📄 os_task.lst
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200 *********************************************************************************************************
201 * CREATE A TASK (Extended Version)
202 *
203 * Description: This function is used to have uC/OS-II manage the execution of a task. Tasks can either
204 * be created prior to the start of multitasking or by a running task. A task cannot be
205 * created by an ISR. This function is similar to OSTaskCreate() except that it allows
206 * additional information about a task to be specified.
207 *
208 * Arguments : task is a pointer to the task's code
209 *
210 * pdata is a pointer to an optional data area which can be used to pass parameters to
211 * the task when the task first executes. Where the task is concerned it thinks
212 * it was invoked and passed the argument 'pdata' as follows:
213 *
214 * void Task (void *pdata)
215 * {
216 * for (;;) {
217 * Task code;
218 * }
219 * }
220 *
221 * ptos is a pointer to the task's top of stack. If the configuration constant
222 * OS_STK_GROWTH is set to 1, the stack is assumed to grow downward (i.e. from high
223 * memory to low memory). 'ptos' will thus point to the highest (valid) memory
224 * location of the stack. If OS_STK_GROWTH is set to 0, 'ptos' will point to the
225 * lowest memory location of the stack and the stack will grow with increasing
226 * memory locations. 'ptos' MUST point to a valid 'free' data item.
227 *
228 * prio is the task's priority. A unique priority MUST be assigned to each task and the
229 * lower the number, the higher the priority.
230 *
231 * id is the task's ID (0..65535)
232 *
233 * pbos is a pointer to the task's bottom of stack. If the configuration constant
234 * OS_STK_GROWTH is set to 1, the stack is assumed to grow downward (i.e. from high
235 * memory to low memory). 'pbos' will thus point to the LOWEST (valid) memory
236 * location of the stack. If OS_STK_GROWTH is set to 0, 'pbos' will point to the
237 * HIGHEST memory location of the stack and the stack will grow with increasing
238 * memory locations. 'pbos' MUST point to a valid 'free' data item.
239 *
240 * stk_size is the size of the stack in number of elements. If OS_STK is set to INT8U,
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241 * 'stk_size' corresponds to the number of bytes available. If OS_STK is set to
242 * INT16U, 'stk_size' contains the number of 16-bit entries available. Finally, if
243 * OS_STK is set to INT32U, 'stk_size' contains the number of 32-bit entries
244 * available on the stack.
245 *
246 * pext is a pointer to a user supplied memory location which is used as a TCB extension.
247 * For example, this user memory can hold the contents of floating-point registers
248 * during a context switch, the time each task takes to execute, the number of times
249 * the task has been switched-in, etc.
250 *
251 * opt contains additional information (or options) about the behavior of the task. The
252 * LOWER 8-bits are reserved by uC/OS-II while the upper 8 bits can be application
253 * specific. See OS_TASK_OPT_??? in uCOS-II.H.
254 *
255 * Returns : OS_NO_ERR if the function was successful.
256 * OS_PRIO_EXIT if the task priority already exist
257 * (each task MUST have a unique priority).
258 * OS_PRIO_INVALID if the priority you specify is higher that the maximum allowed
259 * (i.e. > OS_LOWEST_PRIO)
260 *********************************************************************************************************
261 */
262 /*$PAGE*/
263 #if OS_TASK_CREATE_EXT_EN > 0
264 INT8U OSTaskCreateExt (void (*task)(void *pd),
265 void *pndata,
266 OS_STK *ptos,
267 INT8U prio,
268 INT16U id,
269 OS_STK *pbos,
270 INT32U stk_size,
271 void *pext,
