src/os2/thread.c

   1 /*****************************************************************************
   2  * thread.c : OS/2 back-end for LibVLC
   3  *****************************************************************************
   4  * Copyright (C) 1999-2011 VLC authors and VideoLAN
   5  *
   6  * Authors: KO Myung-Hun <komh@chollian.net>
   7  *          Jean-Marc Dressler <polux@via.ecp.fr>
   8  *          Samuel Hocevar <sam@zoy.org>
   9  *          Gildas Bazin <gbazin@netcourrier.com>
  10  *          Clément Sténac
  11  *          Rémi Denis-Courmont
  12  *          Pierre Ynard
  13  *
  14  * This program is free software; you can redistribute it and/or modify it
  15  * under the terms of the GNU Lesser General Public License as published by
  16  * the Free Software Foundation; either version 2.1 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * This program is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  22  * GNU Lesser General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU Lesser General Public License
  25  * along with this program; if not, write to the Free Software Foundation,
  26  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  27  *****************************************************************************/
  28
  29 #ifdef HAVE_CONFIG_H
  30 # include "config.h"
  31 #endif
  32
  33 #include <vlc_common.h>
  34
  35 #include "libvlc.h"
  36 #include <stdarg.h>
  37 #include <assert.h>
  38 #include <limits.h>
  39 #include <errno.h>
  40 #include <time.h>
  41
  42 static vlc_threadvar_t thread_key;
  43
  44 /**
  45  * Per-thread data
  46  */
  47 struct vlc_thread
  48 {
  49     TID            tid;
  50     HEV            cancel_event;
  51     HEV            done_event;
  52
  53     bool           detached;
  54     bool           killable;
  55     bool           killed;
  56     vlc_cleanup_t *cleaners;
  57
  58     void        *(*entry) (void *);
  59     void          *data;
  60 };
  61
  62 static void vlc_cancel_self (PVOID dummy);
  63
  64 static ULONG vlc_DosWaitEventSemEx( HEV hev, ULONG ulTimeout, BOOL fCancelable )
  65 {
  66     HMUX      hmux;
  67     SEMRECORD asr[ 2 ];
  68     ULONG     ulUser;
  69     int       n;
  70     ULONG     rc;
  71
  72     struct vlc_thread *th = vlc_threadvar_get( thread_key );
  73     if( th == NULL || !fCancelable )
  74     {
  75         /* Main thread - cannot be cancelled anyway
  76          * Alien thread - out of our control
  77          */
  78         if( hev != NULLHANDLE )
  79             return DosWaitEventSem( hev, ulTimeout );
  80
  81         return DosSleep( ulTimeout );
  82     }
  83
  84     n = 0;
  85     if( hev != NULLHANDLE )
  86     {
  87         asr[ n ].hsemCur = ( HSEM )hev;
  88         asr[ n ].ulUser  = 0;
  89         n++;
  90     }
  91     asr[ n ].hsemCur = ( HSEM )th->cancel_event;
  92     asr[ n ].ulUser  = 0xFFFF;
  93     n++;
  94
  95     DosCreateMuxWaitSem( NULL, &hmux, n, asr, DCMW_WAIT_ANY );
  96     rc = DosWaitMuxWaitSem( hmux, ulTimeout, &ulUser );
  97     DosCloseMuxWaitSem( hmux );
  98     if( rc )
  99         return rc;
 100
 101     if( ulUser == 0xFFFF )
 102     {
 103         vlc_cancel_self( th );
 104         return ERROR_INTERRUPT;
 105     }
 106
 107     return NO_ERROR;
 108 }
 109
 110 static ULONG vlc_WaitForSingleObject (HEV hev, ULONG ulTimeout)
 111 {
 112     return vlc_DosWaitEventSemEx( hev, ulTimeout, TRUE );
 113 }
 114
 115 static ULONG vlc_Sleep (ULONG ulTimeout)
 116 {
 117     ULONG rc = vlc_DosWaitEventSemEx( NULLHANDLE, ulTimeout, TRUE );
 118
