{

bool running = true;

//^event-loop

while (running)

{

Event event = getNextEvent();

// 处理事件……

//^omit

use(event);

//^omit

}

//^event-loop

{

public:

static void playSound(SoundId id, int volume);

{

ResourceId resource = loadSound(id);

int channel = findOpenChannel();

if (channel == -1) return;

startSound(resource, channel, volume);

{

public:

void onSelect(int index)

{

Audio::playSound(SOUND_BLOOP, VOL_MAX);

// 其他代码……

}

{

SoundId id;

int volume;

{

public:

static void init()

{

numPending_ = 0;

}

// 其他代码……

//^omit

static void playSound(SoundId id, int volume);

//^omit

private:

static const int MAX_PENDING = 16;

static PlayMessage pending_[MAX_PENDING];

static int numPending_;

{

assert(numPending_ < MAX_PENDING);

pending_[numPending_].id = id;

pending_[numPending_].volume = volume;

numPending_++;

{

public:

static void update()

{

for (int i = 0; i < numPending_; i++)

{

ResourceId resource = loadSound(pending_[i].id);

int channel = findOpenChannel();

if (channel == -1) return;

startSound(resource, channel, pending_[i].volume);

}

numPending_ = 0;

}

// 其他代码……

//^omit

private:

static const int MAX_PENDING = 16;

static PlayMessage pending_[MAX_PENDING];

static int numPending_;

//^omit

{

public:

static void init()

{

head_ = 0;

tail_ = 0;

}

// 方法……

//^omit

static void playSound(SoundId id, int volume);

static void update();

//^omit

private:

//^omit

static const int MAX_PENDING = 16;

static PlayMessage pending_[MAX_PENDING];

//^omit

static int head_;

static int tail_;

// 数组……

{

assert(tail_ < MAX_PENDING);

// Add to the end of the list.

pending_[tail_].id = id;

pending_[tail_].volume = volume;

tail_++;

{

// 如果这里没有待处理的请求

// 那就什么也不做。

if (head_ == tail_) return;

ResourceId resource = loadSound(pending_[head_].id);

int channel = findOpenChannel();

if (channel == -1) return;

startSound(resource, channel, pending_[head_].volume);

head_++;

{

public:

static void init()

{

head_ = 0;

tail_ = 0;

}

static void playSound(SoundId id, int volume);

static void update();

private:

static const int MAX_PENDING = 16;

static PlayMessage pending_[MAX_PENDING];

static int head_;

static int tail_;

{

assert((tail_ + 1) % MAX_PENDING != head_);

// 添加到列表的尾部

pending_[tail_].id = id;

pending_[tail_].volume = volume;

tail_ = (tail_ + 1) % MAX_PENDING;

{

// 如果没有待处理的请求，就啥也不做

if (head_ == tail_) return;

ResourceId resource = loadSound(pending_[head_].id);

int channel = findOpenChannel();

if (channel == -1) return;

startSound(resource, channel, pending_[head_].volume);

head_ = (head_ + 1) % MAX_PENDING;

{

public:

static void init()

{

head_ = 0;

tail_ = 0;

}

static void playSound(SoundId id, int volume);

static void update();

private:

static const int MAX_PENDING = 16;

static PlayMessage pending_[MAX_PENDING];

static int head_;

static int tail_;

{

// 遍历待处理的请求

for (int i = head_; i != tail_;

i = (i + 1) % MAX_PENDING)

{

if (pending_[i].id == id)

{

// 使用较大的音量

pending_[i].volume = max(volume, pending_[i].volume);

// 无需入队

return;

}

}

// 之前的代码……

{

// 如果没有待处理的请求，就什么也不做

if (head_ == tail_) return;

ResourceId resource = loadSound(pending_[head_].id);

int channel = findOpenChannel();

if (channel == -1) return;

startSound(resource, channel, pending_[head_].volume);

head_ = (head_ + 1) % MAX_PENDING;

{

public:

Audio()

: head_(0),

numMessages_(0)

{}

void playSound(SoundId id, int volume)

{

assert(numMessages_ < MAX_MESSAGES);

queue_[head_].id = id;

queue_[head_].volume = volume;

head_ = (head_ + 1) % MAX_MESSAGES;

numMessages_++;

}

void update()

{

}

private:

class SoundMessage

{

public:

SoundId id;

int volume;

};

static const int MAX_MESSAGES = 16;

SoundMessage queue_[MAX_MESSAGES];

int head_;

int numMessages_;