1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
|
/*
Nil RTOS - Copyright (C) 2012 Giovanni Di Sirio.
This file is part of Nil RTOS.
Nil RTOS is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
Nil RTOS is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* @file nil.c
* @brief Nil RTOS main source file.
*
* @defgroup nil
* @details Nil RTOS services.
* @{
*/
#include "nil.h"
/*===========================================================================*/
/* Module local definitions. */
/*===========================================================================*/
/*===========================================================================*/
/* Module exported variables. */
/*===========================================================================*/
/**
* @brief System data structures.
*/
nil_system_t nil;
/*===========================================================================*/
/* Module local variables. */
/*===========================================================================*/
/*===========================================================================*/
/* Module local functions. */
/*===========================================================================*/
/*===========================================================================*/
/* Module interrupt handlers. */
/*===========================================================================*/
/*===========================================================================*/
/* Module exported functions. */
/*===========================================================================*/
/**
* @brief Initializes the kernel.
* @details Initializes the kernel structures, the current instructions flow
* becomes the idle thread upon return. The idle thread must not
* invoke any kernel primitive able to change state to not runnable.
* @note This function assumes that the @p nil global variable has been
* zeroed by the runtime environment. If this is not the case then
* make sure to clear it before calling this function.
*
* @special
*/
void chSysInit(void) {
thread_t *tp;
const thread_config_t *tcp;
/* Port layer initialization.*/
port_init();
/* Iterates through the list of defined threads.*/
tp = &nil.threads[0];
tcp = nil_thd_configs;
while (tp < &nil.threads[NIL_CFG_NUM_THREADS]) {
#if NIL_CFG_ENABLE_STACK_CHECK
tp->stklim = (stkalign_t *)tcp->wbase;
#endif
/* Port dependent thread initialization.*/
PORT_SETUP_CONTEXT(tp, tcp->wend, tcp->funcp, tcp->arg);
/* Initialization hook.*/
#if defined(NIL_CFG_THREAD_EXT_INIT_HOOK)
NIL_CFG_THREAD_EXT_INIT_HOOK(tp);
#endif
tp++, tcp++;
}
#if NIL_CFG_ENABLE_STACK_CHECK
/* The idle thread is a special case because its stack is set up by the
runtime environment.*/
tp->stklim = THD_IDLE_BASE;
#endif
/* Runs the highest priority thread, the current one becomes the null
thread.*/
nil.current = nil.next = nil.threads;
port_switch(nil.current, tp);
/* Interrupts enabled for the idle thread.*/
chSysEnable();
}
/**
* @brief Halts the system.
* @details This function is invoked by the operating system when an
* unrecoverable error is detected, for example because a programming
* error in the application code that triggers an assertion while
* in debug mode.
* @note Can be invoked from any system state.
*
* @special
*/
void chSysHalt(const char *reason) {
port_disable();
#if NIL_DBG_ENABLED
nil.dbg_panic_msg = reason;
#else
(void)reason;
#endif
#if defined(NIL_CFG_SYSTEM_HALT_HOOK) || defined(__DOXYGEN__)
NIL_CFG_SYSTEM_HALT_HOOK(reason);
#endif
/* Harmless infinite loop.*/
while (true)
;
}
/**
* @brief Time management handler.
* @note This handler has to be invoked by a periodic ISR in order to
* reschedule the waiting threads.
