ucos 2.84 中的OSTaskStkChk( )
ucos 2.84 中的OSTaskStkChk( )源码如下：
#if OS_TASK_CREATE_EXT_EN > 0
INT8UOSTaskStkChk (INT8U prio, OS_STK_DATA *p_stk_data)
{
OS_TCB *ptcb;
OS_STK *pchk;
INT32U free;
INT32U size;
#if OS_CRITICAL_METHOD == 3 /* Allocate storage for CPU status register */
OS_CPU_SRcpu_sr = 0;
#endif
#if OS_ARG_CHK_EN > 0
if (prio > OS_LOWEST_PRIO) { /* Make sure task priority is valid */
if (prio != OS_PRIO_SELF) {
return (OS_PRIO_INVALID);
}
}
if (p_stk_data == (OS_STK_DATA *)0) { /* Validate 'p_stk_data' */
return (OS_ERR_PDATA_NULL);
}
#endif
p_stk_data->OSFree = 0; /* Assume failure, set to 0 size */
p_stk_data->OSUsed = 0;
OS_ENTER_CRITICAL();
if (prio == OS_PRIO_SELF) { /* See if check for SELF */
prio = OSTCBCur->OSTCBPrio;
}
ptcb = OSTCBPrioTbl;
if (ptcb == (OS_TCB *)0) { /* Make sure task exist */
OS_EXIT_CRITICAL();
return (OS_TASK_NOT_EXIST);
}
if (ptcb == (OS_TCB *)1) {
OS_EXIT_CRITICAL();
return (OS_TASK_NOT_EXIST);
}
if ((ptcb->OSTCBOpt & OS_TASK_OPT_STK_CHK) == 0) { /* Make sure stack checking option is set */
OS_EXIT_CRITICAL();
return (OS_TASK_OPT_ERR);
}
free = 0;
size = ptcb->OSTCBStkSize;
pchk = ptcb->OSTCBStkBottom;
OS_EXIT_CRITICAL();
#if OS_STK_GROWTH == 1
while (*pchk++ == (OS_STK)0) { /* Compute the number of zero entries on the stk */
free++;
}
#else
while (*pchk-- == (OS_STK)0) {
free++;
}
#endif
p_stk_data->OSFree = free * sizeof(OS_STK); /* Compute number of free bytes on the stack */
p_stk_data->OSUsed = (size - free) * sizeof(OS_STK);/* Compute number of bytes used on the stack */
return (OS_NO_ERR);
}
#endif
请问这段代码：
if (ptcb == (OS_TCB *)0) { /* Make sure task exist */
OS_EXIT_CRITICAL();
return (OS_TASK_NOT_EXIST);
}
if (ptcb == (OS_TCB *)1) {
OS_EXIT_CRITICAL();
return (OS_TASK_NOT_EXIST);
}
怎么理解，我翻看了2.52版源码 并没有判断 ptcb == (OS_TCB *)1，
上述的代码怎么能够保证任务存在？？？
页:
[1]