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   1 /*
   2  * Copyright © 2009 Keith Packard <keithp@keithp.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; version 2 of the License.
   7  *
   8  * This program is distributed in the hope that it will be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  16  */
  17
  18 #include <ao.h>
  19 #include <ao_task.h>
  20 #if HAS_SAMPLE_PROFILE
  21 #include <ao_sample_profile.h>
  22 #endif
  23 #if HAS_STACK_GUARD
  24 #include <ao_mpu.h>
  25 #endif
  26
  27 #define DEBUG   0
  28
  29 #define AO_NO_TASK_INDEX        0xff
  30
  31 __xdata struct ao_task * __xdata ao_tasks[AO_NUM_TASKS];
  32 __data uint8_t ao_num_tasks;
  33 __xdata struct ao_task *__data ao_cur_task;
  34
  35 #if !HAS_TASK_QUEUE
  36 static __data uint8_t ao_cur_task_index;
  37 #endif
  38
  39 #ifdef ao_arch_task_globals
  40 ao_arch_task_globals
  41 #endif
  42
  43 #define AO_CHECK_STACK  0
  44
  45 #if AO_CHECK_STACK
  46 static uint8_t  in_yield;
  47
  48 static inline void ao_check_stack(void) {
  49         uint8_t q;
  50         if (!in_yield && ao_cur_task && &q < &ao_cur_task->stack[0])
  51                 ao_panic(AO_PANIC_STACK);
  52 }
  53 #else
  54 #define ao_check_stack()
  55 #endif
  56
  57 #if HAS_TASK_QUEUE
  58
  59 #define SLEEP_HASH_SIZE 17
  60
  61 static struct ao_list   run_queue;
  62 static struct ao_list   alarm_queue;
  63 static struct ao_list   sleep_queue[SLEEP_HASH_SIZE];
  64
  65 static void
  66 ao_task_to_run_queue(struct ao_task *task)
  67 {
  68         ao_list_del(&task->queue);
  69         ao_list_append(&task->queue, &run_queue);
  70 }
  71
  72 static struct ao_list *
  73 ao_task_sleep_queue(void *wchan)
  74 {
  75         return &sleep_queue[(uintptr_t) wchan % SLEEP_HASH_SIZE];
  76 }
  77
  78 static void
  79 ao_task_to_sleep_queue(struct ao_task *task, void *wchan)
  80 {
  81         ao_list_del(&task->queue);
  82         ao_list_append(&task->queue, ao_task_sleep_queue(wchan));
  83 }
  84
  85 #if DEBUG
  86 static void
  87 ao_task_validate_alarm_queue(void)
  88 {
  89         struct ao_task  *alarm, *prev = NULL;
  90         int             i;
  91
  92         if (ao_list_is_empty(&alarm_queue))
  93                 return;
  94         ao_list_for_each_entry(alarm, &alarm_queue, struct ao_task, alarm_queue) {
  95                 if (prev) {
  96                         if ((int16_t) (alarm->alarm - prev->alarm) < 0) {
  97                                 ao_panic(1);
  98                         }
  99                 }
 100                 prev = alarm;
 101         }
 102         for (i = 0; i < ao_num_tasks; i++) {
 103                 alarm = ao_tasks[i];
 104                 if (alarm->alarm) {
 105                         if (ao_list_is_empty(&alarm->alarm_queue))
 106                                 ao_panic(2);
 107                 } else {
 108                         if (!ao_list_is_empty(&alarm->alarm_queue))
 109                                 ao_panic(3);
 110                 }
 111         }
 112         if (ao_task_alarm_tick != ao_list_first_entry(&alarm_queue, struct ao_task, alarm_queue)->alarm)
 113                 ao_panic(4);
 114 }
 115 #else
 116 #define ao_task_validate_alarm_queue()
 117 #endif
 118
 119 uint16_t        ao_task_alarm_tick;
 120
 121 static void
 122 ao_task_to_alarm_queue(struct ao_task *task)
 123 {
 124         struct ao_task  *alarm;
 125         ao_list_for_each_entry(alarm, &alarm_queue, struct ao_task, alarm_queue) {
 126                 if ((int16_t) (alarm->alarm - task->alarm) >= 0) {
