📄 os_task.lst
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182 3 } else {
183 3 OS_ENTER_CRITICAL();
184 3 OSTCBPrioTbl[prio] = (OS_TCB *)0;/* Make this priority available to others */
185 3 OS_EXIT_CRITICAL();
186 3 }
187 2 return (err);
188 2 }
189 1 OS_EXIT_CRITICAL();
190 1 return (OS_PRIO_EXIST);
191 1 }
192 #endif
193 /*$PAGE*/
194 /*
195 *********************************************************************************************************
196 * CREATE A TASK (Extended Version)
197 *
198 * Description: This function is used to have uC/OS-II manage the execution of a task. Tasks can either
199 * be created prior to the start of multitasking or by a running task. A task cannot be
200 * created by an ISR. This function is similar to OSTaskCreate() except that it allows
201 * additional information about a task to be specified.
202 *
203 * Arguments : task is a pointer to the task's code
204 *
205 * pdata is a pointer to an optional data area which can be used to pass parameters to
206 * the task when the task first executes. Where the task is concerned it thinks
207 * it was invoked and passed the argument 'pdata' as follows:
208 *
209 * void Task (void *pdata)
210 * {
211 * for (;;) {
212 * Task code;
213 * }
214 * }
215 *
216 * ptos is a pointer to the task's top of stack. If the configuration constant
217 * OS_STK_GROWTH is set to 1, the stack is assumed to grow downward (i.e. from high
218 * memory to low memory). 'pstk' will thus point to the highest (valid) memory
219 * location of the stack. If OS_STK_GROWTH is set to 0, 'pstk' will point to the
220 * lowest memory location of the stack and the stack will grow with increasing
221 * memory locations. 'pstk' MUST point to a valid 'free' data item.
222 *
223 * prio is the task's priority. A unique priority MUST be assigned to each task and the
224 * lower the number, the higher the priority.
225 *
226 * id is the task's ID (0..65535)
227 *
228 * pbos is a pointer to the task's bottom of stack. If the configuration constant
229 * OS_STK_GROWTH is set to 1, the stack is assumed to grow downward (i.e. from high
230 * memory to low memory). 'pbos' will thus point to the LOWEST (valid) memory
231 * location of the stack. If OS_STK_GROWTH is set to 0, 'pbos' will point to the
232 * HIGHEST memory location of the stack and the stack will grow with increasing
233 * memory locations. 'pbos' MUST point to a valid 'free' data item.
234 *
235 * stk_size is the size of the stack in number of elements. If OS_STK is set to INT8U,
236 * 'stk_size' corresponds to the number of bytes available. If OS_STK is set to
237 * INT16U, 'stk_size' contains the number of 16-bit entries available. Finally, if
238 * OS_STK is set to INT32U, 'stk_size' contains the number of 32-bit entries
239 * available on the stack.
240 *
241 * pext is a pointer to a user supplied memory location which is used as a TCB extension.
C51 COMPILER V7.50 OS_TASK 08/08/2005 11:36:54 PAGE 5
242 * For example, this user memory can hold the contents of floating-point registers
243 * during a context switch, the time each task takes to execute, the number of times
244 * the task has been switched-in, etc.
245 *
246 * opt contains additional information (or options) about the behavior of the task. The
247 * LOWER 8-bits are reserved by uC/OS-II while the upper 8 bits can be application
248 * specific. See OS_TASK_OPT_??? in uCOS-II.H.
249 *
250 * Returns : OS_NO_ERR if the function was successful.
251 * OS_PRIO_EXIT if the task priority already exist
252 * (each task MUST have a unique priority).