*
* @iclass
*/
void chSysTimerHandlerI(void) {
#if NIL_CFG_ST_TIMEDELTA == 0
thread_t *tp = &nil.threads[0];
nil.systime++;
do {
/* Is the thread in a wait state with timeout?.*/
if (tp->timeout > 0) {
chDbgAssert(!NIL_THD_IS_READY(tp), "is ready");
/* Did the timer reach zero?*/
if (--tp->timeout == 0) {
/* Timeout on semaphores requires a special handling because the
semaphore counter must be incremented.*/
if (NIL_THD_IS_WTSEM(tp))
tp->u1.semp->cnt++;
else if (NIL_THD_IS_SUSP(tp))
*tp->u1.trp = NULL;
chSchReadyI(tp, MSG_TIMEOUT);
}
}
/* Lock released in order to give a preemption chance on those
architectures supporting IRQ preemption.*/
chSysUnlockFromISR();
tp++;
chSysLockFromISR();
} while (tp < &nil.threads[NIL_CFG_NUM_THREADS]);
#else
thread_t *tp = &nil.threads[0];
systime_t next = 0;
chDbgAssert(nil.nexttime == port_timer_get_alarm(), "time mismatch");
do {
/* Is the thread in a wait state with timeout?.*/
if (tp->timeout > 0) {
chDbgAssert(!NIL_THD_IS_READY(tp), "is ready");
chDbgAssert(tp->timeout >= nil.nexttime - nil.lasttime, "skipped one");
tp->timeout -= nil.nexttime - nil.lasttime;
if (tp->timeout == 0) {
/* Timeout on semaphores requires a special handling because the
semaphore counter must be incremented.*/
if (NIL_THD_IS_WTSEM(tp))
tp->u1.semp->cnt++;
else if (NIL_THD_IS_SUSP(tp))
*tp->u1.trp = NULL;
chSchReadyI(tp, MSG_TIMEOUT);
}
else {
if (tp->timeout <= next - 1)
next = tp->timeout;
}
}
/* Lock released in order to give a preemption chance on those
architectures supporting IRQ preemption.*/
chSysUnlockFromISR();
tp++;
chSysLockFromISR();
} while (tp < &nil.threads[NIL_CFG_NUM_THREADS]);
nil.lasttime = nil.nexttime;
if (next > 0) {
nil.nexttime += next;
port_timer_set_alarm(nil.nexttime);
}
else {
/* No tick event needed.*/
port_timer_stop_alarm();
}
#endif
}
/**
* @brief Returns the execution status and enters a critical zone.
* @details This functions enters into a critical zone and can be called
* from any context. Because its flexibility it is less efficient
* than @p chSysLock() which is preferable when the calling context
* is known.
* @post The system is in a critical zone.
*
* @return The previous system status, the encoding of this
* status word is architecture-dependent and opaque.
*
* @xclass
*/
syssts_t chSysGetStatusAndLockX(void) {
syssts_t sts = port_get_irq_status();
if (port_irq_enabled(sts)) {
if (port_is_isr_context())
chSysLockFromISR();
else
chSysLock();
}
return sts;
}
/**
* @brief Restores the specified execution status and leaves a critical zone.
* @note A call to @p chSchRescheduleS() is automatically performed
* if exiting the critical zone and if not in ISR context.
*
* @param[in] sts the system status to be restored.
*
* @xclass
*/
void chSysRestoreStatusX(syssts_t sts) {
if (port_irq_enabled(sts)) {
if (port_is_isr_context())
chSysUnlockFromISR();
else {
chSchRescheduleS();
chSysUnlock();
}
}
}
/**
* @brief Makes the specified thread ready for execution.
*
* @param[in] tp pointer to the @p thread_t object
* @param[in] msg the wakeup message
*
* @return The same reference passed as parameter.
*/
thread_t *chSchReadyI(thread_t *tp, msg_t msg) {
chDbgAssert((tp >= nil.threads) &&
(tp < &nil.threads[NIL_CFG_NUM_THREADS]),
"pointer out of range");
chDbgAssert(!NIL_THD_IS_READY(tp), "already ready");
chDbgAssert(nil.next <= nil.current, "priority ordering");
tp->u1.msg = msg;
tp->state = NIL_STATE_READY;
tp->timeout = 0;
if (tp < nil.next)
nil.next = tp;
return tp;
}
/**
* @brief Reschedules if needed.
*
* @sclass
*/
void chSchRescheduleS(void) {
if (chSchIsRescRequiredI()) {
thread_t *otp = nil.current;
nil.current = nil.next;
#if defined(NIL_CFG_IDLE_LEAVE_HOOK)
if (otp == &nil.threads[NIL_CFG_NUM_THREADS]) {
NIL_CFG_IDLE_LEAVE_HOOK();
}
#endif
port_switch(nil.next, otp);
}
}
/**
* @brief Puts the current thread to sleep into the specified state with
* timeout specification.
