/* ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010, 2011,2012 Giovanni Di Sirio. This file is part of ChibiOS/RT. ChibiOS/RT 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. ChibiOS/RT 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 . */ /** * @file chthreads.c * @brief Threads code. * * @addtogroup threads * @details Threads related APIs and services. * *

Operation mode

* A thread is an abstraction of an independent instructions flow. * In ChibiOS/RT a thread is represented by a "C" function owning * a processor context, state informations and a dedicated stack * area. In this scenario static variables are shared among all * threads while automatic variables are local to the thread.
* Operations defined for threads: * - Create, a thread is started on the specified thread * function. This operation is available in multiple variants, * both static and dynamic. * - Exit, a thread terminates by returning from its top * level function or invoking a specific API, the thread can * return a value that can be retrieved by other threads. * - Wait, a thread waits for the termination of another * thread and retrieves its return value. * - Resume, a thread created in suspended state is started. * - Sleep, the execution of a thread is suspended for the * specified amount of time or the specified future absolute time * is reached. * - SetPriority, a thread changes its own priority level. * - Yield, a thread voluntarily renounces to its time slot. * . * The threads subsystem is implicitly included in kernel however * some of its part may be excluded by disabling them in @p chconf.h, * see the @p CH_USE_WAITEXIT and @p CH_USE_DYNAMIC configuration * options. * @{ */ #include "ch.h" /** * @brief Initializes a thread structure. * @note This is an internal functions, do not use it in application code. * * @param[in] tp pointer to the thread * @param[in] prio the priority level for the new thread * @return The same thread pointer passed as parameter. * * @notapi */ Thread *_thread_init(Thread *tp, tprio_t prio) { tp->p_prio = prio; tp->p_state = THD_STATE_SUSPENDED; tp->p_flags = THD_MEM_MODE_STATIC; #if CH_TIME_QUANTUM > 0 tp->p_preempt = CH_TIME_QUANTUM; #endif #if CH_USE_MUTEXES tp->p_realprio = prio; tp->p_mtxlist = NULL; #endif #if CH_USE_EVENTS tp->p_epending = 0; #endif #if CH_DBG_THREADS_PROFILING tp->p_time = 0; #endif #if CH_USE_DYNAMIC tp->p_refs = 1; #endif #if CH_USE_REGISTRY tp->p_name = NULL; REG_INSERT(tp); #endif #if CH_USE_WAITEXIT list_init(&tp->p_waiting); #endif #if CH_USE_MESSAGES queue_init(&tp->p_msgqueue); #endif #if CH_DBG_ENABLE_STACK_CHECK tp->p_stklimit = (stkalign_t *)(tp + 1); #endif #if defined(THREAD_EXT_INIT_HOOK) THREAD_EXT_INIT_HOOK(tp); #endif return tp; } #if CH_DBG_FILL_THREADS || defined(__DOXYGEN__) /** * @brief Memory fill utility. * * @param[in] startp first address to fill * @param[in] endp last address to fill +1 * @param[in] v filler value * * @notapi */ void _thread_memfill(uint8_t *startp, uint8_t *endp, uint8_t v) { while (startp < endp) *startp++ = v; } #endif /* CH_DBG_FILL_THREADS */ /** * @brief Creates a new thread into a static memory area. * @details The new thread is initialized but not inserted in the ready list, * the initial state is @p THD_STATE_SUSPENDED. * @post The initialized thread can be subsequently started by invoking * @p chThdResume(), @p chThdResumeI() or @p chSchWakeupS() * depending on the execution context. * @note A thread can terminate by calling @p chThdExit() or by simply * returning from its main function. * @note Threads created using this function do not obey to the * @p CH_DBG_FILL_THREADS debug option because it would keep * the kernel locked for too much time. * * @param[out] wsp pointer to a working area dedicated to the thread stack * @param[in] size size of the working area * @param[in] prio the priority level for the new thread * @param[in] pf the thread function * @param[in] arg an argument passed to the thread function. It can be * @p NULL. * @return The pointer to the @p Thread structure allocated for * the thread into the working space area. * * @iclass */ Thread *chThdCreateI(void *wsp, size_t size, tprio_t prio, tfunc_t pf, void *arg) { /* Thread structure is layed out in the lower part of the thread workspace.