272 INT16U opt) reentrant //using 0
273 {
274 1 #if OS_CRITICAL_METHOD == 3 /* Allocate storage for CPU status register */
275 1 OS_CPU_SR cpu_sr;
276 1 #endif
277 1 OS_STK *psp;
278 1 INT8U err;
279 1
280 1
281 1 #if OS_ARG_CHK_EN > 0
282 1 if (prio > OS_LOWEST_PRIO) { /* Make sure priority is within allowable range */
283 2 return (OS_PRIO_INVALID);
284 2 }
285 1 #endif
286 1 OS_ENTER_CRITICAL();
287 1 if (OSTCBPrioTbl[prio] == (OS_TCB *)0) { /* Make sure task doesn't already exist at this priority */
288 2 OSTCBPrioTbl[prio] = (OS_TCB *)1; /* Reserve the priority to prevent others from doing ... */
289 2 /* ... the same thing until task is created. */
290 2 OS_EXIT_CRITICAL();
291 2
292 2 OS_TaskStkClr(pbos, stk_size, opt); /* Clear the task stack (if needed) */
293 2
294 2 psp = (OS_STK *)OSTaskStkInit(task, pndata, ptos, opt); /* Initialize the task's stack */
295 2 err = OS_TCBInit(prio, psp, pbos, id, stk_size, pext, opt);
296 2 if (err == OS_NO_ERR) {
297 3 OS_ENTER_CRITICAL();
298 3 OSTaskCtr++; /* Increment the #tasks counter */
299 3 OS_EXIT_CRITICAL();
300 3 if (OSRunning == TRUE) { /* Find HPT if multitasking has started */
301 4 OS_Sched();
302 4 }
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303 3 } else {
304 3 OS_ENTER_CRITICAL();
305 3 OSTCBPrioTbl[prio] = (OS_TCB *)0; /* Make this priority avail. to others */
306 3 OS_EXIT_CRITICAL();
307 3 }
308 2 return (err);
309 2 }
310 1 OS_EXIT_CRITICAL();
311 1 return (OS_PRIO_EXIST);
312 1 }
313 #endif
314 /*$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
351 INT8U OSTaskDel (INT8U prio) reentrant //using 0
352 {
353 1 #if OS_CRITICAL_METHOD == 3 /* Allocate storage for CPU status register */
354 1 OS_CPU_SR cpu_sr;
355 1 #endif
356 1
357 1 #if OS_EVENT_EN > 0
358 1 OS_EVENT *pevent;
359 1 #endif
360 1 #if (OS_VERSION >= 251) && (OS_FLAG_EN > 0) && (OS_MAX_FLAGS > 0)
361 1 OS_FLAG_NODE *pnode;
362 1 #endif
363 1 OS_TCB *ptcb;
364 1 INT8U y;
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365 1
366 1
367 1
368 1 if (OSIntNesting > 0) { /* See if trying to delete from ISR */
369 2 return (OS_TASK_DEL_ISR);
370 2 }
371 1 #if OS_ARG_CHK_EN > 0
372 1 if (prio == OS_IDLE_PRIO) { /* Not allowed to delete idle task */
373 2 return (OS_TASK_DEL_IDLE);
374 2 }
375 1 if (prio >= OS_LOWEST_PRIO && prio != OS_PRIO_SELF) { /* Task priority valid ? */
376 2 return (OS_PRIO_INVALID);
377 2 }
378 1 #endif
379 1 OS_ENTER_CRITICAL();
380 1 if (prio == OS_PRIO_SELF) { /* See if requesting to delete self */
381 2 prio = OSTCBCur->OSTCBPrio; /* Set priority to delete to current */
382 2 }
383 1 ptcb = OSTCBPrioTbl[prio];
384 1 if (ptcb != (OS_TCB *)0) { /* Task to delete must exist */
385 2 y = ptcb->OSTCBY;
386 2 OSRdyTbl[y] &= ~ptcb->OSTCBBitX;
387 2 if (OSRdyTbl[y] == 0x00) { /* Make task not ready */
388 3 OSRdyGrp &= ~ptcb->OSTCBBitY;
389 3 }
390 2 #if OS_EVENT_EN > 0
391 2 pevent = ptcb->OSTCBEventPtr;
392 2 if (pevent != (OS_EVENT *)0) { /* If task is waiting on event */
393 3 pevent->OSEventTbl[y] &= ~ptcb->OSTCBBitX;
394 3 if (pevent->OSEventTbl[y] == 0) { /* ... remove task from ... */
395 4 pevent->OSEventGrp &= ~ptcb->OSTCBBitY; /* ... event ctrl block */
396 4 }
397 3 }
398 2 #endif
399 2 #if (OS_VERSION >= 251) && (OS_FLAG_EN > 0) && (OS_MAX_FLAGS > 0)
400 2 pnode = ptcb->OSTCBFlagNode;
401 2 if (pnode != (OS_FLAG_NODE *)0) { /* If task is waiting on event flag */
402 3 OS_FlagUnlink(pnode); /* Remove from wait list */
403 3 }
404 2 #endif
405 2 ptcb->OSTCBDly = 0; /* Prevent OSTimeTick() from updating */
406 2 ptcb->OSTCBStat = OS_STAT_RDY; /* Prevent task from being resumed */
407 2 if (OSLockNesting < 255u) {
408 3 OSLockNesting++;
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