 119     return ( rc != ERROR_TIMEOUT ) ? rc : 0;
 120 }
 121
 122 static vlc_mutex_t super_mutex;
 123 static vlc_cond_t  super_variable;
 124 extern vlc_rwlock_t config_lock, msg_lock;
 125
 126 int _CRT_init(void);
 127 void _CRT_term(void);
 128
 129 unsigned long _System _DLL_InitTerm(unsigned long, unsigned long);
 130
 131 unsigned long _System _DLL_InitTerm(unsigned long hmod, unsigned long flag)
 132 {
 133     VLC_UNUSED (hmod);
 134
 135     switch (flag)
 136     {
 137         case 0 :    /* Initialization */
 138             if(_CRT_init() == -1)
 139                 return 0;
 140
 141             vlc_mutex_init (&super_mutex);
 142             vlc_cond_init (&super_variable);
 143             vlc_threadvar_create (&thread_key, NULL);
 144             vlc_rwlock_init (&config_lock);
 145             vlc_rwlock_init (&msg_lock);
 146             vlc_CPU_init ();
 147
 148             return 1;
 149
 150         case 1 :    /* Termination */
 151             vlc_rwlock_destroy (&msg_lock);
 152             vlc_rwlock_destroy (&config_lock);
 153             vlc_threadvar_delete (&thread_key);
 154             vlc_cond_destroy (&super_variable);
 155             vlc_mutex_destroy (&super_mutex);
 156
 157             _CRT_term();
 158
 159             return 1;
 160     }
 161
 162     return 0;   /* Failed */
 163 }
 164
 165 /*** Mutexes ***/
 166 void vlc_mutex_init( vlc_mutex_t *p_mutex )
 167 {
 168     /* This creates a recursive mutex. This is OK as fast mutexes have
 169      * no defined behavior in case of recursive locking. */
 170     DosCreateMutexSem( NULL, &p_mutex->hmtx, 0, FALSE );
 171     p_mutex->dynamic = true;
 172 }
 173
 174 void vlc_mutex_init_recursive( vlc_mutex_t *p_mutex )
 175 {
 176     DosCreateMutexSem( NULL, &p_mutex->hmtx, 0, FALSE );
 177     p_mutex->dynamic = true;
 178 }
 179
 180
 181 void vlc_mutex_destroy (vlc_mutex_t *p_mutex)
 182 {
 183     assert (p_mutex->dynamic);
 184     DosCloseMutexSem( p_mutex->hmtx );
 185 }
 186
 187 void vlc_mutex_lock (vlc_mutex_t *p_mutex)
 188 {
 189     if (!p_mutex->dynamic)
 190     {   /* static mutexes */
 191         int canc = vlc_savecancel ();
 192         assert (p_mutex != &super_mutex); /* this one cannot be static */
 193
 194         vlc_mutex_lock (&super_mutex);
 195         while (p_mutex->locked)
 196         {
 197             p_mutex->contention++;
 198             vlc_cond_wait (&super_variable, &super_mutex);
 199             p_mutex->contention--;
 200         }
 201         p_mutex->locked = true;
 202         vlc_mutex_unlock (&super_mutex);
 203         vlc_restorecancel (canc);
 204         return;
 205     }
 206
 207     DosRequestMutexSem(p_mutex->hmtx, SEM_INDEFINITE_WAIT);
 208 }
 209
 210 int vlc_mutex_trylock (vlc_mutex_t *p_mutex)
 211 {
 212     if (!p_mutex->dynamic)
 213     {   /* static mutexes */
 214         int ret = EBUSY;
 215
 216         assert (p_mutex != &super_mutex); /* this one cannot be static */
 217         vlc_mutex_lock (&super_mutex);
 218         if (!p_mutex->locked)
 219         {
 220             p_mutex->locked = true;
 221             ret = 0;
 222         }
 223         vlc_mutex_unlock (&super_mutex);
 224         return ret;
 225     }
 226
 227     return DosRequestMutexSem( p_mutex->hmtx, 0 ) ? EBUSY : 0;
 228 }
 229
 230 void vlc_mutex_unlock (vlc_mutex_t *p_mutex)
 231 {
 232     if (!p_mutex->dynamic)
 233     {   /* static mutexes */
 234         assert (p_mutex != &super_mutex); /* this one cannot be static */
 235
 236         vlc_mutex_lock (&super_mutex);
 237         assert (p_mutex->locked);