*/ Thread *tp = wsp; chDbgCheckClassI(); chDbgCheck((wsp != NULL) && (size >= THD_WA_SIZE(0)) && (prio <= HIGHPRIO) && (pf != NULL), "chThdCreateI"); SETUP_CONTEXT(wsp, size, pf, arg); return _thread_init(tp, prio); } /** * @brief Creates a new thread into a static memory area. * @note A thread can terminate by calling @p chThdExit() or by simply * returning from its main function. * * @param[out] wsp pointer to a working area dedicated to the thread stack * @param[in] size size of the working area * @param[in] prio the priority level for the new thread * @param[in] pf the thread function * @param[in] arg an argument passed to the thread function. It can be * @p NULL. * @return The pointer to the @p Thread structure allocated for * the thread into the working space area. * * @api */ Thread *chThdCreateStatic(void *wsp, size_t size, tprio_t prio, tfunc_t pf, void *arg) { Thread *tp; #if CH_DBG_FILL_THREADS _thread_memfill((uint8_t *)wsp, (uint8_t *)wsp + sizeof(Thread), CH_THREAD_FILL_VALUE); _thread_memfill((uint8_t *)wsp + sizeof(Thread), (uint8_t *)wsp + size, CH_STACK_FILL_VALUE); #endif chSysLock(); chSchWakeupS(tp = chThdCreateI(wsp, size, prio, pf, arg), RDY_OK); chSysUnlock(); return tp; } /** * @brief Changes the running thread priority level then reschedules if * necessary. * @note The function returns the real thread priority regardless of the * current priority that could be higher than the real priority * because the priority inheritance mechanism. * * @param[in] newprio the new priority level of the running thread * @return The old priority level. * * @api */ tprio_t chThdSetPriority(tprio_t newprio) { tprio_t oldprio; chDbgCheck(newprio <= HIGHPRIO, "chThdSetPriority"); chSysLock(); #if CH_USE_MUTEXES oldprio = currp->p_realprio; if ((currp->p_prio == currp->p_realprio) || (newprio > currp->p_prio)) currp->p_prio = newprio; currp->p_realprio = newprio; #else oldprio = currp->p_prio; currp->p_prio = newprio; #endif chSchRescheduleS(); chSysUnlock(); return oldprio; } /** * @brief Resumes a suspended thread. * @pre The specified thread pointer must refer to an initialized thread * in the @p THD_STATE_SUSPENDED state. * @post The specified thread is immediately started or put in the ready * list depending on the relative priority levels. * @note Use this function to start threads created with @p chThdInit(). * * @param[in] tp pointer to the thread * @return The pointer to the thread. * * @api */ Thread *chThdResume(Thread *tp) { chSysLock(); chDbgAssert(tp->p_state == THD_STATE_SUSPENDED, "chThdResume(), #1", "thread not in THD_STATE_SUSPENDED state"); chSchWakeupS(tp, RDY_OK); chSysUnlock(); return tp; } /** * @brief Requests a thread termination. * @pre The target thread must be written to invoke periodically * @p chThdShouldTerminate() and terminate cleanly if it returns * @p TRUE. * @post The specified thread will terminate after detecting the termination * condition. * * @param[in] tp pointer to the thread * * @api */ void chThdTerminate(Thread *tp) { chSysLock(); tp->p_flags |= THD_TERMINATE; chSysUnlock(); } /** * @brief Suspends the invoking thread for the specified time. * * @param[in] time the delay in system ticks, the special values are * handled as follow: * - @a TIME_INFINITE the thread enters an infinite sleep * state. * - @a TIME_IMMEDIATE this value is not allowed. * . * * @api */ void chThdSleep(systime_t time) { chDbgCheck(time != TIME_IMMEDIATE, "chThdSleep"); 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(); if ((time -= chTimeNow()) > 0) chThdSleepS(time); chSysUnlock(); } /** * @brief Yields the