loader/task.c

   1 /*
   2  * Task functions
   3  *
   4  * Copyright 1995 Alexandre Julliard
   5  */
   6
   7 #include <stdlib.h>
   8 #include <string.h>
   9 #include <assert.h>
  10 #include <unistd.h>
  11
  12 #include "wine/winbase16.h"
  13 #include "callback.h"
  14 #include "drive.h"
  15 #include "file.h"
  16 #include "global.h"
  17 #include "instance.h"
  18 #include "message.h"
  19 #include "miscemu.h"
  20 #include "module.h"
  21 #include "neexe.h"
  22 #include "pe_image.h"
  23 #include "process.h"
  24 #include "queue.h"
  25 #include "selectors.h"
  26 #include "stackframe.h"
  27 #include "task.h"
  28 #include "thread.h"
  29 #include "toolhelp.h"
  30 #include "winnt.h"
  31 #include "winsock.h"
  32 #include "syslevel.h"
  33 #include "debugtools.h"
  34 #include "dosexe.h"
  35 #include "services.h"
  36 #include "server.h"
  37
  38 DEFAULT_DEBUG_CHANNEL(task)
  39 DECLARE_DEBUG_CHANNEL(relay)
  40 DECLARE_DEBUG_CHANNEL(toolhelp)
  41
  42   /* Min. number of thunks allocated when creating a new segment */
  43 #define MIN_THUNKS  32
  44
  45
  46 static THHOOK DefaultThhook = { 0 };
  47 THHOOK *pThhook = &DefaultThhook;
  48
  49 #define hCurrentTask (pThhook->CurTDB)
  50 #define hFirstTask   (pThhook->HeadTDB)
  51 #define hLockedTask  (pThhook->LockTDB)
  52
  53 static UINT16 nTaskCount = 0;
  54
  55 static HTASK initial_task;
  56
  57 /***********************************************************************
  58  *           TASK_InstallTHHook
  59  */
  60 void TASK_InstallTHHook( THHOOK *pNewThhook )
  61 {
  62      THHOOK *pOldThhook = pThhook;
  63
  64      pThhook = pNewThhook? pNewThhook : &DefaultThhook;
  65
  66      *pThhook = *pOldThhook;
  67 }
  68
  69 /***********************************************************************
  70  *           TASK_GetNextTask
  71  */
  72 HTASK16 TASK_GetNextTask( HTASK16 hTask )
  73 {
  74     TDB* pTask = (TDB*)GlobalLock16(hTask);
  75
  76     if (pTask->hNext) return pTask->hNext;
  77     return (hFirstTask != hTask) ? hFirstTask : 0;
  78 }
  79
  80 /***********************************************************************
  81  *           TASK_LinkTask
  82  */
  83 static void TASK_LinkTask( HTASK16 hTask )
  84 {
  85     HTASK16 *prevTask;
  86     TDB *pTask;
  87
  88     if (!(pTask = (TDB *)GlobalLock16( hTask ))) return;
  89     prevTask = &hFirstTask;
  90     while (*prevTask)
  91     {
  92         TDB *prevTaskPtr = (TDB *)GlobalLock16( *prevTask );
  93         if (prevTaskPtr->priority >= pTask->priority) break;
  94         prevTask = &prevTaskPtr->hNext;
  95     }
  96     pTask->hNext = *prevTask;
  97     *prevTask = hTask;
  98     nTaskCount++;
  99 }
 100
 101
 102 /***********************************************************************
 103  *           TASK_UnlinkTask
 104  */
 105 static void TASK_UnlinkTask( HTASK16 hTask )
 106 {
 107     HTASK16 *prevTask;
 108     TDB *pTask;
 109
 110     prevTask = &hFirstTask;
 111     while (*prevTask && (*prevTask != hTask))
 112     {
 113         pTask = (TDB *)GlobalLock16( *prevTask );
 114         prevTask = &pTask->hNext;
 115     }
 116     if (*prevTask)
 117     {
 118         pTask = (TDB *)GlobalLock16( *prevTask );
 119         *prevTask = pTask->hNext;
 120         pTask->hNext = 0;
 121         nTaskCount--;
 122     }
 123 }
 124
 125
 126 /***********************************************************************
 127  *           TASK_CreateThunks
 128  *
 129  * Create a thunk free-list in segment 'handle', starting from offset 'offset'
 130  * and containing 'count' entries.
 131  */
 132 static void TASK_CreateThunks( HGLOBAL16 handle, WORD offset, WORD count )
 133 {
 134     int i;
 135     WORD free;
 136     THUNKS *pThunk;
 137
 138     pThunk = (THUNKS *)((BYTE *)GlobalLock16( handle ) + offset);
 139     pThunk->next = 0;
 140     pThunk->magic = THUNK_MAGIC;
 141     pThunk->free = (int)&pThunk->thunks - (int)pThunk;
 142     free = pThunk->free;
 143     for (i = 0; i < count-1; i++)
 144     {
 145         free += 8;  /* Offset of next thunk */
 146         pThunk->thunks[4*i] = free;
 147     }
 148     pThunk->thunks[4*i] = 0;  /* Last thunk */
 149 }
 150
 151
 152 /***********************************************************************
 153  *           TASK_AllocThunk
 154  *
 155  * Allocate a thunk for MakeProcInstance().
 156  */
 157 static SEGPTR TASK_AllocThunk( HTASK16 hTask )
 158 {
 159     TDB *pTask;
 160     THUNKS *pThunk;
 161     WORD sel, base;
 162
 163     if (!(pTask = (TDB *)GlobalLock16( hTask ))) return 0;
 164     sel = pTask->hCSAlias;
 165     pThunk = &pTask->thunks;
 166     base = (int)pThunk - (int)pTask;
 167     while (!pThunk->free)
 168     {
 169         sel = pThunk->next;
 170         if (!sel)  /* Allocate a new segment */
 171         {
 172             sel = GLOBAL_Alloc( GMEM_FIXED, sizeof(THUNKS) + (MIN_THUNKS-1)*8,
 173                                 pTask->hPDB, TRUE, FALSE, FALSE );
 174             if (!sel) return (SEGPTR)0;
 175             TASK_CreateThunks( sel, 0, MIN_THUNKS );
 176             pThunk->next = sel;
 177         }
 178         pThunk = (THUNKS *)GlobalLock16( sel );
 179         base = 0;
 180     }
 181     base += pThunk->free;
 182     pThunk->free = *(WORD *)((BYTE *)pThunk + pThunk->free);
 183     return PTR_SEG_OFF_TO_SEGPTR( sel, base );
 184 }
 185
 186
 187 /***********************************************************************
 188  *           TASK_FreeThunk
 189  *
 190  * Free a MakeProcInstance() thunk.
 191  */
 192 static BOOL TASK_FreeThunk( HTASK16 hTask, SEGPTR thunk )
 193 {
 194     TDB *pTask;
 195     THUNKS *pThunk;
 196     WORD sel, base;
 197
 198     if (!(pTask = (TDB *)GlobalLock16( hTask ))) return 0;
 199     sel = pTask->hCSAlias;
 200     pThunk = &pTask->thunks;
 201     base = (int)pThunk - (int)pTask;
 202     while (sel && (sel != HIWORD(thunk)))
 203     {
 204         sel = pThunk->next;
 205         pThunk = (THUNKS *)GlobalLock16( sel );
 206         base = 0;
 207     }
 208     if (!sel) return FALSE;
 209     *(WORD *)((BYTE *)pThunk + LOWORD(thunk) - base) = pThunk->free;
 210     pThunk->free = LOWORD(thunk) - base;
 211     return TRUE;
 212 }
 213
 214
 215 /***********************************************************************
 216  *           TASK_CallToStart
 217  *
 218  * 32-bit entry point for a new task. This function is responsible for
 219  * setting up the registers and jumping to the 16-bit entry point.
