale = timeScale;
}

static int32_t signum(int64_t val)
{
    return (0 < val) - (val < 0);
}

MediaTime abs(const MediaTime& rhs)
{
    if (rhs.isInvalid())
        return MediaTime::invalidTime();
    if (rhs.isNegativeInfinite() || rhs.isPositiveInfinite())
        return MediaTime::positiveInfiniteTime();
    MediaTime val = rhs;
    val.m_timeValue *= signum(rhs.m_timeScale) * signum(rhs.m_timeValue);
    return val;
}

}