 127                         ao_list_insert(&task->alarm_queue, alarm->alarm_queue.prev);
 128                         ao_task_alarm_tick = ao_list_first_entry(&alarm_queue, struct ao_task, alarm_queue)->alarm;
 129                         ao_task_validate_alarm_queue();
 130                         return;
 131                 }
 132         }
 133         ao_list_append(&task->alarm_queue, &alarm_queue);
 134         ao_task_alarm_tick = ao_list_first_entry(&alarm_queue, struct ao_task, alarm_queue)->alarm;
 135         ao_task_validate_alarm_queue();
 136 }
 137
 138 static void
 139 ao_task_from_alarm_queue(struct ao_task *task)
 140 {
 141         ao_list_del(&task->alarm_queue);
 142         if (ao_list_is_empty(&alarm_queue))
 143                 ao_task_alarm_tick = 0;
 144         else
 145                 ao_task_alarm_tick = ao_list_first_entry(&alarm_queue, struct ao_task, alarm_queue)->alarm;
 146         ao_task_validate_alarm_queue();
 147 }
 148
 149 static void
 150 ao_task_init_queue(struct ao_task *task)
 151 {
 152         ao_list_init(&task->queue);
 153         ao_list_init(&task->alarm_queue);
 154 }
 155
 156 static void
 157 ao_task_exit_queue(struct ao_task *task)
 158 {
 159         ao_list_del(&task->queue);
 160         ao_list_del(&task->alarm_queue);
 161 }
 162
 163 void
 164 ao_task_check_alarm(uint16_t tick)
 165 {
 166         struct ao_task  *alarm, *next;
 167
 168         ao_list_for_each_entry_safe(alarm, next, &alarm_queue, struct ao_task, alarm_queue) {
 169                 if ((int16_t) (tick - alarm->alarm) < 0)
 170                         break;
 171                 alarm->alarm = 0;
 172                 ao_task_from_alarm_queue(alarm);
 173                 ao_task_to_run_queue(alarm);
 174         }
 175 }
 176
 177 void
 178 ao_task_init(void)
 179 {
 180         uint8_t i;
 181         ao_list_init(&run_queue);
 182         ao_list_init(&alarm_queue);
 183         ao_task_alarm_tick = 0;
 184         for (i = 0; i < SLEEP_HASH_SIZE; i++)
 185                 ao_list_init(&sleep_queue[i]);
 186 }
 187
 188 #if DEBUG
 189 static uint8_t
 190 ao_task_validate_queue(struct ao_task *task)
 191 {
 192         uint32_t flags;
 193         struct ao_task *m;
 194         uint8_t ret = 0;
 195         struct ao_list *queue;
 196
 197         flags = ao_arch_irqsave();
 198         if (task->wchan) {
 199                 queue = ao_task_sleep_queue(task->wchan);
 200                 ret |= 2;
 201         } else {
 202                 queue = &run_queue;
 203                 ret |= 4;
 204         }
 205         ao_list_for_each_entry(m, queue, struct ao_task, queue) {
 206                 if (m == task) {
 207                         ret |= 1;
 208                         break;
 209                 }
 210         }
 211         ao_arch_irqrestore(flags);
 212         return ret;
 213 }
 214
 215 static uint8_t
 216 ao_task_validate_alarm(struct ao_task *task)
 217 {
 218         uint32_t        flags;
 219         struct ao_task  *m;
 220         uint8_t         ret = 0;
 221
 222         flags = ao_arch_irqsave();
 223         if (task->alarm == 0)
 224                 return 0xff;
 225         ao_list_for_each_entry(m, &alarm_queue, struct ao_task, alarm_queue) {
 226                 if (m == task)
 227                         ret |= 1;
 228                 else {
 229                         if (!(ret&1)) {
 230                                 if ((int16_t) (m->alarm - task->alarm) > 0)
 231                                         ret |= 2;
 232                         } else {