 220  */
 221 void TASK_CallToStart(void)
 222 {
 223     TDB *pTask = (TDB *)GlobalLock16( GetCurrentTask() );
 224     NE_MODULE *pModule = NE_GetPtr( pTask->hModule );
 225     SEGTABLEENTRY *pSegTable = NE_SEG_TABLE( pModule );
 226     CONTEXT86 context;
 227
 228     SYSLEVEL_EnterWin16Lock();
 229
 230     /* Add task to 16-bit scheduler pool if necessary */
 231     if ( hCurrentTask != GetCurrentTask() )
 232         TASK_Reschedule();
 233
 234     /* Registers at initialization must be:
 235      * ax   zero
 236      * bx   stack size in bytes
 237      * cx   heap size in bytes
 238      * si   previous app instance
 239      * di   current app instance
 240      * bp   zero
 241      * es   selector to the PSP
 242      * ds   dgroup of the application
 243      * ss   stack selector
 244      * sp   top of the stack
 245      */
 246
 247     memset( &context, 0, sizeof(context) );
 248     CS_reg(&context)  = GlobalHandleToSel16(pSegTable[pModule->cs - 1].hSeg);
 249     DS_reg(&context)  = GlobalHandleToSel16(pTask->hInstance);
 250     ES_reg(&context)  = pTask->hPDB;
 251     EIP_reg(&context) = pModule->ip;
 252     EBX_reg(&context) = pModule->stack_size;
 253     ECX_reg(&context) = pModule->heap_size;
 254     EDI_reg(&context) = pTask->hInstance;
 255     ESI_reg(&context) = pTask->hPrevInstance;
 256
 257     TRACE("Starting main program: cs:ip=%04lx:%04lx ds=%04lx ss:sp=%04x:%04x\n",
 258           CS_reg(&context), EIP_reg(&context), DS_reg(&context),
 259           SELECTOROF(pTask->teb->cur_stack),
 260           OFFSETOF(pTask->teb->cur_stack) );
 261
 262     Callbacks->CallRegisterShortProc( &context, 0 );
 263 }
 264
 265
 266 /***********************************************************************
 267  *           TASK_Create
 268  *
 269  * NOTE: This routine might be called by a Win32 thread. Thus, we need
 270  *       to be careful to protect global data structures. We do this
 271  *       by entering the Win16Lock while linking the task into the
 272  *       global task list.
 273  */
 274 BOOL TASK_Create( NE_MODULE *pModule, UINT16 cmdShow, TEB *teb, LPCSTR cmdline, BYTE len )
 275 {
 276     HTASK16 hTask;
 277     TDB *pTask;
 278     char name[10];
 279     PDB *pdb32 = PROCESS_Current();
 280
 281       /* Allocate the task structure */
 282
 283     hTask = GLOBAL_Alloc( GMEM_FIXED | GMEM_ZEROINIT, sizeof(TDB),
 284                           pModule->self, FALSE, FALSE, FALSE );
 285     if (!hTask) return FALSE;
 286     pTask = (TDB *)GlobalLock16( hTask );
 287
 288     /* Fill the task structure */
 289
 290     pTask->nEvents       = 0;
 291     pTask->hSelf         = hTask;
 292     pTask->flags         = 0;
 293
 294     if (teb->tibflags & TEBF_WIN32) pTask->flags |= TDBF_WIN32;
 295     if (pModule->lpDosTask) pTask->flags |= TDBF_WINOLDAP;
 296
 297     pTask->hInstance     = pModule->self;
 298     pTask->hPrevInstance = 0;
 299     /* NOTE: for 16-bit tasks, the instance handles are updated later on
 300              in NE_InitProcess */
 301
 302     pTask->version       = pModule->expected_version;
 303     pTask->hModule       = pModule->self;
 304     pTask->hParent       = GetCurrentTask();
 305     pTask->magic         = TDB_MAGIC;
 306     pTask->nCmdShow      = cmdShow;
 307     pTask->teb           = teb;
 308     pTask->curdrive      = DRIVE_GetCurrentDrive() | 0x80;
 309     strcpy( pTask->curdir, "\\" );
 310     lstrcpynA( pTask->curdir + 1, DRIVE_GetDosCwd( DRIVE_GetCurrentDrive() ),
 311                  sizeof(pTask->curdir) - 1 );
 312
 313       /* Create the thunks block */
 314
 315     TASK_CreateThunks( hTask, (int)&pTask->thunks - (int)pTask, 7 );
 316
 317       /* Copy the module name */
 318
 319     GetModuleName16( pModule->self, name, sizeof(name) );
 320     strncpy( pTask->module_name, name, sizeof(pTask->module_name) );
 321
 322       /* Allocate a selector for the PDB */
 323
 324     pTask->hPDB = GLOBAL_CreateBlock( GMEM_FIXED, &pTask->pdb, sizeof(PDB16),
 325                                     pModule->self, FALSE, FALSE, FALSE, NULL );
 326
 327       /* Fill the PDB */
 328
 329     pTask->pdb.int20 = 0x20cd;
 330     pTask->pdb.dispatcher[0] = 0x9a;  /* ljmp */
 331     PUT_DWORD(&pTask->pdb.dispatcher[1], (DWORD)NE_GetEntryPoint(
 332            GetModuleHandle16("KERNEL"), 102 ));  /* KERNEL.102 is DOS3Call() */
 333     pTask->pdb.savedint22 = INT_GetPMHandler( 0x22 );
 334     pTask->pdb.savedint23 = INT_GetPMHandler( 0x23 );
 335     pTask->pdb.savedint24 = INT_GetPMHandler( 0x24 );
 336     pTask->pdb.fileHandlesPtr =
 337         PTR_SEG_OFF_TO_SEGPTR( GlobalHandleToSel16(pTask->hPDB),
 338                                (int)&((PDB16 *)0)->fileHandles );
 339     pTask->pdb.hFileHandles = 0;
 340     memset( pTask->pdb.fileHandles, 0xff, sizeof(pTask->pdb.fileHandles) );
 341     pTask->pdb.environment    = pdb32->env_db->env_sel;
 342     pTask->pdb.nbFiles        = 20;
 343
 344     /* Fill the command line */
 345
 346     if (!cmdline)
 347     {
 348         cmdline = pdb32->env_db->cmd_line;
 349         while (*cmdline && (*cmdline != ' ') && (*cmdline != '\t')) cmdline++;
 350         while ((*cmdline == ' ') || (*cmdline == '\t')) cmdline++;
 351         len = strlen(cmdline);
 352     }
 353     if (len >= sizeof(pTask->pdb.cmdLine)) len = sizeof(pTask->pdb.cmdLine)-1;
 354     pTask->pdb.cmdLine[0] = len;
 355     memcpy( pTask->pdb.cmdLine + 1, cmdline, len );
 356     /* pTask->pdb.cmdLine[len+1] = 0; */
 357
 358       /* Get the compatibility flags */
 359
 360     pTask->compat_flags = GetProfileIntA( "Compatibility", name, 0 );
 361
 362       /* Allocate a code segment alias for the TDB */
 363
 364     pTask->hCSAlias = GLOBAL_CreateBlock( GMEM_FIXED, (void *)pTask,
 365                                           sizeof(TDB), pTask->hPDB, TRUE,
 366                                           FALSE, FALSE, NULL );
 367
 368       /* Set the owner of the environment block */
 369
 370     FarSetOwner16( pTask->pdb.environment, pTask->hPDB );
 371
 372       /* Default DTA overwrites command-line */
 373
 374     pTask->dta = PTR_SEG_OFF_TO_SEGPTR( pTask->hPDB,
 375                                 (int)&pTask->pdb.cmdLine - (int)&pTask->pdb );
 376
 377     /* Create scheduler event for 16-bit tasks */
 378
 379     if ( !(pTask->flags & TDBF_WIN32) )
 380     {
 381         pTask->hEvent = CreateEventA( NULL, TRUE, FALSE, NULL );
 382         pTask->hEvent = ConvertToGlobalHandle( pTask->hEvent );
 383     }
 384
 385     /* Enter task handle into thread and process */
 386
 387     teb->htask16 = hTask;
 388     if (!initial_task) initial_task = hTask;
 389
 390     TRACE("module='%s' cmdline='%.*s' task=%04x\n", name, *cmdline, cmdline+1, hTask );
 391
 392     /* Add the task to the linked list */
 393
 394     SYSLEVEL_EnterWin16Lock();
 395     TASK_LinkTask( hTask );
 396     SYSLEVEL_LeaveWin16Lock();
 397
 398     return TRUE;
 399 }
 400
 401 /***********************************************************************
 402  *           TASK_DeleteTask
 403  */
 404 static void TASK_DeleteTask( HTASK16 hTask )
 405 {
 406     TDB *pTask;
 407     HGLOBAL16 hPDB;
 408
 409     if (!(pTask = (TDB *)GlobalLock16( hTask ))) return;
 410     hPDB = pTask->hPDB;
 411
 412     pTask->magic = 0xdead; /* invalidate signature */
 413
 414     /* Free the selector aliases */
 415
 416     GLOBAL_FreeBlock( pTask->hCSAlias );
 417     GLOBAL_FreeBlock( pTask->hPDB );
 418
 419     /* Free the task module */
 420
 421     FreeModule16( pTask->hModule );
 422
 423     /* Free the task structure itself */
 424
 425     GlobalFree16( hTask );
 426
 427     /* Free all memory used by this task (including the 32-bit stack, */
 428     /* the environment block and the thunk segments). */
 429
 430     GlobalFreeAll16( hPDB );
 431 }
 432
 433 /***********************************************************************
 434  *           TASK_KillTask
 435  */
 436 void TASK_KillTask( HTASK16 hTask )
 437 {
 438     TDB *pTask;
 439
 440     /* Enter the Win16Lock to protect global data structures */
 441     SYSLEVEL_EnterWin16Lock();
 442
 443     if ( !hTask ) hTask = GetCurrentTask();
 444     pTask = (TDB *)GlobalLock16( hTask );
 445     if ( !pTask )
 446     {
 447         SYSLEVEL_LeaveWin16Lock();
 448         return;
 449     }
 450
 451     TRACE("Killing task %04x\n", hTask );
 452
 453 #ifdef MZ_SUPPORTED
 454 {
 455     /* Kill DOS VM task */
 456     NE_MODULE *pModule = NE_GetPtr( pTask->hModule );
 457     if ( pModule->lpDosTask )
 458         MZ_KillModule( pModule->lpDosTask );
 459 }
 460 #endif
 461
 462     /* Perform USER cleanup */
 463
 464     TASK_CallTaskSignalProc( USIG16_TERMINATION, hTask );
 465     PROCESS_CallUserSignalProc( USIG_PROCESS_EXIT, 0 );
 466     PROCESS_CallUserSignalProc( USIG_THREAD_EXIT, 0 );
 467     PROCESS_CallUserSignalProc( USIG_PROCESS_DESTROY, 0 );
 468
 469     if (nTaskCount <= 1)
 470     {
 471         TRACE("this is the last task, exiting\n" );
 472         ExitKernel16();
 473     }
 474
 475     /* FIXME: Hack! Send a message to the initial task so that
 476      * the GetMessage wakes up and the initial task can check whether
 477      * it is the only remaining one and terminate itself ...