253 * OS_PRIO_INVALID if the priority you specify is higher that the maximum allowed
254 * (i.e. > OS_LOWEST_PRIO)
255 *********************************************************************************************************
256 */
257 /*$PAGE*/
258 #if OS_TASK_CREATE_EXT_EN > 0
INT8U OSTaskCreateExt (void (*task)(void *pd),
void *ppdata,
OS_STK *ptos,
INT8U prio,
INT16U id,
OS_STK *pbos,
INT32U stk_size,
void *pext,
INT16U opt)
{
OS_STK *psp;
INT8U err;
#if OS_ARG_CHK_EN > 0
if (prio > OS_LOWEST_PRIO) { /* Make sure priority is within allowable range */
return (OS_PRIO_INVALID);
}
#endif
OS_ENTER_CRITICAL();
if (OSTCBPrioTbl[prio] == (OS_TCB *)0) { /* Make sure task doesn't already exist at this priority */
OSTCBPrioTbl[prio] = (OS_TCB *)1; /* Reserve the priority to prevent others from doing ... */
/* ... the same thing until task is created. */
OS_EXIT_CRITICAL();
if (((opt & OS_TASK_OPT_STK_CHK) != 0x0000) || /* See if stack checking has been enabled */
((opt & OS_TASK_OPT_STK_CLR) != 0x0000)) { /* See if stack needs to be cleared */
#if OS_STK_GROWTH == 1
(void)memset(pbos, 0, stk_size * sizeof(OS_STK));
#else
(void)memset(ptos, 0, stk_size * sizeof(OS_STK));
#endif
}
psp = (OS_STK *)OSTaskStkInit(task, ppdata, ptos, opt); /* Initialize the task's stack */
err = OS_TCBInit(prio, psp, pbos, id, stk_size, pext, opt);
if (err == OS_NO_ERR) {
OS_ENTER_CRITICAL();
OSTaskCtr++; /* Increment the #tasks counter */
OS_EXIT_CRITICAL();
if (OSRunning == TRUE) { /* Find HPT if multitasking has started */
OS_Sched();
}
} else {
C51 COMPILER V7.50 OS_TASK 08/08/2005 11:36:54 PAGE 6
OS_ENTER_CRITICAL();
OSTCBPrioTbl[prio] = (OS_TCB *)0; /* Make this priority avail. to others */
OS_EXIT_CRITICAL();
}
return (err);
}
OS_EXIT_CRITICAL();
return (OS_PRIO_EXIST);
}
#endif
314 /*$PAGE*/
315 /*
316 *********************************************************************************************************
317 * DELETE A TASK
318 *
319 * Description: This function allows you to delete a task. The calling task can delete itself by
320 * its own priority number. The deleted task is returned to the dormant state and can be
321 * re-activated by creating the deleted task again.
322 *
323 * Arguments : prio is the priority of the task to delete. Note that you can explicitely delete
324 * the current task without knowing its priority level by setting 'prio' to
325 * OS_PRIO_SELF.
326 *
327 * Returns : OS_NO_ERR if the call is successful
328 * OS_TASK_DEL_IDLE if you attempted to delete uC/OS-II's idle task
329 * OS_PRIO_INVALID if the priority you specify is higher that the maximum allowed
330 * (i.e. >= OS_LOWEST_PRIO) or, you have not specified OS_PRIO_SELF.
331 * OS_TASK_DEL_ERR if the task you want to delete does not exist
332 * OS_TASK_DEL_ISR if you tried to delete a task from an ISR
333 *
334 * Notes : 1) To reduce interrupt latency, OSTaskDel() 'disables' the task:
335 * a) by making it not ready
336 * b) by removing it from any wait lists
337 * c) by preventing OSTimeTick() from making the task ready to run.
338 * The task can then be 'unlinked' from the miscellaneous structures in uC/OS-II.
339 * 2) The function OS_Dummy() is called after OS_EXIT_CRITICAL() because, on most processors,
340 * the next instruction following the enable interrupt instruction is ignored.
341 * 3) An ISR cannot delete a task.
342 * 4) The lock nesting counter is incremented because, for a brief instant, if the current
343 * task is being deleted, the current task would not be able to be rescheduled because it
344 * is removed from the ready list. Incrementing the nesting counter prevents another task
345 * from being schedule. This means that an ISR would return to the current task which is
346 * being deleted. The rest of the deletion would thus be able to be completed.
347 *********************************************************************************************************
348 */
349 /*$PAGE*/
350 #if OS_TASK_DEL_EN > 0
INT8U OSTaskDel (INT8U prio)
{
#if OS_EVENT_EN > 0
OS_EVENT *pevent;
#endif
#if (OS_VERSION >= 251) && (OS_FLAG_EN > 0) && (OS_MAX_FLAGS > 0)
OS_FLAG_NODE *pnode;
#endif
OS_TCB *ptcb;
C51 COMPILER V7.50 OS_TASK 08/08/2005 11:36:54 PAGE 7
if (OSIntNesting > 0) { /* See if trying to delete from ISR */
return (OS_TASK_DEL_ISR);
}
#if OS_ARG_CHK_EN > 0
if (prio == OS_IDLE_PRIO) { /* Not allowed to delete idle task */
return (OS_TASK_DEL_IDLE);
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