ucos-iiv2.52毕竟是老版本，现在ucosiii都已经出来很久了，而且马上就可以免费使用了，除了ucgui，因为ucgui是segger的，因此有必要分析一下。源码参考V3.03.00的版本。

解压出来后，是这个结构\Micrium\Software\uCOS-III，

信号量创建函数如下：

/*
************************************************************************************************************************
*                                                  CREATE A SEMAPHORE
*
* Description: This function creates a semaphore.
*
* Arguments  : p_sem         is a pointer to the semaphore to initialize.  Your application is responsible for
*                            allocating storage for the semaphore.
*
*              p_name        is a pointer to the name you would like to give the semaphore.
*
*              cnt           is the initial value for the semaphore.
*                            If used to share resources, you should initialize to the number of resources available.
*                            If used to signal the occurrence of event(s) then you should initialize to 0.
*
*              p_err         is a pointer to a variable that will contain an error code returned by this function.
*
*                                OS_ERR_NONE                    if the call was successful
*                                OS_ERR_CREATE_ISR              if you called this function from an ISR
*                                OS_ERR_ILLEGAL_CREATE_RUN_TIME if you are trying to create the semaphore after you
*                                                                 called OSSafetyCriticalStart().
*                                OS_ERR_NAME                    if 'p_name' is a NULL pointer
*                                OS_ERR_OBJ_CREATED             if the semaphore has already been created
*                                OS_ERR_OBJ_PTR_NULL            if 'p_sem'  is a NULL pointer
*                                OS_ERR_OBJ_TYPE                if 'p_sem' has already been initialized to a different
*                                                               object type
*
* Returns    : none
************************************************************************************************************************
*/

void  OSSemCreate (OS_SEM      *p_sem,
                   CPU_CHAR    *p_name,
                   OS_SEM_CTR   cnt,
                   OS_ERR      *p_err)
{
    CPU_SR_ALLOC();



#ifdef OS_SAFETY_CRITICAL
    if (p_err == (OS_ERR *)0) {
        OS_SAFETY_CRITICAL_EXCEPTION();
        return;
    }
#endif

#ifdef OS_SAFETY_CRITICAL_IEC61508
    if (OSSafetyCriticalStartFlag == DEF_TRUE) {
       *p_err = OS_ERR_ILLEGAL_CREATE_RUN_TIME;
        return;
    }
#endif

#if OS_CFG_CALLED_FROM_ISR_CHK_EN > 0u
    if (OSIntNestingCtr > (OS_NESTING_CTR)0) {              /* Not allowed to be called from an ISR                   */
       *p_err = OS_ERR_CREATE_ISR;
        return;
    }
#endif

#if OS_CFG_ARG_CHK_EN > 0u
    if (p_sem == (OS_SEM *)0) {                             /* Validate 'p_sem'                                       */
       *p_err = OS_ERR_OBJ_PTR_NULL;
        return;
    }
#endif

    OS_CRITICAL_ENTER();
    p_sem->Type    = OS_OBJ_TYPE_SEM;                       /* Mark the data structure as a semaphore                 */
    p_sem->Ctr     = cnt;                                   /* Set semaphore value                                    */
    p_sem->TS      = (CPU_TS)0;
    p_sem->NamePtr = p_name;                                /* Save the name of the semaphore                         */
    OS_PendListInit(&p_sem->PendList);                      /* Initialize the waiting list                            */

#if OS_CFG_DBG_EN > 0u
    OS_SemDbgListAdd(p_sem);
#endif
    OSSemQty++;

    OS_CRITICAL_EXIT_NO_SCHED();
   *p_err = OS_ERR_NONE;
}