 478      * The initial task should probably install hooks or something
 479      * to get informed about task termination :-/
 480      */
 481     Callout.PostAppMessage16( initial_task, WM_NULL, 0, 0 );
 482
 483     /* Remove the task from the list to be sure we never switch back to it */
 484     TASK_UnlinkTask( hTask );
 485     if( nTaskCount )
 486     {
 487         TDB* p = (TDB *)GlobalLock16( hFirstTask );
 488         while( p )
 489         {
 490             if( p->hYieldTo == hTask ) p->hYieldTo = 0;
 491             p = (TDB *)GlobalLock16( p->hNext );
 492         }
 493     }
 494
 495     pTask->nEvents = 0;
 496
 497     if ( hLockedTask == hTask )
 498         hLockedTask = 0;
 499
 500     TASK_DeleteTask( hTask );
 501
 502     /* When deleting the current task ... */
 503     if ( hTask == hCurrentTask )
 504     {
 505         DWORD lockCount;
 506
 507         /* ... schedule another one ... */
 508         TASK_Reschedule();
 509
 510         /* ... and completely release the Win16Lock, just in case. */
 511         ReleaseThunkLock( &lockCount );
 512
 513         return;
 514     }
 515
 516     SYSLEVEL_LeaveWin16Lock();
 517 }
 518
 519 /***********************************************************************
 520  *           TASK_Reschedule
 521  *
 522  * This is where all the magic of task-switching happens!
 523  *
 524  * 16-bit Windows performs non-preemptive (cooperative) multitasking.
 525  * This means that each 16-bit task runs until it voluntarily yields
 526  * control, at which point the scheduler gets active and selects the
 527  * next task to run.
 528  *
 529  * In Wine, all processes, even 16-bit ones, are scheduled preemptively
 530  * by the standard scheduler of the underlying OS.  As many 16-bit apps
 531  * *rely* on the behaviour of the Windows scheduler, however, we have
 532  * to simulate that behaviour.
 533  *
 534  * This is achieved as follows: every 16-bit task is at time (except
 535  * during task creation and deletion) in one of two states: either it
 536  * is the one currently running, then the global variable hCurrentTask
 537  * contains its task handle, or it is not currently running, then it
 538  * is blocked on a special scheduler event, a global handle to which
 539  * is stored in the task struct.
 540  *
 541  * When the current task yields control, this routine gets called. Its
 542  * purpose is to determine the next task to be active, signal the
 543  * scheduler event of that task, and then put the current task to sleep
 544  * waiting for *its* scheduler event to get signalled again.
 545  *
 546  * This routine can get called in a few other special situations as well:
 547  *
 548  * - On creation of a 16-bit task, the Unix process executing the task
 549  *   calls TASK_Reschedule once it has completed its initialization.
 550  *   At this point, the task needs to be blocked until its scheduler
 551  *   event is signalled the first time (this will be done by the parent
 552  *   process to get the task up and running).
 553  *
 554  * - When the task currently running terminates itself, this routine gets
 555  *   called and has to schedule another task, *without* blocking the
 556  *   terminating task.
 557  *
 558  * - When a 32-bit thread posts an event for a 16-bit task, it might be
 559  *   the case that *no* 16-bit task is currently running.  In this case
 560  *   the task that has now an event pending is to be scheduled.
 561  *
 562  */
 563 void TASK_Reschedule(void)
 564 {
 565     TDB *pOldTask = NULL, *pNewTask = NULL;
 566     HTASK16 hOldTask = 0, hNewTask = 0;
 567     enum { MODE_YIELD, MODE_SLEEP, MODE_WAKEUP } mode;
 568     DWORD lockCount;
 569
 570     SYSLEVEL_EnterWin16Lock();
 571
 572     /* Check what we need to do */
 573     hOldTask = GetCurrentTask();
 574     pOldTask = (TDB *)GlobalLock16( hOldTask );
 575     TRACE( "entered with hCurrentTask %04x by hTask %04x (pid %ld)\n",
 576            hCurrentTask, hOldTask, (long) getpid() );
 577
 578     if ( pOldTask && THREAD_IsWin16( NtCurrentTeb() ) )
 579     {
 580         /* We are called by an active (non-deleted) 16-bit task */
 581
 582         /* If we don't even have a current task, or else the current
 583            task has yielded, we'll need to schedule a new task and
 584            (possibly) put the calling task to sleep.  Otherwise, we
 585            only block the caller. */
 586
 587         if ( !hCurrentTask || hCurrentTask == hOldTask )
 588             mode = MODE_YIELD;
 589         else
 590             mode = MODE_SLEEP;
 591     }
 592     else
 593     {
 594         /* We are called by a deleted 16-bit task or a 32-bit thread */
 595
 596         /* The only situation where we need to do something is if we
 597            now do not have a current task.  Then, we'll need to wake up
 598            some task that has events pending. */
 599
 600         if ( !hCurrentTask || hCurrentTask == hOldTask )
 601             mode = MODE_WAKEUP;
 602         else
 603         {
 604             /* nothing to do */
 605             SYSLEVEL_LeaveWin16Lock();
 606             return;
 607         }
 608     }
 609
 610     /* Find a task to yield to: check for DirectedYield() */
 611     if ( mode == MODE_YIELD && pOldTask && pOldTask->hYieldTo )
 612     {
 613         hNewTask = pOldTask->hYieldTo;
 614         pNewTask = (TDB *)GlobalLock16( hNewTask );
 615         if( !pNewTask || !pNewTask->nEvents) hNewTask = 0;
 616         pOldTask->hYieldTo = 0;
 617     }
 618
 619     /* Find a task to yield to: check for pending events */
 620     if ( (mode == MODE_YIELD || mode == MODE_WAKEUP) && !hNewTask )
 621     {
 622         hNewTask = hFirstTask;
 623         while (hNewTask)
 624         {
 625             pNewTask = (TDB *)GlobalLock16( hNewTask );
 626
 627             TRACE( "\ttask = %04x, events = %i\n", hNewTask, pNewTask->nEvents );
 628
 629             if (pNewTask->nEvents) break;
 630             hNewTask = pNewTask->hNext;
 631         }
 632         if (hLockedTask && (hNewTask != hLockedTask)) hNewTask = 0;
 633     }
 634
 635     /* If we are still the task with highest priority, just return ... */
 636     if ( mode == MODE_YIELD && hNewTask && hNewTask == hCurrentTask )
 637     {
 638         TRACE("returning to the current task (%04x)\n", hCurrentTask );
 639         SYSLEVEL_LeaveWin16Lock();
 640
 641         /* Allow Win32 threads to thunk down even while a Win16 task is
 642            in a tight PeekMessage() or Yield() loop ... */
 643         ReleaseThunkLock( &lockCount );
 644         RestoreThunkLock( lockCount );
 645         return;
 646     }
 647
 648     /* If no task to yield to found, suspend 16-bit scheduler ... */
 649     if ( mode == MODE_YIELD && !hNewTask )
 650     {
 651         TRACE("No currently active task\n");
 652         hCurrentTask = 0;
 653     }
 654
 655     /* If we found a task to wake up, do it ... */
 656     if ( (mode == MODE_YIELD || mode == MODE_WAKEUP) && hNewTask )
 657     {
 658         TRACE("Switching to task %04x (%.8s)\n",
 659                       hNewTask, pNewTask->module_name );
 660
 661         pNewTask->priority++;
 662         TASK_UnlinkTask( hNewTask );
 663         TASK_LinkTask( hNewTask );
 664         pNewTask->priority--;
 665
 666         hCurrentTask = hNewTask;
 667         SetEvent( pNewTask->hEvent );
 668
 669         /* This is set just in case some app reads it ... */
 670         pNewTask->ss_sp = pNewTask->teb->cur_stack;
 671     }
 672
 673     /* If we need to put the current task to sleep, do it ... */
 674     if ( (mode == MODE_YIELD || mode == MODE_SLEEP) && hOldTask != hCurrentTask )
 675     {
 676         ResetEvent( pOldTask->hEvent );
 677
 678         ReleaseThunkLock( &lockCount );
 679         SYSLEVEL_CheckNotLevel( 1 );
 680         WaitForSingleObject( pOldTask->hEvent, INFINITE );
 681         RestoreThunkLock( lockCount );
 682     }
 683
 684     SYSLEVEL_LeaveWin16Lock();
 685 }
 686
 687 /***********************************************************************
 688  *           InitTask  (KERNEL.91)
 689  *
 690  * Called by the application startup code.