 233                                 if ((int16_t) (task->alarm - m->alarm) > 0)
 234                                         ret |= 4;
 235                         }
 236                 }
 237         }
 238         ao_arch_irqrestore(flags);
 239         return ret;
 240 }
 241
 242
 243 static void
 244 ao_task_validate(void)
 245 {
 246         uint8_t         i;
 247         struct ao_task  *task;
 248         uint8_t         ret;
 249
 250         for (i = 0; i < ao_num_tasks; i++) {
 251                 task = ao_tasks[i];
 252                 ret = ao_task_validate_queue(task);
 253                 if (!(ret & 1)) {
 254                         if (ret & 2)
 255                                 printf ("sleeping task not on sleep queue %s %08x\n",
 256                                         task->name, task->wchan);
 257                         else
 258                                 printf ("running task not on run queue %s\n",
 259                                         task->name);
 260                 }
 261                 ret = ao_task_validate_alarm(task);
 262                 if (ret != 0xff) {
 263                         if (!(ret & 1))
 264                                 printf ("alarm task not on alarm queue %s %d\n",
 265                                         task->name, task->alarm);
 266                         if (ret & 2)
 267                                 printf ("alarm queue has sooner entries after %s %d\n",
 268                                         task->name, task->alarm);
 269                         if (ret & 4)
 270                                 printf ("alarm queue has later entries before %s %d\n",
 271                                         task->name, task->alarm);
 272                 }
 273         }
 274 }
 275 #endif /* DEBUG */
 276
 277 #endif /* HAS_TASK_QUEUE */
 278
 279 void
 280 ao_add_task(__xdata struct ao_task * task, void (*start)(void), __code char *name) __reentrant
 281 {
 282         uint8_t task_id;
 283         uint8_t t;
 284         if (ao_num_tasks == AO_NUM_TASKS)
 285                 ao_panic(AO_PANIC_NO_TASK);
 286         for (task_id = 1; task_id != 0; task_id++) {
 287                 for (t = 0; t < ao_num_tasks; t++)
 288                         if (ao_tasks[t]->task_id == task_id)
 289                                 break;
 290                 if (t == ao_num_tasks)
 291                         break;
 292         }
 293         task->task_id = task_id;
 294         task->name = name;
 295         task->wchan = NULL;
 296         /*
 297          * Construct a stack frame so that it will 'return'
 298          * to the start of the task
 299          */
 300         ao_arch_init_stack(task, start);
 301         ao_arch_critical(
 302 #if HAS_TASK_QUEUE
 303                 ao_task_init_queue(task);
 304                 ao_task_to_run_queue(task);
 305 #endif
 306                 ao_tasks[ao_num_tasks] = task;
 307                 ao_num_tasks++;
 308                 );
 309 }
 310
 311 __data uint8_t  ao_task_minimize_latency;
 312
 313 /* Task switching function. This must not use any stack variables */
 314 void
 315 ao_yield(void) ao_arch_naked_define
 316 {
 317         ao_arch_save_regs();
 318
 319 #if HAS_TASK_QUEUE
 320         if (ao_cur_task == NULL)
 321                 ao_cur_task = ao_tasks[ao_num_tasks-1];
 322 #else
 323         if (ao_cur_task_index == AO_NO_TASK_INDEX)
 324                 ao_cur_task_index = ao_num_tasks-1;
 325 #endif
 326         else
 327         {
 328 #if HAS_SAMPLE_PROFILE
 329                 uint16_t        tick = ao_sample_profile_timer_value();