* @details The thread goes into a sleeping state, if it is not awakened
* explicitly within the specified system time then it is forcibly
* awakened with a @p NIL_MSG_TMO low level message.
*
* @param[in] newstate the new thread state or a semaphore pointer
* @param[in] timeout the number of ticks before the operation timeouts.
* the following special values are allowed:
* - @a TIME_INFINITE no timeout.
* .
* @return The wakeup message.
* @retval NIL_MSG_TMO if a timeout occurred.
*
* @sclass
*/
msg_t chSchGoSleepTimeoutS(tstate_t newstate, systime_t timeout) {
thread_t *ntp, *otp = nil.current;
chDbgAssert(otp != &nil.threads[NIL_CFG_NUM_THREADS],
"idle cannot sleep");
/* Storing the wait object for the current thread.*/
otp->state = newstate;
#if NIL_CFG_ST_TIMEDELTA > 0
if (timeout != TIME_INFINITE) {
systime_t abstime;
/* TIMEDELTA makes sure to have enough time to reprogram the timer
before the free-running timer counter reaches the selected timeout.*/
if (timeout < NIL_CFG_ST_TIMEDELTA)
timeout = NIL_CFG_ST_TIMEDELTA;
/* Absolute time of the timeout event.*/
abstime = chVTGetSystemTimeX() + timeout;
if (nil.lasttime == nil.nexttime) {
/* Special case, first thread asking for a timeout.*/
port_timer_start_alarm(abstime);
nil.nexttime = abstime;
}
else {
/* Special case, there are already other threads with a timeout
activated, evaluating the order.*/
if (chVTIsTimeWithinX(abstime, nil.lasttime, nil.nexttime)) {
port_timer_set_alarm(abstime);
nil.nexttime = abstime;
}
}
/* Timeout settings.*/
otp->timeout = abstime - nil.lasttime;
}
#else
/* Timeout settings.*/
otp->timeout = timeout;
#endif
/* Scanning the whole threads array.*/
ntp = nil.threads;
while (true) {
/* Is this thread ready to execute?*/
if (NIL_THD_IS_READY(ntp)) {
nil.current = nil.next = ntp;
#if defined(NIL_CFG_IDLE_ENTER_HOOK)
if (ntp == &nil.threads[NIL_CFG_NUM_THREADS]) {
NIL_CFG_IDLE_ENTER_HOOK();
}
#endif
port_switch(ntp, otp);
return nil.current->u1.msg;
}
/* Points to the next thread in lowering priority order.*/
ntp++;
chDbgAssert(ntp <= &nil.threads[NIL_CFG_NUM_THREADS],
"pointer out of range");
}
}
/**
* @brief Sends the current thread sleeping and sets a reference variable.
* @note This function must reschedule, it can only be called from thread
* context.
*
* @param[in] trp a pointer to a thread reference object
* @param[in] timeout the number of ticks before the operation timeouts,
* the following special values are allowed:
* - @a TIME_INFINITE no timeout.
* .
* @return The wake up message.
*
* @sclass
*/
msg_t chThdSuspendTimeoutS(thread_reference_t *trp, systime_t timeout) {
chDbgAssert(*trp == NULL, "not NULL");
*trp = nil.current;
nil.current->u1.trp = trp;
return chSchGoSleepTimeoutS(NIL_STATE_SUSP, timeout);
}
/**
* @brief Wakes up a thread waiting on a thread reference object.
* @note This function must not reschedule because it can be called from
* ISR context.
*
* @param[in] trp a pointer to a thread reference object
* @param[in] msg the message code
*
* @iclass
*/
void chThdResumeI(thread_reference_t *trp, msg_t msg) {
if (*trp != NULL) {
thread_reference_t tr = *trp;
chDbgAssert(NIL_THD_IS_SUSP(tr), "not suspended");
*trp = NULL;
chSchReadyI(tr, msg);
}
}
/**
* @brief Suspends the invoking thread for the specified time.
*
* @param[in] time the delay in system ticks
*
* @api
*/
void chThdSleep(systime_t time) {
chSysLock();
chThdSleepS(time);
chSysUnlock();
}
/**
* @brief Suspends the invoking thread until the system time arrives to the
* specified value.