 691  */
 692 void WINAPI InitTask16( CONTEXT86 *context )
 693 {
 694     TDB *pTask;
 695     INSTANCEDATA *pinstance;
 696     SEGPTR ptr;
 697
 698     EAX_reg(context) = 0;
 699     if (!(pTask = (TDB *)GlobalLock16( GetCurrentTask() ))) return;
 700
 701     /* Note: we need to trust that BX/CX contain the stack/heap sizes,
 702        as some apps, notably Visual Basic apps, *modify* the heap/stack
 703        size of the instance data segment before calling InitTask() */
 704
 705     /* Initialize the INSTANCEDATA structure */
 706     pinstance = (INSTANCEDATA *)PTR_SEG_OFF_TO_LIN(CURRENT_DS, 0);
 707     pinstance->stackmin    = OFFSETOF( pTask->teb->cur_stack ) + sizeof( STACK16FRAME );
 708     pinstance->stackbottom = pinstance->stackmin; /* yup, that's right. Confused me too. */
 709     pinstance->stacktop    = ( pinstance->stackmin > BX_reg(context)?
 710                                pinstance->stackmin - BX_reg(context) : 0 ) + 150;
 711
 712     /* Initialize the local heap */
 713     if ( CX_reg(context) )
 714         LocalInit16( GlobalHandleToSel16(pTask->hInstance), 0, CX_reg(context) );
 715
 716     /* Initialize implicitly loaded DLLs */
 717     NE_InitializeDLLs( pTask->hModule );
 718     NE_DllProcessAttach( pTask->hModule );
 719
 720     /* Registers on return are:
 721      * ax     1 if OK, 0 on error
 722      * cx     stack limit in bytes
 723      * dx     cmdShow parameter
 724      * si     instance handle of the previous instance
 725      * di     instance handle of the new task
 726      * es:bx  pointer to command-line inside PSP
 727      *
 728      * 0 (=%bp) is pushed on the stack
 729      */
 730     ptr = stack16_push( sizeof(WORD) );
 731     *(WORD *)PTR_SEG_TO_LIN(ptr) = 0;
 732     ESP_reg(context) -= 2;
 733
 734     EAX_reg(context) = 1;
 735
 736     if (!pTask->pdb.cmdLine[0]) EBX_reg(context) = 0x80;
 737     else
 738     {
 739         LPBYTE p = &pTask->pdb.cmdLine[1];
 740         while ((*p == ' ') || (*p == '\t')) p++;
 741         EBX_reg(context) = 0x80 + (p - pTask->pdb.cmdLine);
 742     }
 743     ECX_reg(context) = pinstance->stacktop;
 744     EDX_reg(context) = pTask->nCmdShow;
 745     ESI_reg(context) = (DWORD)pTask->hPrevInstance;
 746     EDI_reg(context) = (DWORD)pTask->hInstance;
 747     ES_reg (context) = (WORD)pTask->hPDB;
 748 }
 749
 750
 751 /***********************************************************************
 752  *           WaitEvent  (KERNEL.30)
 753  */
 754 BOOL16 WINAPI WaitEvent16( HTASK16 hTask )
 755 {
 756     TDB *pTask;
 757
 758     if (!hTask) hTask = GetCurrentTask();
 759     pTask = (TDB *)GlobalLock16( hTask );
 760
 761     if ( !THREAD_IsWin16( NtCurrentTeb() ) )
 762     {
 763         FIXME("called for Win32 thread (%04x)!\n", NtCurrentTeb()->teb_sel);
 764         return TRUE;
 765     }
 766
 767     if (pTask->nEvents > 0)
 768     {
 769         pTask->nEvents--;
 770         return FALSE;
 771     }
 772     TASK_Reschedule();
 773
 774     /* When we get back here, we have an event */
 775
 776     if (pTask->nEvents > 0) pTask->nEvents--;
 777     return TRUE;
 778 }
 779
 780
 781 /***********************************************************************
 782  *           PostEvent  (KERNEL.31)
 783  */
 784 void WINAPI PostEvent16( HTASK16 hTask )
 785 {
 786     TDB *pTask;
 787
 788     if (!hTask) hTask = GetCurrentTask();
 789     if (!(pTask = (TDB *)GlobalLock16( hTask ))) return;
 790
 791     if ( !THREAD_IsWin16( pTask->teb ) )
 792     {
 793         FIXME("called for Win32 thread (%04x)!\n", pTask->teb->teb_sel );
 794         return;
 795     }
 796
 797     pTask->nEvents++;
 798
 799     /* If we are a 32-bit task, we might need to wake up the 16-bit scheduler */
 800     if ( !THREAD_IsWin16( NtCurrentTeb() ) )
 801         TASK_Reschedule();
 802 }
 803
 804
 805 /***********************************************************************
 806  *           SetPriority  (KERNEL.32)
 807  */
 808 void WINAPI SetPriority16( HTASK16 hTask, INT16 delta )
 809 {
 810     TDB *pTask;
 811     INT16 newpriority;
 812
 813     if (!hTask) hTask = GetCurrentTask();
 814     if (!(pTask = (TDB *)GlobalLock16( hTask ))) return;
 815     newpriority = pTask->priority + delta;
 816     if (newpriority < -32) newpriority = -32;
 817     else if (newpriority > 15) newpriority = 15;
 818
 819     pTask->priority = newpriority + 1;
 820     TASK_UnlinkTask( hTask );
 821     TASK_LinkTask( hTask );
 822     pTask->priority--;
 823 }
 824
 825
 826 /***********************************************************************
 827  *           LockCurrentTask  (KERNEL.33)
 828  */
 829 HTASK16 WINAPI LockCurrentTask16( BOOL16 bLock )
 830 {
 831     if (bLock) hLockedTask = GetCurrentTask();
 832     else hLockedTask = 0;
 833     return hLockedTask;
 834 }
 835
 836
 837 /***********************************************************************
 838  *           IsTaskLocked  (KERNEL.122)
 839  */
 840 HTASK16 WINAPI IsTaskLocked16(void)
 841 {
 842     return hLockedTask;
 843 }
 844
 845
 846 /***********************************************************************
 847  *           OldYield  (KERNEL.117)
 848  */
 849 void WINAPI OldYield16(void)
 850 {
 851     TDB *pCurTask = (TDB *)GlobalLock16( GetCurrentTask() );
 852
 853     if ( !THREAD_IsWin16( NtCurrentTeb() ) )
 854     {
 855         FIXME("called for Win32 thread (%04x)!\n", NtCurrentTeb()->teb_sel);
 856         return;
 857     }
 858
 859     if (pCurTask) pCurTask->nEvents++;  /* Make sure we get back here */
 860     TASK_Reschedule();
 861     if (pCurTask) pCurTask->nEvents--;