 330                 uint16_t        run = tick - ao_cur_task->start;
 331                 if (run > ao_cur_task->max_run)
 332                         ao_cur_task->max_run = run;
 333                 ++ao_cur_task->yields;
 334 #endif
 335                 ao_arch_save_stack();
 336         }
 337
 338         ao_arch_isr_stack();
 339 #if !HAS_TASK_QUEUE
 340         if (ao_task_minimize_latency)
 341                 ao_arch_release_interrupts();
 342         else
 343 #endif
 344                 ao_arch_block_interrupts();
 345
 346 #if AO_CHECK_STACK
 347         in_yield = 1;
 348 #endif
 349         /* Find a task to run. If there isn't any runnable task,
 350          * this loop will run forever, which is just fine
 351          */
 352 #if HAS_TASK_QUEUE
 353         /* If the current task is running, move it to the
 354          * end of the queue to allow other tasks a chance
 355          */
 356         if (ao_cur_task->wchan == NULL)
 357                 ao_task_to_run_queue(ao_cur_task);
 358         for (;;) {
 359                 ao_arch_memory_barrier();
 360                 if (!ao_list_is_empty(&run_queue))
 361                         break;
 362                 /* Wait for interrupts when there's nothing ready */
 363                 ao_arch_wait_interrupt();
 364         }
 365         ao_cur_task = ao_list_first_entry(&run_queue, struct ao_task, queue);
 366 #else
 367         {
 368                 __pdata uint8_t ao_last_task_index = ao_cur_task_index;
 369                 for (;;) {
 370                         ++ao_cur_task_index;
 371                         if (ao_cur_task_index == ao_num_tasks)
 372                                 ao_cur_task_index = 0;
 373
 374                         ao_cur_task = ao_tasks[ao_cur_task_index];
 375
 376                         /* Check for ready task */
 377                         if (ao_cur_task->wchan == NULL)
 378                                 break;
 379
 380                         /* Check if the alarm is set for a time which has passed */
 381                         if (ao_cur_task->alarm &&
 382                             (int16_t) (ao_time() - ao_cur_task->alarm) >= 0)
 383                                 break;
 384
 385                         /* Wait for interrupts when there's nothing ready */
 386                         if (ao_cur_task_index == ao_last_task_index && !ao_task_minimize_latency)
 387                                 ao_arch_wait_interrupt();
 388                 }
 389         }
 390 #endif
 391 #if HAS_SAMPLE_PROFILE
 392         ao_cur_task->start = ao_sample_profile_timer_value();
 393 #endif
 394 #if HAS_STACK_GUARD
 395         ao_mpu_stack_guard(ao_cur_task->stack);
 396 #endif
 397 #if AO_CHECK_STACK
 398         in_yield = 0;
 399 #endif
 400         ao_arch_restore_stack();
 401 }
 402
 403 uint8_t
 404 ao_sleep(__xdata void *wchan)
 405 {
 406 #if HAS_TASK_QUEUE
 407         uint32_t flags;
 408         flags = ao_arch_irqsave();
 409 #endif
 410         ao_cur_task->wchan = wchan;
 411 #if HAS_TASK_QUEUE
 412         ao_task_to_sleep_queue(ao_cur_task, wchan);
 413         ao_arch_irqrestore(flags);
 414 #endif
 415         ao_yield();
 416         if (ao_cur_task->wchan) {
 417                 ao_cur_task->wchan = NULL;
 418                 ao_cur_task->alarm = 0;
 419                 return 1;
 420         }
 421         return 0;
 422 }
 423
 424 void
 425 ao_wakeup(__xdata void *wchan) __reentrant
 426 {
 427         ao_validate_cur_stack();
 428 #if HAS_TASK_QUEUE
 429         struct ao_task  *sleep, *next;