*
* @param[in] time absolute system time
*
* @api
*/
void chThdSleepUntil(systime_t time) {
chSysLock();
chThdSleepUntilS(time);
chSysUnlock();
}
/**
* @brief Performs a wait operation on a semaphore with timeout specification.
*
* @param[in] sp pointer to a @p semaphore_t structure
* @param[in] timeout the number of ticks before the operation timeouts,
* the following special values are allowed:
* - @a TIME_IMMEDIATE immediate timeout.
* - @a TIME_INFINITE no timeout.
* .
* @return A message specifying how the invoking thread has been
* released from the semaphore.
* @retval NIL_MSG_OK if the thread has not stopped on the semaphore or the
* semaphore has been signaled.
* @retval NIL_MSG_RST if the semaphore has been reset using @p chSemReset().
* @retval NIL_MSG_TMO if the semaphore has not been signaled or reset within
* the specified timeout.
*
* @api
*/
msg_t chSemWaitTimeout(semaphore_t *sp, systime_t timeout) {
msg_t msg;
chSysLock();
msg = chSemWaitTimeoutS(sp, timeout);
chSysUnlock();
return msg;
}
/**
* @brief Performs a wait operation on a semaphore with timeout specification.
*
* @param[in] sp pointer to a @p semaphore_t structure
* @param[in] timeout the number of ticks before the operation timeouts,
* the following special values are allowed:
* - @a TIME_IMMEDIATE immediate timeout.
* - @a TIME_INFINITE no timeout.
* .
* @return A message specifying how the invoking thread has been
* released from the semaphore.
* @retval NIL_MSG_OK if the thread has not stopped on the semaphore or the
* semaphore has been signaled.
* @retval NIL_MSG_RST if the semaphore has been reset using @p chSemReset().
* @retval NIL_MSG_TMO if the semaphore has not been signaled or reset within
* the specified timeout.
*
* @sclass
*/
msg_t chSemWaitTimeoutS(semaphore_t *sp, systime_t timeout) {
/* Note, the semaphore counter is a volatile variable so accesses are
manually optimized.*/
cnt_t cnt = sp->cnt;
if (cnt <= 0) {
if (TIME_IMMEDIATE == timeout)
return MSG_TIMEOUT;
sp->cnt = cnt - 1;
nil.current->u1.semp = sp;
return chSchGoSleepTimeoutS(NIL_STATE_WTSEM, timeout);
}
sp->cnt = cnt - 1;
return MSG_OK;
}
/**
* @brief Performs a signal operation on a semaphore.
* @post This function does not reschedule so a call to a rescheduling
* function must be performed before unlocking the kernel. Note that
* interrupt handlers always reschedule on exit so an explicit
* reschedule must not be performed in ISRs.
*
* @param[in] sp pointer to a @p semaphore_t structure
*
* @api
*/
void chSemSignal(semaphore_t *sp) {
chSysLock();
chSemSignalI(sp);
chSchRescheduleS();
chSysUnlock();
}
/**
* @brief Performs a signal operation on a semaphore.
* @post This function does not reschedule so a call to a rescheduling
* function must be performed before unlocking the kernel. Note that
* interrupt handlers always reschedule on exit so an explicit
* reschedule must not be performed in ISRs.
*
* @param[in] sp pointer to a @p semaphore_t structure
*
* @iclass
*/
void chSemSignalI(semaphore_t *sp) {
if (++sp->cnt <= 0) {
thread_reference_t tr = nil.threads;
while (true) {
/* Is this thread waiting on this semaphore?*/
if (tr->u1.semp == sp) {
sp->cnt++;
chDbgAssert(NIL_THD_IS_WTSEM(tr), "not waiting");
chSchReadyI(tr, MSG_OK);
return;
}
tr++;
chDbgAssert(tr < &nil.threads[NIL_CFG_NUM_THREADS],
"pointer out of range");
}
}
}
/**
* @brief Performs a reset operation on the semaphore.