 862 }
 863
 864 /***********************************************************************
 865  *           WIN32_OldYield16  (KERNEL.447)
 866  */
 867 void WINAPI WIN32_OldYield16(void)
 868 {
 869    DWORD count;
 870
 871    ReleaseThunkLock(&count);
 872    RestoreThunkLock(count);
 873 }
 874
 875 /***********************************************************************
 876  *           DirectedYield  (KERNEL.150)
 877  */
 878 void WINAPI DirectedYield16( HTASK16 hTask )
 879 {
 880     TDB *pCurTask = (TDB *)GlobalLock16( GetCurrentTask() );
 881
 882     if ( !THREAD_IsWin16( NtCurrentTeb() ) )
 883     {
 884         FIXME("called for Win32 thread (%04x)!\n", NtCurrentTeb()->teb_sel);
 885         return;
 886     }
 887
 888     TRACE("%04x: DirectedYield(%04x)\n", pCurTask->hSelf, hTask );
 889
 890     pCurTask->hYieldTo = hTask;
 891     OldYield16();
 892
 893     TRACE("%04x: back from DirectedYield(%04x)\n", pCurTask->hSelf, hTask );
 894 }
 895
 896 /***********************************************************************
 897  *           Yield16  (KERNEL.29)
 898  */
 899 void WINAPI Yield16(void)
 900 {
 901     TDB *pCurTask = (TDB *)GlobalLock16( GetCurrentTask() );
 902
 903     if (pCurTask) pCurTask->hYieldTo = 0;
 904     if (pCurTask && pCurTask->hQueue) Callout.UserYield16();
 905     else OldYield16();
 906 }
 907
 908 /***********************************************************************
 909  *           KERNEL_490  (KERNEL.490)
 910  */
 911 HTASK16 WINAPI KERNEL_490( HTASK16 someTask )
 912 {
 913     if ( !someTask ) return 0;
 914
 915     FIXME("(%04x): stub\n", someTask );
 916     return 0;
 917 }
 918
 919 /***********************************************************************
 920  *           MakeProcInstance16  (KERNEL.51)
 921  */
 922 FARPROC16 WINAPI MakeProcInstance16( FARPROC16 func, HANDLE16 hInstance )
 923 {
 924     BYTE *thunk,*lfunc;
 925     SEGPTR thunkaddr;
 926     WORD hInstanceSelector;
 927
 928     hInstanceSelector = GlobalHandleToSel16(hInstance);
 929
 930     TRACE("(%08lx, %04x);\n", (DWORD)func, hInstance);
 931
 932     if (!HIWORD(func)) {
 933       /* Win95 actually protects via SEH, but this is better for debugging */
 934       ERR("Ouch ! Called with invalid func 0x%08lx !\n", (DWORD)func);
 935       return (FARPROC16)0;
 936     }
 937
 938     if (hInstance)
 939     {
 940         if ( (!(hInstance & 4)) ||
 941              ((hInstance != 0xffff) && IS_SELECTOR_FREE(hInstance|7)) )
 942         {
 943             ERR("Invalid hInstance (%04x) passed to MakeProcInstance !\n",
 944                 hInstance);
 945             return 0;
 946         }
 947     }
 948
 949     if ( (CURRENT_DS != hInstanceSelector)
 950       && (hInstance != 0)
 951       && (hInstance != 0xffff) )
 952     {
 953         /* calling MPI with a foreign DSEG is invalid ! */
 954         ERR("Problem with hInstance? Got %04x, using %04x instead\n",
 955                    hInstance,CURRENT_DS);
 956     }
 957
 958     /* Always use the DSEG that MPI was entered with.
 959      * We used to set hInstance to GetTaskDS16(), but this should be wrong
 960      * as CURRENT_DS provides the DSEG value we need.
 961      * ("calling" DS, *not* "task" DS !) */
 962     hInstanceSelector = CURRENT_DS;
 963     hInstance = GlobalHandle16(hInstanceSelector);
 964
 965     /* no thunking for DLLs */
 966     if (NE_GetPtr(FarGetOwner16(hInstance))->flags & NE_FFLAGS_LIBMODULE)
 967         return func;
 968
 969     thunkaddr = TASK_AllocThunk( GetCurrentTask() );
 970     if (!thunkaddr) return (FARPROC16)0;
 971     thunk = PTR_SEG_TO_LIN( thunkaddr );
 972     lfunc = PTR_SEG_TO_LIN( func );
 973
 974     TRACE("(%08lx,%04x): got thunk %08lx\n",
 975           (DWORD)func, hInstance, (DWORD)thunkaddr );
 976     if (((lfunc[0]==0x8c) && (lfunc[1]==0xd8)) || /* movw %ds, %ax */
 977         ((lfunc[0]==0x1e) && (lfunc[1]==0x58))    /* pushw %ds, popw %ax */
 978     ) {
 979         FIXME("This was the (in)famous \"thunk useless\" warning. We thought we have to overwrite with nop;nop;, but this isn't true.\n");
 980     }
 981
 982     *thunk++ = 0xb8;    /* movw instance, %ax */
 983     *thunk++ = (BYTE)(hInstanceSelector & 0xff);
 984     *thunk++ = (BYTE)(hInstanceSelector >> 8);
 985     *thunk++ = 0xea;    /* ljmp func */
 986     *(DWORD *)thunk = (DWORD)func;
 987     return (FARPROC16)thunkaddr;
 988     /* CX reg indicates if thunkaddr != NULL, implement if needed */
 989 }
 990
 991
 992 /***********************************************************************
 993  *           FreeProcInstance16  (KERNEL.52)
 994  */
 995 void WINAPI FreeProcInstance16( FARPROC16 func )
 996 {
 997     TRACE("(%08lx)\n", (DWORD)func );
 998     TASK_FreeThunk( GetCurrentTask(), (SEGPTR)func );
 999 }
1000
1001 /**********************************************************************
1002  *          TASK_GetCodeSegment
1003  *
1004  * Helper function for GetCodeHandle/GetCodeInfo: Retrieve the module
1005  * and logical segment number of a given code segment.
1006  *
1007  * 'proc' either *is* already a pair of module handle and segment number,
1008  * in which case there's nothing to do.  Otherwise, it is a pointer to
1009  * a function, and we need to retrieve the code segment.  If the pointer
1010  * happens to point to a thunk, we'll retrieve info about the code segment
1011  * where the function pointed to by the thunk resides, not the thunk itself.
1012  *
1013  * FIXME: if 'proc' is a SNOOP16 return stub, we should retrieve info about
1014  *        the function the snoop code will return to ...
