本帖最后由 solo777 于 2012-1-10 20:08 编辑
uint8_t tcbEnqueuePriority (ATOM_TCB **tcb_queue_ptr, ATOM_TCB *tcb_ptr)
{
uint8_t status;
ATOM_TCB *prev_ptr, *next_ptr;
/* Parameter check */
if ((tcb_queue_ptr == NULL) || (tcb_ptr == NULL))
{
/* Return error */
status = ATOM_ERR_PARAM;
}
else
{
/* Walk the list and enqueue at the end of the TCBs at this priority */
prev_ptr = next_ptr = *tcb_queue_ptr;
do
{
/* Insert if:
* next_ptr = NULL (we're at the head of an empty queue or at the tail)
* the next TCB in the list is lower priority than the one we're enqueuing.
*/
if ((next_ptr == NULL) || (next_ptr->priority > tcb_ptr->priority))
{
/* Make this TCB the new listhead */
if (next_ptr == *tcb_queue_ptr)//这里也是null呀！
{
*tcb_queue_ptr = tcb_ptr;
tcb_ptr->prev_tcb = NULL; tcb_ptr->next_tcb = next_ptr;
if (next_ptr)
next_ptr->prev_tcb = tcb_ptr;
}
/* Insert between two TCBs or at the tail */
else
{
tcb_ptr->prev_tcb = prev_ptr;
tcb_ptr->next_tcb = next_ptr;
prev_ptr->next_tcb = tcb_ptr;
if (next_ptr)
next_ptr->prev_tcb = tcb_ptr;
}
/* Quit the loop, we've finished inserting */
break;
}
else
{
/* Not inserting here, try the next one */
prev_ptr = next_ptr;
next_ptr = next_ptr->next_tcb;
}
}
while (prev_ptr != NULL);
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