time slot. * @details Yields the CPU control to the next thread in the ready list with * equal priority, if any. * * @api */ void chThdYield(void) { chSysLock(); chSchDoYieldS(); chSysUnlock(); } /** * @brief Terminates the current thread. * @details The thread goes in the @p THD_STATE_FINAL state holding the * specified exit status code, other threads can retrieve the * exit status code by invoking the function @p chThdWait(). * @post Eventual code after this function will never be executed, * this function never returns. The compiler has no way to * know this so do not assume that the compiler would remove * the dead code. * * @param[in] msg thread exit code * * @api */ void chThdExit(msg_t msg) { chSysLock(); chThdExitS(msg); /* The thread never returns here.*/ } /** * @brief Terminates the current thread. * @details The thread goes in the @p THD_STATE_FINAL state holding the * specified exit status code, other threads can retrieve the * exit status code by invoking the function @p chThdWait(). * @post Eventual code after this function will never be executed, * this function never returns. The compiler has no way to * know this so do not assume that the compiler would remove * the dead code. * * @param[in] msg thread exit code * * @sclass */ void chThdExitS(msg_t msg) { Thread *tp = currp; tp->p_u.exitcode = msg; #if defined(THREAD_EXT_EXIT_HOOK) THREAD_EXT_EXIT_HOOK(tp); #endif #if CH_USE_WAITEXIT while (notempty(&tp->p_waiting)) chSchReadyI(list_remove(&tp->p_waiting)); #endif #if CH_USE_REGISTRY /* Static threads are immediately removed from the registry because there is no memory to recover.*/ if ((tp->p_flags & THD_MEM_MODE_MASK) == THD_MEM_MODE_STATIC) REG_REMOVE(tp); #endif chSchGoSleepS(THD_STATE_FINAL); /* The thread never returns here.*/ chDbgAssert(FALSE, "chThdExitS(), #1", "zombies apocalypse"); } #if CH_USE_WAITEXIT || defined(__DOXYGEN__) /** * @brief Blocks the execution of the invoking thread until the specified * thread terminates then the exit code is returned. * @details This function waits for the specified thread to terminate then * decrements its reference counter, if the counter reaches zero then * the thread working area is returned to the proper allocator.
* The memory used by the exited thread is handled in different ways * depending on the API that spawned the thread: * - If the thread was spawned by @p chThdCreateStatic() or by * @p chThdInit() then nothing happens and the thread working area * is not released or modified in any way. This is the default, * totally static, behavior. * - If the thread was spawned by @p chThdCreateFromHeap() then * the working area is returned to the system heap. * - If the thread was spawned by @p chThdCreateFromMemoryPool() * then the working area is returned to the owning memory pool. * . * @pre The configuration option @p CH_USE_WAITEXIT must be enabled in * order to use this function. * @post Enabling @p chThdWait() requires 2-4 (depending on the * architecture) extra bytes in the @p Thread structure. * @post After invoking @p chThdWait() the thread pointer becomes invalid * and must not be used as parameter for further system calls. * @note If @p CH_USE_DYNAMIC is not specified this function just waits for * the thread termination, no memory allocators are involved. * * @param[in] tp pointer to the thread * @return The exit code from the terminated thread. * * @api */ msg_t chThdWait(Thread *tp) { msg_t msg; chDbgCheck(tp != NULL, "chThdWait"); chSysLock(); chDbgAssert(tp != currp, "chThdWait(), #1", "waiting self"); #if CH_USE_DYNAMIC chDbgAssert(tp->p_refs > 0, "chThdWait(), #2", "not referenced"); #endif if (tp->p_state != THD_STATE_FINAL) { list_insert(currp, &tp->p_waiting); chSchGoSleepS(THD_STATE_WTEXIT); } msg = tp->p_u.exitcode; chSysUnlock(); #if CH_USE_DYNAMIC chThdRelease(tp); #endif return msg; } #endif /* CH_USE_WAITEXIT */ /** @} */ '>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