1015  *
1016  */
1017 static BOOL TASK_GetCodeSegment( FARPROC16 proc, NE_MODULE **ppModule,
1018                                  SEGTABLEENTRY **ppSeg, int *pSegNr )
1019 {
1020     NE_MODULE *pModule = NULL;
1021     SEGTABLEENTRY *pSeg = NULL;
1022     int segNr;
1023
1024     /* Try pair of module handle / segment number */
1025     pModule = (NE_MODULE *) GlobalLock16( HIWORD( proc ) );
1026     if ( pModule && pModule->magic == IMAGE_OS2_SIGNATURE )
1027     {
1028         segNr = LOWORD( proc );
1029         if ( segNr && segNr <= pModule->seg_count )
1030             pSeg = NE_SEG_TABLE( pModule ) + segNr-1;
1031     }
1032
1033     /* Try thunk or function */
1034     else
1035     {
1036         BYTE *thunk = (BYTE *)PTR_SEG_TO_LIN( proc );
1037         WORD selector;
1038
1039         if ((thunk[0] == 0xb8) && (thunk[3] == 0xea))
1040             selector = thunk[6] + (thunk[7] << 8);
1041         else
1042             selector = HIWORD( proc );
1043
1044         pModule = NE_GetPtr( GlobalHandle16( selector ) );
1045         pSeg = pModule? NE_SEG_TABLE( pModule ) : NULL;
1046
1047         if ( pModule )
1048             for ( segNr = 1; segNr <= pModule->seg_count; segNr++, pSeg++ )
1049                 if ( GlobalHandleToSel16(pSeg->hSeg) == selector )
1050                     break;
1051
1052         if ( pModule && segNr > pModule->seg_count )
1053             pSeg = NULL;
1054     }
1055
1056     /* Abort if segment not found */
1057
1058     if ( !pModule || !pSeg )
1059         return FALSE;
1060
1061     /* Return segment data */
1062
1063     if ( ppModule ) *ppModule = pModule;
1064     if ( ppSeg    ) *ppSeg    = pSeg;
1065     if ( pSegNr   ) *pSegNr   = segNr;
1066
1067     return TRUE;
1068 }
1069
1070 /**********************************************************************
1071  *          GetCodeHandle    (KERNEL.93)
1072  */
1073 HANDLE16 WINAPI GetCodeHandle16( FARPROC16 proc )
1074 {
1075     SEGTABLEENTRY *pSeg;
1076
1077     if ( !TASK_GetCodeSegment( proc, NULL, &pSeg, NULL ) )
1078         return (HANDLE16)0;
1079
1080     return pSeg->hSeg;
1081 }
1082
1083 /**********************************************************************
1084  *          GetCodeInfo    (KERNEL.104)
1085  */
1086 BOOL16 WINAPI GetCodeInfo16( FARPROC16 proc, SEGINFO *segInfo )
1087 {
1088     NE_MODULE *pModule;
1089     SEGTABLEENTRY *pSeg;
1090     int segNr;
1091
1092     if ( !TASK_GetCodeSegment( proc, &pModule, &pSeg, &segNr ) )
1093         return FALSE;
1094
1095     /* Fill in segment information */
1096
1097     segInfo->offSegment = pSeg->filepos;
1098     segInfo->cbSegment  = pSeg->size;
1099     segInfo->flags      = pSeg->flags;
1100     segInfo->cbAlloc    = pSeg->minsize;
1101     segInfo->h          = pSeg->hSeg;
1102     segInfo->alignShift = pModule->alignment;
1103
1104     if ( segNr == pModule->dgroup )
1105         segInfo->cbAlloc += pModule->heap_size + pModule->stack_size;
1106
1107     /* Return module handle in %es */
1108
1109     CURRENT_STACK16->es = GlobalHandleToSel16( pModule->self );
1110
1111     return TRUE;
1112 }
1113
1114
1115 /**********************************************************************
1116  *          DefineHandleTable16    (KERNEL.94)
1117  */
1118 BOOL16 WINAPI DefineHandleTable16( WORD wOffset )
1119 {
1120     return TRUE;  /* FIXME */
1121 }
1122
1123
1124 /***********************************************************************
1125  *           SetTaskQueue  (KERNEL.34)
1126  */
1127 HQUEUE16 WINAPI SetTaskQueue16( HTASK16 hTask, HQUEUE16 hQueue )
1128 {
1129     HQUEUE16 hPrev;
1130     TDB *pTask;
1131
1132     if (!hTask) hTask = GetCurrentTask();
1133     if (!(pTask = (TDB *)GlobalLock16( hTask ))) return 0;
1134
1135     hPrev = pTask->hQueue;
1136     pTask->hQueue = hQueue;
1137
1138     return hPrev;
1139 }
1140
1141
1142 /***********************************************************************
1143  *           GetTaskQueue  (KERNEL.35)
1144  */
1145 HQUEUE16 WINAPI GetTaskQueue16( HTASK16 hTask )
1146 {
1147     TDB *pTask;
1148
1149     if (!hTask) hTask = GetCurrentTask();
1150     if (!(pTask = (TDB *)GlobalLock16( hTask ))) return 0;
1151     return pTask->hQueue;
1152 }
1153
1154 /***********************************************************************
1155  *           SetThreadQueue  (KERNEL.463)
1156  */
1157 HQUEUE16 WINAPI SetThreadQueue16( DWORD thread, HQUEUE16 hQueue )
1158 {
1159     TEB *teb = thread? THREAD_IdToTEB( thread ) : NtCurrentTeb();
1160     HQUEUE16 oldQueue = teb? teb->queue : 0;
1161
1162     if ( teb )
1163     {
1164         teb->queue = hQueue;
1165
1166         if ( GetTaskQueue16( teb->htask16 ) == oldQueue )
1167             SetTaskQueue16( teb->htask16, hQueue );
1168     }
1169
1170     return oldQueue;
1171 }
1172
1173 /***********************************************************************
1174  *           GetThreadQueue  (KERNEL.464)
1175  */
1176 HQUEUE16 WINAPI GetThreadQueue16( DWORD thread )
1177 {
1178     TEB *teb = NULL;
1179     if ( !thread )
1180         teb = NtCurrentTeb();
1181     else if ( HIWORD(thread) )
1182         teb = THREAD_IdToTEB( thread );
1183     else if ( IsTask16( (HTASK16)thread ) )
1184         teb = ((TDB *)GlobalLock16( (HANDLE16)thread ))->teb;
1185
1186     return (HQUEUE16)(teb? teb->queue : 0);
1187 }
1188
1189 /***********************************************************************
1190  *           SetFastQueue  (KERNEL.624)
1191  */
1192 VOID WINAPI SetFastQueue16( DWORD thread, HANDLE hQueue )
1193 {
1194     TEB *teb = NULL;
1195     if ( !thread )
1196         teb = NtCurrentTeb();
1197     else if ( HIWORD(thread) )
1198         teb = THREAD_IdToTEB( thread );
1199     else if ( IsTask16( (HTASK16)thread ) )
1200         teb = ((TDB *)GlobalLock16( (HANDLE16)thread ))->teb;
1201
1202     if ( teb ) teb->queue = (HQUEUE16) hQueue;
1203 }
1204
1205 /***********************************************************************
1206  *           GetFastQueue  (KERNEL.625)
1207  */
1208 HANDLE WINAPI GetFastQueue16( void )
1209 {
1210     TEB *teb = NtCurrentTeb();
1211     if (!teb) return 0;
1212
1213     if (!teb->queue)
1214         Callout.InitThreadInput16( 0, THREAD_IsWin16(teb)? 4 : 5 );
1215
1216     if (!teb->queue)
1217         FIXME("(): should initialize thread-local queue, expect failure!\n" );
1218
1219     return (HANDLE)teb->queue;
1220 }
1221
1222 /***********************************************************************
1223  *           SwitchStackTo   (KERNEL.108)
1224  */
1225 void WINAPI SwitchStackTo16( WORD seg, WORD ptr, WORD top )
1226 {
1227     TDB *pTask;
1228     STACK16FRAME *oldFrame, *newFrame;
1229     INSTANCEDATA *pData;
1230     UINT16 copySize;
1231
1232     if (!(pTask = (TDB *)GlobalLock16( GetCurrentTask() ))) return;
1233     if (!(pData = (INSTANCEDATA *)GlobalLock16( seg ))) return;
1234     TRACE("old=%04x:%04x new=%04x:%04x\n",
1235           SELECTOROF( pTask->teb->cur_stack ),
1236           OFFSETOF( pTask->teb->cur_stack ), seg, ptr );
1237
1238     /* Save the old stack */
1239
1240     oldFrame = THREAD_STACK16( pTask->teb );
1241     /* pop frame + args and push bp */
1242     pData->old_ss_sp   = pTask->teb->cur_stack + sizeof(STACK16FRAME)
1243                            + 2 * sizeof(WORD);
1244     *(WORD *)PTR_SEG_TO_LIN(pData->old_ss_sp) = oldFrame->bp;
1245     pData->stacktop    = top;
1246     pData->stackmin    = ptr;
1247     pData->stackbottom = ptr;
1248
1249     /* Switch to the new stack */
1250
1251     /* Note: we need to take the 3 arguments into account; otherwise,
1252      * the stack will underflow upon return from this function.