* @post After invoking this function all the threads waiting on the
* semaphore, if any, are released and the semaphore counter is set
* to the specified, non negative, value.
* @post This function does not reschedule so a call to a rescheduling
* function must be performed before unlocking the kernel. Note that
* interrupt handlers always reschedule on exit so an explicit
* reschedule must not be performed in ISRs.
*
* @param[in] sp pointer to a @p semaphore_t structure
* @param[in] n the new value of the semaphore counter. The value must
* be non-negative.
*
* @api
*/
void chSemReset(semaphore_t *sp, cnt_t n) {
chSysLock();
chSemResetI(sp, n);
chSchRescheduleS();
chSysUnlock();
}
/**
* @brief Performs a reset operation on the semaphore.
* @post After invoking this function all the threads waiting on the
* semaphore, if any, are released and the semaphore counter is set
* to the specified, non negative, value.
* @post This function does not reschedule so a call to a rescheduling
* function must be performed before unlocking the kernel. Note that
* interrupt handlers always reschedule on exit so an explicit
* reschedule must not be performed in ISRs.
*
* @param[in] sp pointer to a @p semaphore_t structure
* @param[in] n the new value of the semaphore counter. The value must
* be non-negative.
*
* @iclass
*/
void chSemResetI(semaphore_t *sp, cnt_t n) {
thread_t *tp;
cnt_t cnt;
cnt = sp->cnt;
sp->cnt = n;
tp = nil.threads;
while (cnt < 0) {
/* Is this thread waiting on this semaphore?*/
if (tp->u1.semp == sp) {
chDbgAssert(NIL_THD_IS_WTSEM(tp), "not waiting");
cnt++;
chSchReadyI(tp, MSG_RESET);
}
tp++;
chDbgAssert(tp < &nil.threads[NIL_CFG_NUM_THREADS],
"pointer out of range");
}
}
/**
* @brief Adds a set of event flags directly to the specified @p thread_t.
*
* @param[in] tp the thread to be signaled
* @param[in] mask the event flags set to be ORed
*
* @api
*/
void chEvtSignal(thread_t *tp, eventmask_t mask) {
chSysLock();
chEvtSignalI(tp, mask);
chSchRescheduleS();
chSysUnlock();
}
/**
* @brief Adds a set of event flags directly to the specified @p thread_t.
* @post This function does not reschedule so a call to a rescheduling
* function must be performed before unlocking the kernel. Note that
* interrupt handlers always reschedule on exit so an explicit
* reschedule must not be performed in ISRs.
*
* @param[in] tp the thread to be signaled
* @param[in] mask the event flags set to be ORed
*
* @iclass
*/
void chEvtSignalI(thread_t *tp, eventmask_t mask) {
tp->epmask |= mask;
if (NIL_THD_IS_WTOREVT(tp) && ((tp->epmask & tp->u1.ewmask) != 0))
chSchReadyI(tp, MSG_OK);
}
/**
* @brief Waits for any of the specified events.
* @details The function waits for any event among those specified in
* @p mask to become pending then the events are cleared and
* returned.
*
* @param[in] mask mask of the event flags that the function should wait
* for, @p ALL_EVENTS enables all the events
* @param[in] timeout the number of ticks before the operation timeouts,
* the following special values are allowed:
* - @a TIME_IMMEDIATE immediate timeout.
* - @a TIME_INFINITE no timeout.
* .
* @return The mask of the served and cleared events.
* @retval 0 if the operation has timed out.
*
* @api
*/
eventmask_t chEvtWaitAnyTimeout(eventmask_t mask, systime_t timeout) {
thread_t *ctp = nil.current;
eventmask_t m;
chSysLock();
if ((m = (ctp->epmask & mask)) == 0) {
if (TIME_IMMEDIATE == timeout) {
chSysUnlock();
return (eventmask_t)0;
}
ctp->u1.ewmask = mask;
if (chSchGoSleepTimeoutS(NIL_STATE_WTOREVT, timeout) < MSG_OK) {
chSysUnlock();
return (eventmask_t)0;
}
m = ctp->epmask & mask;
}
ctp->epmask &= ~m;
chSysUnlock();
return m;
}
/** @} */
|