 238         p_mutex->locked = false;
 239         if (p_mutex->contention)
 240             vlc_cond_broadcast (&super_variable);
 241         vlc_mutex_unlock (&super_mutex);
 242         return;
 243     }
 244
 245     DosReleaseMutexSem( p_mutex->hmtx );
 246 }
 247
 248 /*** Condition variables ***/
 249 enum
 250 {
 251     CLOCK_REALTIME=0, /* must be zero for VLC_STATIC_COND */
 252     CLOCK_MONOTONIC,
 253 };
 254
 255 static void vlc_cond_init_common (vlc_cond_t *p_condvar, unsigned clock)
 256 {
 257     /* Create a manual-reset event (manual reset is needed for broadcast). */
 258     if (DosCreateEventSem (NULL, &p_condvar->hev, 0, FALSE))
 259         abort();
 260     p_condvar->clock = clock;
 261 }
 262
 263 void vlc_cond_init (vlc_cond_t *p_condvar)
 264 {
 265     vlc_cond_init_common (p_condvar, CLOCK_MONOTONIC);
 266 }
 267
 268 void vlc_cond_init_daytime (vlc_cond_t *p_condvar)
 269 {
 270     vlc_cond_init_common (p_condvar, CLOCK_REALTIME);
 271 }
 272
 273 void vlc_cond_destroy (vlc_cond_t *p_condvar)
 274 {
 275     DosCloseEventSem( p_condvar->hev );
 276 }
 277
 278 void vlc_cond_signal (vlc_cond_t *p_condvar)
 279 {
 280     if (!p_condvar->hev)
 281         return;
 282
 283     /* This is suboptimal but works. */
 284     vlc_cond_broadcast (p_condvar);
 285 }
 286
 287 void vlc_cond_broadcast (vlc_cond_t *p_condvar)
 288 {
 289     if (!p_condvar->hev)
 290         return;
 291
 292     /* Wake all threads up (as the event HANDLE has manual reset) */
 293     DosPostEventSem( p_condvar->hev );
 294 }
 295
 296 void vlc_cond_wait (vlc_cond_t *p_condvar, vlc_mutex_t *p_mutex)
 297 {
 298     ULONG ulPost;
 299     ULONG rc;
 300
 301     if (!p_condvar->hev)
 302     {   /* FIXME FIXME FIXME */
 303         msleep (50000);
 304         return;
 305     }
 306
 307     do
 308     {
 309         vlc_testcancel();
 310
 311         vlc_mutex_unlock (p_mutex);
 312         rc = vlc_WaitForSingleObject( p_condvar->hev, SEM_INDEFINITE_WAIT );
 313         vlc_mutex_lock (p_mutex);
 314     } while( rc == ERROR_INTERRUPT );
 315
 316     DosResetEventSem( p_condvar->hev, &ulPost );
 317 }
 318
 319 int vlc_cond_timedwait (vlc_cond_t *p_condvar, vlc_mutex_t *p_mutex,
 320                         mtime_t deadline)
 321 {
 322     ULONG   ulTimeout;
 323     ULONG   ulPost;
 324     ULONG   rc;
 325
 326     if (!p_condvar->hev)
 327     {   /* FIXME FIXME FIXME */
 328         msleep (50000);
 329         return;
 330     }
 331
 332     do
 333     {
 334         vlc_testcancel();
 335
 336         mtime_t total;
 337         switch (p_condvar->clock)
 338         {
 339             case CLOCK_REALTIME: /* FIXME? sub-second precision */
 340                 total = CLOCK_FREQ * time (NULL);
 341                 break;
 342             default:
 343                 assert (p_condvar->clock == CLOCK_MONOTONIC);
 344                 total = mdate();
 345                 break;
 346         }
 347         total = (deadline - total) / 1000;
 348         if( total < 0 )
 349             total = 0;
 350
 351         ulTimeout = ( total > 0x7fffffff ) ? 0x7fffffff : total;
 352
 353         vlc_mutex_unlock (p_mutex);
 354         rc = vlc_WaitForSingleObject( p_condvar->hev, ulTimeout );
 355         vlc_mutex_lock (p_mutex);
 356     } while( rc == ERROR_INTERRUPT );
 357
 358     DosResetEventSem( p_condvar->hev, &ulPost );
 359
 360     return rc ? ETIMEDOUT : 0;
 361 }
 362
 363 /*** Thread-specific variables (TLS) ***/
 364 struct vlc_threadvar
 365 {
 366     PULONG                id;
 367     void                (*destroy) (void *);
