SDL线程使用

/**
 *  \brief General event structure
 */
typedef union SDL_Event
{
    Uint32 type;                    /**< Event type, shared with all events */
    SDL_CommonEvent common;         /**< Common event data */
    SDL_WindowEvent window;         /**< Window event data */
    SDL_KeyboardEvent key;          /**< Keyboard event data */
    SDL_TextEditingEvent edit;      /**< Text editing event data */
    SDL_TextInputEvent text;        /**< Text input event data */
    SDL_MouseMotionEvent motion;    /**< Mouse motion event data */
    SDL_MouseButtonEvent button;    /**< Mouse button event data */
    SDL_MouseWheelEvent wheel;      /**< Mouse wheel event data */
    SDL_JoyAxisEvent jaxis;         /**< Joystick axis event data */
    SDL_JoyBallEvent jball;         /**< Joystick ball event data */
    SDL_JoyHatEvent jhat;           /**< Joystick hat event data */
    SDL_JoyButtonEvent jbutton;     /**< Joystick button event data */
    SDL_JoyDeviceEvent jdevice;     /**< Joystick device change event data */
    SDL_ControllerAxisEvent caxis;      /**< Game Controller axis event data */
    SDL_ControllerButtonEvent cbutton;  /**< Game Controller button event data */
    SDL_ControllerDeviceEvent cdevice;  /**< Game Controller device event data */
    SDL_AudioDeviceEvent adevice;   /**< Audio device event data */
    SDL_QuitEvent quit;             /**< Quit request event data */
    SDL_UserEvent user;             /**< Custom event data */
    SDL_SysWMEvent syswm;           /**< System dependent window event data */
    SDL_TouchFingerEvent tfinger;   /**< Touch finger event data */
    SDL_MultiGestureEvent mgesture; /**< Gesture event data */
    SDL_DollarGestureEvent dgesture; /**< Gesture event data */
    SDL_DropEvent drop;             /**< Drag and drop event data */
    /* This is necessary for ABI compatibility between Visual C++ and GCC
       Visual C++ will respect the push pack pragma and use 52 bytes for
       this structure, and GCC will use the alignment of the largest datatype
       within the union, which is 8 bytes.
       So... we‘ll add padding to force the size to be 56 bytes for both.
    */
    Uint8 padding[56];
} SDL_Event;

/* The SDL mutex structure, defined in SDL_sysmutex.c */
struct SDL_mutex;
typedef struct SDL_mutex SDL_mutex;

/**
 *  Create a mutex, initialized unlocked.
 */
extern DECLSPEC SDL_mutex *SDLCALL SDL_CreateMutex(void);

/**
 *  Lock the mutex.
 *
 *  \return 0, or -1 on error.
 */
#define SDL_mutexP(m)   SDL_LockMutex(m)
extern DECLSPEC int SDLCALL SDL_LockMutex(SDL_mutex * mutex);
/**
 *  Try to lock the mutex
 *
 *  \return 0, SDL_MUTEX_TIMEDOUT, or -1 on error
 */
extern DECLSPEC int SDLCALL SDL_TryLockMutex(SDL_mutex * mutex);

/**
 *  Unlock the mutex.
 *
 *  \return 0, or -1 on error.
 *
 *  \warning It is an error to unlock a mutex that has not been locked by
 *           the current thread, and doing so results in undefined behavior.
 */
#define SDL_mutexV(m)   SDL_UnlockMutex(m)
extern DECLSPEC int SDLCALL SDL_UnlockMutex(SDL_mutex * mutex);

/**
 *  Destroy a mutex.
 */
extern DECLSPEC void SDLCALL SDL_DestroyMutex(SDL_mutex * mutex);

/* The SDL condition variable structure, defined in SDL_syscond.c */
struct SDL_cond;
typedef struct SDL_cond SDL_cond;

/**
 *  Create a condition variable.
 *
 *  Typical use of condition variables:
 *
 *  Thread A:
 *    SDL_LockMutex(lock);
 *    while ( ! condition ) {
 *        SDL_CondWait(cond, lock);
 *    }
 *    SDL_UnlockMutex(lock);
 *
 *  Thread B:
 *    SDL_LockMutex(lock);
 *    ...
 *    condition = true;
 *    ...
 *    SDL_CondSignal(cond);
 *    SDL_UnlockMutex(lock);
 *
 *  There is some discussion whether to signal the condition variable
 *  with the mutex locked or not.  There is some potential performance
 *  benefit to unlocking first on some platforms, but there are some
 *  potential race conditions depending on how your code is structured.
 *
 *  In general it‘s safer to signal the condition variable while the
 *  mutex is locked.
 */
extern DECLSPEC SDL_cond *SDLCALL SDL_CreateCond(void);

/**
 *  Destroy a condition variable.
 */
extern DECLSPEC void SDLCALL SDL_DestroyCond(SDL_cond * cond);

/**
 *  Restart one of the threads that are waiting on the condition variable.
 *
 *  \return 0 or -1 on error.
 */
extern DECLSPEC int SDLCALL SDL_CondSignal(SDL_cond * cond);

/**
 *  Restart all threads that are waiting on the condition variable.
 *
 *  \return 0 or -1 on error.
 */
extern DECLSPEC int SDLCALL SDL_CondBroadcast(SDL_cond * cond);

/**
 *  Wait on the condition variable, unlocking the provided mutex.
 *
 *  \warning The mutex must be locked before entering this function!
 *
 *  The mutex is re-locked once the condition variable is signaled.
 *
 *  \return 0 when it is signaled, or -1 on error.
 */
extern DECLSPEC int SDLCALL SDL_CondWait(SDL_cond * cond, SDL_mutex * mutex);