1253      */
1254     copySize = oldFrame->bp - OFFSETOF(pData->old_ss_sp);
1255     copySize += 3 * sizeof(WORD) + sizeof(STACK16FRAME);
1256     pTask->teb->cur_stack = PTR_SEG_OFF_TO_SEGPTR( seg, ptr - copySize );
1257     newFrame = THREAD_STACK16( pTask->teb );
1258
1259     /* Copy the stack frame and the local variables to the new stack */
1260
1261     memmove( newFrame, oldFrame, copySize );
1262     newFrame->bp = ptr;
1263     *(WORD *)PTR_SEG_OFF_TO_LIN( seg, ptr ) = 0;  /* clear previous bp */
1264 }
1265
1266
1267 /***********************************************************************
1268  *           SwitchStackBack   (KERNEL.109)
1269  */
1270 void WINAPI SwitchStackBack16( CONTEXT86 *context )
1271 {
1272     STACK16FRAME *oldFrame, *newFrame;
1273     INSTANCEDATA *pData;
1274
1275     if (!(pData = (INSTANCEDATA *)GlobalLock16(SELECTOROF(NtCurrentTeb()->cur_stack))))
1276         return;
1277     if (!pData->old_ss_sp)
1278     {
1279         WARN("No previous SwitchStackTo\n" );
1280         return;
1281     }
1282     TRACE("restoring stack %04x:%04x\n",
1283           SELECTOROF(pData->old_ss_sp), OFFSETOF(pData->old_ss_sp) );
1284
1285     oldFrame = CURRENT_STACK16;
1286
1287     /* Pop bp from the previous stack */
1288
1289     BP_reg(context) = *(WORD *)PTR_SEG_TO_LIN(pData->old_ss_sp);
1290     pData->old_ss_sp += sizeof(WORD);
1291
1292     /* Switch back to the old stack */
1293
1294     NtCurrentTeb()->cur_stack = pData->old_ss_sp - sizeof(STACK16FRAME);
1295     SS_reg(context)  = SELECTOROF(pData->old_ss_sp);
1296     ESP_reg(context) = OFFSETOF(pData->old_ss_sp) - sizeof(DWORD); /*ret addr*/
1297     pData->old_ss_sp = 0;
1298
1299     /* Build a stack frame for the return */
1300
1301     newFrame = CURRENT_STACK16;
1302     newFrame->frame32     = oldFrame->frame32;
1303     newFrame->module_cs   = oldFrame->module_cs;
1304     newFrame->callfrom_ip = oldFrame->callfrom_ip;
1305     newFrame->entry_ip    = oldFrame->entry_ip;
1306 }
1307
1308
1309 /***********************************************************************
1310  *           GetTaskQueueDS16  (KERNEL.118)
1311  */
1312 void WINAPI GetTaskQueueDS16(void)
1313 {
1314     CURRENT_STACK16->ds = GlobalHandleToSel16( GetTaskQueue16(0) );
1315 }
1316
1317
1318 /***********************************************************************
1319  *           GetTaskQueueES16  (KERNEL.119)
1320  */
1321 void WINAPI GetTaskQueueES16(void)
1322 {
1323     CURRENT_STACK16->es = GlobalHandleToSel16( GetTaskQueue16(0) );
1324 }
1325
1326
1327 /***********************************************************************
1328  *           GetCurrentTask   (KERNEL.36)
1329  */
1330 HTASK16 WINAPI GetCurrentTask(void)
1331 {
1332     return NtCurrentTeb()->htask16;
1333 }
1334
1335 DWORD WINAPI WIN16_GetCurrentTask(void)
1336 {
1337     /* This is the version used by relay code; the first task is */
1338     /* returned in the high word of the result */
1339     return MAKELONG( GetCurrentTask(), hFirstTask );
1340 }
1341
1342
1343 /***********************************************************************
1344  *           GetCurrentPDB   (KERNEL.37)
1345  *
1346  * UNDOC: returns PSP of KERNEL in high word
1347  */
1348 DWORD WINAPI GetCurrentPDB16(void)
1349 {
1350     TDB *pTask;
1351
1352     if (!(pTask = (TDB *)GlobalLock16( GetCurrentTask() ))) return 0;
1353     return MAKELONG(pTask->hPDB, 0); /* FIXME */
1354 }
1355
1356
1357 /***********************************************************************
1358  *           GetCurPID16   (KERNEL.157)
1359  */
1360 DWORD WINAPI GetCurPID16( DWORD unused )
1361 {
1362     return 0;
1363 }
1364
1365
1366 /***********************************************************************
1367  *           GetInstanceData   (KERNEL.54)
1368  */
1369 INT16 WINAPI GetInstanceData16( HINSTANCE16 instance, WORD buffer, INT16 len )
1370 {
1371     char *ptr = (char *)GlobalLock16( instance );
1372     if (!ptr || !len) return 0;
1373     if ((int)buffer + len >= 0x10000) len = 0x10000 - buffer;
1374     memcpy( (char *)GlobalLock16(CURRENT_DS) + buffer, ptr + buffer, len );
1375     return len;
1376 }
1377
1378
1379 /***********************************************************************
1380  *           GetExeVersion   (KERNEL.105)
1381  */
1382 WORD WINAPI GetExeVersion16(void)
1383 {
1384     TDB *pTask;
1385
1386     if (!(pTask = (TDB *)GlobalLock16( GetCurrentTask() ))) return 0;
1387     return pTask->version;
1388 }
1389
1390
1391 /***********************************************************************
1392  *           SetErrorMode16   (KERNEL.107)
1393  */
1394 UINT16 WINAPI SetErrorMode16( UINT16 mode )
1395 {
1396     TDB *pTask;
1397     if (!(pTask = (TDB *)GlobalLock16( GetCurrentTask() ))) return 0;
1398     pTask->error_mode = mode;
1399     return SetErrorMode( mode );
1400 }
1401
1402
1403 /***********************************************************************
1404  *           GetDOSEnvironment   (KERNEL.131)
1405  */
1406 SEGPTR WINAPI GetDOSEnvironment16(void)
1407 {
1408     TDB *pTask;
1409
1410     if (!(pTask = (TDB *)GlobalLock16( GetCurrentTask() ))) return 0;
1411     return PTR_SEG_OFF_TO_SEGPTR( pTask->pdb.environment, 0 );
1412 }
1413
1414
1415 /***********************************************************************
1416  *           GetNumTasks   (KERNEL.152)
1417  */
1418 UINT16 WINAPI GetNumTasks16(void)
1419 {
1420     return nTaskCount;
1421 }
1422
1423
1424 /***********************************************************************
1425  *           GetTaskDS   (KERNEL.155)
1426  *
1427  * Note: this function apparently returns a DWORD with LOWORD == HIWORD.
1428  * I don't think we need to bother with this.