 430         struct ao_list  *sleep_queue;
 431         uint32_t        flags;
 432
 433         if (ao_num_tasks == 0)
 434                 return;
 435         sleep_queue = ao_task_sleep_queue(wchan);
 436         flags = ao_arch_irqsave();
 437         ao_list_for_each_entry_safe(sleep, next, sleep_queue, struct ao_task, queue) {
 438                 if (sleep->wchan == wchan) {
 439                         sleep->wchan = NULL;
 440                         ao_task_to_run_queue(sleep);
 441                 }
 442         }
 443         ao_arch_irqrestore(flags);
 444 #else
 445         {
 446         uint8_t i;
 447         for (i = 0; i < ao_num_tasks; i++)
 448                 if (ao_tasks[i]->wchan == wchan)
 449                         ao_tasks[i]->wchan = NULL;
 450         }
 451 #endif
 452         ao_check_stack();
 453 }
 454
 455 uint8_t
 456 ao_sleep_for(__xdata void *wchan, uint16_t timeout)
 457 {
 458         uint8_t ret;
 459         if (timeout) {
 460 #if HAS_TASK_QUEUE
 461                 uint32_t flags;
 462                 /* Make sure we sleep *at least* delay ticks, which means adding
 463                  * one to account for the fact that we may be close to the next tick
 464                  */
 465                 flags = ao_arch_irqsave();
 466 #endif
 467                 if (!(ao_cur_task->alarm = ao_time() + timeout + 1))
 468                         ao_cur_task->alarm = 1;
 469 #if HAS_TASK_QUEUE
 470                 ao_task_to_alarm_queue(ao_cur_task);
 471                 ao_arch_irqrestore(flags);
 472 #endif
 473         }
 474         ret = ao_sleep(wchan);
 475         if (timeout) {
 476 #if HAS_TASK_QUEUE
 477                 uint32_t flags;
 478
 479                 flags = ao_arch_irqsave();
 480 #endif
 481                 ao_cur_task->alarm = 0;
 482 #if HAS_TASK_QUEUE
 483                 ao_task_from_alarm_queue(ao_cur_task);
 484                 ao_arch_irqrestore(flags);
 485 #endif
 486         }
 487         return ret;
 488 }
 489
 490 static __xdata uint8_t ao_forever;
 491
 492 void
 493 ao_delay(uint16_t ticks)
 494 {
 495         ao_sleep_for(&ao_forever, ticks);
 496 }
 497
 498 void
 499 ao_exit(void)
 500 {
 501         uint8_t i;
 502         ao_arch_block_interrupts();
 503         ao_num_tasks--;
 504 #if HAS_TASK_QUEUE
 505         for (i = 0; i < ao_num_tasks; i++)
 506                 if (ao_tasks[i] == ao_cur_task)
 507                         break;
 508         ao_task_exit_queue(ao_cur_task);
 509 #else
 510         i = ao_cur_task_index;
 511         ao_cur_task_index = AO_NO_TASK_INDEX;
 512 #endif
 513         for (; i < ao_num_tasks; i++)
 514                 ao_tasks[i] = ao_tasks[i+1];
 515         ao_cur_task = NULL;
 516         ao_yield();
 517         /* we'll never get back here */
 518 }
 519
 520 #if HAS_TASK_INFO
 521 void
 522 ao_task_info(void)
 523 {
 524         uint8_t         i;
 525         __xdata struct ao_task *task;
 526
 527         for (i = 0; i < ao_num_tasks; i++) {
 528                 task = ao_tasks[i];
 529                 printf("%12s: wchan %04x\n",
 530                        task->name,
 531                        (int) task->wchan);
 532         }
 533 #if HAS_TASK_QUEUE && DEBUG
 534         ao_task_validate();
 535 #endif
 536 }
 537 #endif
 538
 539 void
 540 ao_start_scheduler(void)
 541 {
 542 #if !HAS_TASK_QUEUE
 543         ao_cur_task_index = AO_NO_TASK_INDEX;
 544 #endif
 545         ao_cur_task = NULL;
 546 #if HAS_ARCH_START_SCHEDULER
 547         ao_arch_start_scheduler();
 548 #endif
 549         ao_yield();
 550 }