lwIP（Light Weight IP）协议

• 信号量

　　信号量结构体：struct sys_semt

　　　　struct _sys_sem {
　　　　void *sem;
　　　　};

 err_t sys_sem_new(sys_sem_t *sem, u8_t count)                 新建信号量

err_t sys_sem_new(sys_sem_t *sem, u8_t count)                         //err_t为signed char类型,sys_sem_t为struct sys_semt类型
{
　　HANDLE new_sem = NULL;

LWIP_ASSERT("sem != NULL", sem != NULL);

new_sem = CreateSemaphore(0, count, 100000, 0);            //创建一个信号量，创建出错返回0

LWIP_ASSERT("Error creating semaphore", new_sem != NULL);

if(new_sem != NULL)

{

if (SYS_INITIALIZED()) {

SYS_ARCH_LOCKED(SYS_STATS_INC_USED(sem));

} else {

SYS_STATS_INC_USED(sem);

}
#if LWIP_STATS && SYS_STATS

LWIP_ASSERT("sys_sem_new() counter overflow", lwip_stats.sys.sem.used != 0);

#endif /* LWIP_STATS && SYS_STATS*/

sem->sem = new_sem;

return ERR_OK;

}

/* failed to allocate memory... */

if (SYS_INITIALIZED()) {

SYS_ARCH_LOCKED(SYS_STATS_INC(sem.err));

} else {

   SYS_STATS_INC(sem.err);

}
sem->sem = NULL;
return ERR_MEM;

}

　　　　　　

        void sys_sem_signal(sys_sem_t *sem)                                  发送信号量

        u32_t sys_arch_sem_wait(sys_sem_t *sem, u32_t timeout) 等待信号量

        void sys_sem_free(sys_sem_t *sem)                                        删除信号量

void sys_sem_free(sys_sem_t *sem)

{

/* parameter check */

LWIP_ASSERT("sem != NULL", sem != NULL);

LWIP_ASSERT("sem->sem != NULL", sem->sem != NULL);

LWIP_ASSERT("sem->sem != INVALID_HANDLE_VALUE", sem->sem != INVALID_HANDLE_VALUE);

CloseHandle(sem->sem);

SYS_ARCH_LOCKED(SYS_STATS_DEC(sem.used));

#if LWIP_STATS && SYS_STATS

LWIP_ASSERT("sys_sem_free() closed more than created", lwip_stats.sys.sem.used != (u16_t)-1);

#endif /* LWIP_STATS && SYS_STATS */

sem->sem = NULL;

}

        int sys_sem_valid(sys_sem_t *sem)                                        查询是否可用

        void sys_sem_set_invalid(sys_sem_t *sem)                            设置为失效

　　　

　　  void sys_timeout(u32_t msecs, sys_timeout_handler h, void *arg)//设置一个超时事件

  　　void sys_untimeout(sys_timeout_handler h, void *arg)//删除一个超时事件

• 互斥锁

　　

　　err_t sys_mutex_new(sys_mutex_t *mutex)                  新建锁

        void sys_mutex_lock(sys_mutex_t *mutex)                  获取锁

        void sys_mutex_unlock(sys_mutex_t *mutex)             释放锁

        void sys_mutex_free(sys_mutex_t *mutex)                   删除锁

        int sys_mutex_valid(sys_mutex_t *mutex)                    查询锁是否可用

        void sys_mutex_set_invalid(sys_mutex_t *mutex)        设置锁为失效

• 创建线程

　　sys_thread_t sys_thread_new(const char *name, lwip_thread_fn thread, void *arg, int stacksize, int prio)