1429  */
1430 HINSTANCE16 WINAPI GetTaskDS16(void)
1431 {
1432     TDB *pTask;
1433
1434     if (!(pTask = (TDB *)GlobalLock16( GetCurrentTask() ))) return 0;
1435     return GlobalHandleToSel16(pTask->hInstance);
1436 }
1437
1438 /***********************************************************************
1439  *           GetDummyModuleHandleDS   (KERNEL.602)
1440  */
1441 WORD WINAPI GetDummyModuleHandleDS16(void)
1442 {
1443     TDB *pTask;
1444     WORD selector;
1445
1446     if (!(pTask = (TDB *)GlobalLock16( GetCurrentTask() ))) return 0;
1447     if (!(pTask->flags & TDBF_WIN32)) return 0;
1448     selector = GlobalHandleToSel16( pTask->hModule );
1449     CURRENT_DS = selector;
1450     return selector;
1451 }
1452
1453 /***********************************************************************
1454  *           IsTask   (KERNEL.320)
1455  */
1456 BOOL16 WINAPI IsTask16( HTASK16 hTask )
1457 {
1458     TDB *pTask;
1459
1460     if (!(pTask = (TDB *)GlobalLock16( hTask ))) return FALSE;
1461     if (GlobalSize16( hTask ) < sizeof(TDB)) return FALSE;
1462     return (pTask->magic == TDB_MAGIC);
1463 }
1464
1465
1466 /***********************************************************************
1467  *           IsWinOldApTask16   (KERNEL.158)
1468  */
1469 BOOL16 WINAPI IsWinOldApTask16( HTASK16 hTask )
1470 {
1471     /* should return bit 0 of byte 0x48 in PSP */
1472     return FALSE;
1473 }
1474
1475 /***********************************************************************
1476  *           SetTaskSignalProc   (KERNEL.38)
1477  */
1478 FARPROC16 WINAPI SetTaskSignalProc( HTASK16 hTask, FARPROC16 proc )
1479 {
1480     TDB *pTask;
1481     FARPROC16 oldProc;
1482
1483     if (!hTask) hTask = GetCurrentTask();
1484     if (!(pTask = (TDB *)GlobalLock16( hTask ))) return NULL;
1485     oldProc = pTask->userhandler;
1486     pTask->userhandler = proc;
1487     return oldProc;
1488 }
1489
1490 /***********************************************************************
1491  *           TASK_CallTaskSignalProc
1492  */
1493 /* ### start build ### */
1494 extern WORD CALLBACK TASK_CallTo16_word_wwwww(FARPROC16,WORD,WORD,WORD,WORD,WORD);
1495 /* ### stop build ### */
1496 void TASK_CallTaskSignalProc( UINT16 uCode, HANDLE16 hTaskOrModule )
1497 {
1498     TDB *pTask = (TDB *)GlobalLock16( GetCurrentTask() );
1499     if ( !pTask || !pTask->userhandler ) return;
1500
1501     TASK_CallTo16_word_wwwww( pTask->userhandler,
1502                               hTaskOrModule, uCode, 0,
1503                               pTask->hInstance, pTask->hQueue );
1504 }
1505
1506 /***********************************************************************
1507  *           SetSigHandler   (KERNEL.140)
1508  */
1509 WORD WINAPI SetSigHandler16( FARPROC16 newhandler, FARPROC16* oldhandler,
1510                            UINT16 *oldmode, UINT16 newmode, UINT16 flag )
1511 {
1512     FIXME("(%p,%p,%p,%d,%d), unimplemented.\n",
1513           newhandler,oldhandler,oldmode,newmode,flag );
1514
1515     if (flag != 1) return 0;
1516     if (!newmode) newhandler = NULL;  /* Default handler */
1517     if (newmode != 4)
1518     {
1519         TDB *pTask;
1520
1521         if (!(pTask = (TDB *)GlobalLock16( GetCurrentTask() ))) return 0;
1522         if (oldmode) *oldmode = pTask->signal_flags;
1523         pTask->signal_flags = newmode;
1524         if (oldhandler) *oldhandler = pTask->sighandler;
1525         pTask->sighandler = newhandler;
1526     }
1527     return 0;
1528 }
1529
1530
1531 /***********************************************************************
1532  *           GlobalNotify   (KERNEL.154)
1533  *
1534  * Note that GlobalNotify does _not_ return the old NotifyProc
1535  * -- contrary to LocalNotify !!
1536  */
1537 VOID WINAPI GlobalNotify16( FARPROC16 proc )
1538 {
1539     TDB *pTask;
1540
1541     if (!(pTask = (TDB *)GlobalLock16( GetCurrentTask() ))) return;
1542     pTask->discardhandler = proc;
1543 }
1544
1545
1546 /***********************************************************************
1547  *           GetExePtr   (KERNEL.133)
1548  */
1549 static inline HMODULE16 GetExePtrHelper( HANDLE16 handle, HTASK16 *hTask )
1550 {
1551     char *ptr;
1552     HANDLE16 owner;
1553
1554       /* Check for module handle */
1555
1556     if (!(ptr = GlobalLock16( handle ))) return 0;
1557     if (((NE_MODULE *)ptr)->magic == IMAGE_OS2_SIGNATURE) return handle;
1558
1559       /* Search for this handle inside all tasks */
1560
1561     *hTask = hFirstTask;
1562     while (*hTask)
1563     {
1564         TDB *pTask = (TDB *)GlobalLock16( *hTask );
1565         if ((*hTask == handle) ||
1566             (pTask->hInstance == handle) ||
1567             (pTask->hQueue == handle) ||
1568             (pTask->hPDB == handle)) return pTask->hModule;
1569         *hTask = pTask->hNext;
1570     }
1571
1572       /* Check the owner for module handle */
1573
1574     owner = FarGetOwner16( handle );
1575     if (!(ptr = GlobalLock16( owner ))) return 0;
1576     if (((NE_MODULE *)ptr)->magic == IMAGE_OS2_SIGNATURE) return owner;
1577
1578       /* Search for the owner inside all tasks */
1579
1580     *hTask = hFirstTask;
1581     while (*hTask)
1582     {
1583         TDB *pTask = (TDB *)GlobalLock16( *hTask );
1584         if ((*hTask == owner) ||
1585             (pTask->hInstance == owner) ||
1586             (pTask->hQueue == owner) ||
1587             (pTask->hPDB == owner)) return pTask->hModule;
1588         *hTask = pTask->hNext;
1589     }
1590
1591     return 0;
1592 }
1593
1594 HMODULE16 WINAPI WIN16_GetExePtr( HANDLE16 handle )
1595 {
1596     HTASK16 hTask = 0;
1597     HMODULE16 hModule = GetExePtrHelper( handle, &hTask );
1598     STACK16FRAME *frame = CURRENT_STACK16;
1599     frame->ecx = hModule;
1600     if (hTask) frame->es = hTask;
1601     return hModule;
1602 }
1603
1604 HMODULE16 WINAPI GetExePtr( HANDLE16 handle )
1605 {
1606     HTASK16 hTask = 0;
1607     return GetExePtrHelper( handle, &hTask );
1608 }
1609
1610
1611 /***********************************************************************
1612  *           TaskFirst   (TOOLHELP.63)
1613  */
1614 BOOL16 WINAPI TaskFirst16( TASKENTRY *lpte )
1615 {
1616     lpte->hNext = hFirstTask;
1617     return TaskNext16( lpte );
1618 }
1619
1620
1621 /***********************************************************************
1622  *           TaskNext   (TOOLHELP.64)
1623  */
1624 BOOL16 WINAPI TaskNext16( TASKENTRY *lpte )
1625 {
1626     TDB *pTask;
1627     INSTANCEDATA *pInstData;
1628
1629     TRACE_(toolhelp)("(%p): task=%04x\n", lpte, lpte->hNext );
1630     if (!lpte->hNext) return FALSE;
1631     pTask = (TDB *)GlobalLock16( lpte->hNext );
1632     if (!pTask || pTask->magic != TDB_MAGIC) return FALSE;
1633     pInstData = (INSTANCEDATA *)PTR_SEG_OFF_TO_LIN( GlobalHandleToSel16(pTask->hInstance), 0 );
1634     lpte->hTask         = lpte->hNext;
1635     lpte->hTaskParent   = pTask->hParent;
1636     lpte->hInst         = pTask->hInstance;
1637     lpte->hModule       = pTask->hModule;
1638     lpte->wSS           = SELECTOROF( pTask->teb->cur_stack );
1639     lpte->wSP           = OFFSETOF( pTask->teb->cur_stack );
1640     lpte->wStackTop     = pInstData->stacktop;
1641     lpte->wStackMinimum = pInstData->stackmin;
1642     lpte->wStackBottom  = pInstData->stackbottom;
1643     lpte->wcEvents      = pTask->nEvents;
1644     lpte->hQueue        = pTask->hQueue;
1645     lstrcpynA( lpte->szModule, pTask->module_name, sizeof(lpte->szModule) );
1646     lpte->wPSPOffset    = 0x100;  /*??*/
1647     lpte->hNext         = pTask->hNext;
1648     return TRUE;
1649 }
1650
1651
1652 /***********************************************************************
1653  *           TaskFindHandle   (TOOLHELP.65)
1654  */
1655 BOOL16 WINAPI TaskFindHandle16( TASKENTRY *lpte, HTASK16 hTask )
1656 {
1657     lpte->hNext = hTask;
1658     return TaskNext16( lpte );
1659 }
1660
1661
1662 /***********************************************************************
1663  *           GetAppCompatFlags16   (KERNEL.354)
1664  */
1665 DWORD WINAPI GetAppCompatFlags16( HTASK16 hTask )
1666 {
1667     return GetAppCompatFlags( hTask );
1668 }
1669
1670
1671 /***********************************************************************
1672  *           GetAppCompatFlags   (USER32.206)
1673  */
1674 DWORD WINAPI GetAppCompatFlags( HTASK hTask )
1675 {
1676     TDB *pTask;
1677
1678     if (!hTask) hTask = GetCurrentTask();
1679     if (!(pTask=(TDB *)GlobalLock16( (HTASK16)hTask ))) return 0;
1680     if (GlobalSize16(hTask) < sizeof(TDB)) return 0;
1681     return pTask->compat_flags;
1682 }