 368     struct vlc_threadvar *prev;
 369     struct vlc_threadvar *next;
 370 } *vlc_threadvar_last = NULL;
 371
 372 int vlc_threadvar_create (vlc_threadvar_t *p_tls, void (*destr) (void *))
 373 {
 374     ULONG rc;
 375
 376     struct vlc_threadvar *var = malloc (sizeof (*var));
 377     if (unlikely(var == NULL))
 378         return errno;
 379
 380     rc = DosAllocThreadLocalMemory( 1, &var->id );
 381     if( rc )
 382     {
 383         free (var);
 384         return EAGAIN;
 385     }
 386
 387     var->destroy = destr;
 388     var->next = NULL;
 389     *p_tls = var;
 390
 391     vlc_mutex_lock (&super_mutex);
 392     var->prev = vlc_threadvar_last;
 393     vlc_threadvar_last = var;
 394     vlc_mutex_unlock (&super_mutex);
 395     return 0;
 396 }
 397
 398 void vlc_threadvar_delete (vlc_threadvar_t *p_tls)
 399 {
 400     struct vlc_threadvar *var = *p_tls;
 401
 402     vlc_mutex_lock (&super_mutex);
 403     if (var->prev != NULL)
 404         var->prev->next = var->next;
 405     else
 406         vlc_threadvar_last = var->next;
 407     if (var->next != NULL)
 408         var->next->prev = var->prev;
 409     vlc_mutex_unlock (&super_mutex);
 410
 411     DosFreeThreadLocalMemory( var->id );
 412     free (var);
 413 }
 414
 415 int vlc_threadvar_set (vlc_threadvar_t key, void *value)
 416 {
 417     *key->id = ( ULONG )value;
 418     return 0;
 419 }
 420
 421 void *vlc_threadvar_get (vlc_threadvar_t key)
 422 {
 423     return ( void * )*key->id;
 424 }
 425
 426
 427 /*** Threads ***/
 428 void vlc_threads_setup (libvlc_int_t *p_libvlc)
 429 {
 430     (void) p_libvlc;
 431 }
 432
 433 static void vlc_thread_cleanup (struct vlc_thread *th)
 434 {
 435     vlc_threadvar_t key;
 436
 437 retry:
 438     /* TODO: use RW lock or something similar */
 439     vlc_mutex_lock (&super_mutex);
 440     for (key = vlc_threadvar_last; key != NULL; key = key->prev)
 441     {
 442         void *value = vlc_threadvar_get (key);
 443         if (value != NULL && key->destroy != NULL)
 444         {
 445             vlc_mutex_unlock (&super_mutex);
 446             vlc_threadvar_set (key, NULL);
 447             key->destroy (value);
 448             goto retry;
 449         }
 450     }
 451     vlc_mutex_unlock (&super_mutex);
 452
 453     if (th->detached)
 454     {
 455         DosCloseEventSem (th->cancel_event);
 456         DosCloseEventSem (th->done_event );
 457         free (th);
 458     }
 459 }
 460
 461 static void vlc_entry( void *p )
 462 {
 463     struct vlc_thread *th = p;
 464
 465     vlc_threadvar_set (thread_key, th);
 466     th->killable = true;
 467     th->data = th->entry (th->data);
 468     DosPostEventSem( th->done_event );
 469     vlc_thread_cleanup (th);
 470 }
 471
 472 static int vlc_clone_attr (vlc_thread_t *p_handle, bool detached,
 473                            void *(*entry) (void *), void *data, int priority)
 474 {
 475     struct vlc_thread *th = malloc (sizeof (*th));
 476     if (unlikely(th == NULL))
 477         return ENOMEM;
 478     th->entry = entry;
 479     th->data = data;
 480     th->detached = detached;
 481     th->killable = false; /* not until vlc_entry() ! */
 482     th->killed = false;
 483     th->cleaners = NULL;
 484
 485     if( DosCreateEventSem (NULL, &th->cancel_event, 0, FALSE))
 486         goto error;
 487     if( DosCreateEventSem (NULL, &th->done_event, 0, FALSE))
 488         goto error;
 489
 490     th->tid = _beginthread (vlc_entry, NULL, 1024 * 1024, th);
 491     if((int)th->tid == -1)
 492         goto error;
 493
 494     if (p_handle != NULL)
 495         *p_handle = th;
 496
 497     if (priority)
 498         DosSetPriority(PRTYS_THREAD,
 499                        HIBYTE(priority),
 500                        LOBYTE(priority),
 501                        th->tid);
 502
 503     return 0;
 504
 505 error:
 506     DosCloseEventSem (th->cancel_event);
 507     DosCloseEventSem (th->done_event);
 508     free (th);
 509
 510     return ENOMEM;
 511 }
 512
 513 int vlc_clone (vlc_thread_t *p_handle, void *(*entry) (void *),
 514                 void *data, int priority)
 515 {
 516     return vlc_clone_attr (p_handle, false, entry, data, priority);
 517 }
 518
 519 void vlc_join (vlc_thread_t th, void **result)
 520 {
 521     ULONG rc;
 522
 523     do
 524     {
 525         vlc_testcancel();
 526         rc = vlc_WaitForSingleObject( th->done_event, SEM_INDEFINITE_WAIT );
 527     } while( rc == ERROR_INTERRUPT );
 528
 529     if (result != NULL)
 530         *result = th->data;
 531
 532     DosCloseEventSem( th->cancel_event );
 533     DosCloseEventSem( th->done_event );
 534
 535     free( th );
 536 }
 537
 538 int vlc_clone_detach (vlc_thread_t *p_handle, void *(*entry) (void *),
 539                       void *data, int priority)
 540 {
 541     vlc_thread_t th;
 542     if (p_handle == NULL)
 543         p_handle = &th;
 544
 545     return vlc_clone_attr (p_handle, true, entry, data, priority);
 546 }
 547
 548 int vlc_set_priority (vlc_thread_t th, int priority)
 549 {
 550     if (DosSetPriority(PRTYS_THREAD,
 551                        HIBYTE(priority),
 552                        LOBYTE(priority),
 553                        th->tid))
 554         return VLC_EGENERIC;
 555     return VLC_SUCCESS;
 556 }
 557
 558 /*** Thread cancellation ***/
 559
 560 /* APC procedure for thread cancellation */
 561 static void vlc_cancel_self (PVOID self)
 562 {
 563     struct vlc_thread *th = self;
 564
 565     if (likely(th != NULL))
 566         th->killed = true;
 567 }
 568
 569 void vlc_cancel (vlc_thread_t thread_id)
 570 {
 571     DosPostEventSem( thread_id->cancel_event );
 572 }
 573
 574 int vlc_savecancel (void)
 575 {
 576     int state;
 577
 578     struct vlc_thread *th = vlc_threadvar_get (thread_key);
 579     if (th == NULL)
 580         return false; /* Main thread - cannot be cancelled anyway */
 581
 582     state = th->killable;
 583     th->killable = false;
 584     return state;
 585 }
 586
 587 void vlc_restorecancel (int state)
 588 {
 589     struct vlc_thread *th = vlc_threadvar_get (thread_key);
 590     assert (state == false || state == true);
 591
 592     if (th == NULL)
 593         return; /* Main thread - cannot be cancelled anyway */
 594
 595     assert (!th->killable);
 596     th->killable = state != 0;
 597 }
 598
 599 void vlc_testcancel (void)
 600 {
 601     struct vlc_thread *th = vlc_threadvar_get (thread_key);
 602     if (th == NULL)
 603         return; /* Main thread - cannot be cancelled anyway */
 604
 605     /* This check is needed for the case that vlc_cancel() is followed by
 606      * vlc_testcancel() without any cancellation point */
 607     if( DosWaitEventSem( th->cancel_event, 0 ) == NO_ERROR )
 608         vlc_cancel_self( th );
 609
 610     if (th->killable && th->killed)
 611     {
 612         for (vlc_cleanup_t *p = th->cleaners; p != NULL; p = p->next)
 613              p->proc (p->data);
 614
 615         DosPostEventSem( th->done_event );
 616         th->data = NULL; /* TODO: special value? */
 617         vlc_thread_cleanup (th);
 618         _endthread();
 619     }
 620 }
 621
 622 void vlc_control_cancel (int cmd, ...)
 623 {
 624     /* NOTE: This function only modifies thread-specific data, so there is no
 625      * need to lock anything. */
 626     va_list ap;
 627
 628     struct vlc_thread *th = vlc_threadvar_get (thread_key);
 629     if (th == NULL)
 630         return; /* Main thread - cannot be cancelled anyway */
 631
 632     va_start (ap, cmd);
 633     switch (cmd)
 634     {
 635         case VLC_CLEANUP_PUSH:
 636         {
 637             /* cleaner is a pointer to the caller stack, no need to allocate
 638              * and copy anything. As a nice side effect, this cannot fail. */
 639             vlc_cleanup_t *cleaner = va_arg (ap, vlc_cleanup_t *);
 640             cleaner->next = th->cleaners;
 641             th->cleaners = cleaner;
 642             break;
 643         }
 644
 645         case VLC_CLEANUP_POP:
 646         {
 647             th->cleaners = th->cleaners->next;
 648             break;
 649         }
 650     }
 651     va_end (ap);
 652 }
 653
 654 #define Q2LL( q )   ( *( long long * )&( q ))
 655
 656 /*** Clock ***/
 657 mtime_t mdate (void)
 658 {
 659     /* We don't need the real date, just the value of a high precision timer */
 660     QWORD counter;
 661     ULONG freq;
 662     if (DosTmrQueryTime(&counter) || DosTmrQueryFreq(&freq))
 663         abort();
 664
 665     /* Convert to from (1/freq) to microsecond resolution */
 666     /* We need to split the division to avoid 63-bits overflow */
 667     lldiv_t d = lldiv (Q2LL(counter), freq);
 668
 669     return (d.quot * 1000000) + ((d.rem * 1000000) / freq);
 670 }
 671
 672 #undef mwait
 673 void mwait (mtime_t deadline)
 674 {
 675     mtime_t delay;
 676
 677     vlc_testcancel();
 678     while ((delay = (deadline - mdate())) > 0)
 679     {
 680         delay /= 1000;
 681         if (unlikely(delay > 0x7fffffff))
 682             delay = 0x7fffffff;
 683         vlc_Sleep (delay);
 684         vlc_testcancel();
 685     }
 686 }
 687
 688 #undef msleep
 689 void msleep (mtime_t delay)
 690 {
 691     mwait (mdate () + delay);
 692 }
 693
 694 /*** Timers ***/
 695 struct vlc_timer
 696 {
 697     TID    tid;
 698     HEV    hev;
 699     HTIMER htimer;
 700     ULONG  interval;
 701     bool   quit;
 702     void (*func) (void *);
 703     void  *data;
 704 };
 705
 706 static void vlc_timer_do (void *arg)
 707 {
 708     struct vlc_timer *timer = arg;
 709
 710     while (1)
 711     {
 712         ULONG count;
 713
 714         DosWaitEventSem (timer->hev, SEM_INDEFINITE_WAIT);
 715         DosResetEventSem (timer->hev, &count);
 716
 717         if (timer->quit)
 718             break;
 719
 720         timer->func (timer->data);
 721
 722         if (timer->interval)
 723             DosAsyncTimer (timer->interval, (HSEM)timer->hev, &timer->htimer);
 724     }
 725 }
 726
 727 int vlc_timer_create (vlc_timer_t *id, void (*func) (void *), void *data)
 728 {
 729     struct vlc_timer *timer = malloc (sizeof (*timer));
 730
 731     if (timer == NULL)
 732         return ENOMEM;
 733
 734     timer->func = func;
 735     timer->data = data;
 736
 737     DosCreateEventSem (NULL, &timer->hev, DC_SEM_SHARED, FALSE);
 738     timer->htimer = NULLHANDLE;
 739     timer->interval = 0;
 740     timer->quit = false;
 741     timer->tid  = _beginthread (vlc_timer_do, NULL, 1024 * 1024, timer);
 742
 743     *id = timer;
 744     return 0;
 745 }
 746
 747 void vlc_timer_destroy (vlc_timer_t timer)
 748 {
 749     if (timer->htimer != NULLHANDLE)
 750         DosStopTimer (timer->htimer);
 751
 752     timer->quit = true;
 753     DosPostEventSem (timer->hev);
 754     DosWaitThread (&timer->tid, DCWW_WAIT);
 755     DosCloseEventSem (timer->hev);
 756
 757     free (timer);
 758 }
 759
 760 void vlc_timer_schedule (vlc_timer_t timer, bool absolute,
 761                          mtime_t value, mtime_t interval)
 762 {
 763     if (timer->htimer != NULLHANDLE)
 764     {
 765         DosStopTimer (timer->htimer);
 766         timer->htimer = NULLHANDLE;
 767         timer->interval = 0;
 768     }
 769
 770     if (value == 0)
 771         return; /* Disarm */
 772
 773     if (absolute)
 774         value -= mdate ();
 775     value = (value + 999) / 1000;
 776     interval = (interval + 999) / 1000;
 777
 778     timer->interval = interval;
 779     if (DosAsyncTimer (value, (HSEM)timer->hev, &timer->htimer))
 780         abort ();
 781 }
 782
 783 unsigned vlc_timer_getoverrun (vlc_timer_t timer)
 784 {
 785     (void)timer;
 786     return 0;
 787 }
 788
 789 /*** CPU ***/
 790 unsigned vlc_GetCPUCount (void)
 791 {
 792     ULONG numprocs = 1;
 793
 794     DosQuerySysInfo(QSV_NUMPROCESSORS, QSV_NUMPROCESSORS,
 795                     &numprocs, sizeof(numprocs));
 796
 797     return numprocs;
 798 }