loader/task.c

   1 /*
   2  * Task functions
   3  *
   4  * Copyright 1995 Alexandre Julliard
   5  */
   6
   7 #include <stdio.h>
   8 #include <stdlib.h>
   9 #include <string.h>
  10 #include "windows.h"
  11 #include "task.h"
  12 #include "callback.h"
  13 #include "global.h"
  14 #include "instance.h"
  15 #include "miscemu.h"
  16 #include "module.h"
  17 #include "neexe.h"
  18 #include "selectors.h"
  19 #include "toolhelp.h"
  20 #include "wine.h"
  21 #include "stddebug.h"
  22 #include "debug.h"
  23
  24   /* Min. number of thunks allocated when creating a new segment */
  25 #define MIN_THUNKS  32
  26
  27   /* 32-bit stack size for each task */
  28   /* Must not be greater than 64k, or MAKE_SEGPTR won't work */
  29 #define STACK32_SIZE 0x10000
  30
  31
  32 static HTASK hFirstTask = 0;
  33 static HTASK hCurrentTask = 0;
  34 static HTASK hTaskToKill = 0;
  35 static HTASK hLockedTask = 0;
  36 static WORD nTaskCount = 0;
  37
  38   /* TASK_Reschedule() 16-bit entry point */
  39 static FARPROC TASK_RescheduleProc;
  40
  41 #define TASK_SCHEDULE()  CallTo16_word_(TASK_RescheduleProc,0)
  42
  43
  44 /***********************************************************************
  45  *           TASK_Init
  46  */
  47 BOOL TASK_Init(void)
  48 {
  49     TASK_RescheduleProc = (FARPROC)GetWndProcEntry16( "TASK_Reschedule" );
  50     return TRUE;
  51 }
  52
  53
  54 /***********************************************************************
  55  *           TASK_LinkTask
  56  */
  57 static void TASK_LinkTask( HTASK hTask )
  58 {
  59     HTASK *prevTask;
  60     TDB *pTask;
  61
  62     if (!(pTask = (TDB *)GlobalLock( hTask ))) return;
  63     prevTask = &hFirstTask;
  64     while (*prevTask)
  65     {
  66         TDB *prevTaskPtr = (TDB *)GlobalLock( *prevTask );
  67         if (prevTaskPtr->priority >= pTask->priority) break;
  68         prevTask = &prevTaskPtr->hNext;
  69     }
  70     pTask->hNext = *prevTask;
  71     *prevTask = hTask;
  72     nTaskCount++;
  73 }
  74
  75
  76 /***********************************************************************
  77  *           TASK_UnlinkTask
  78  */
  79 static void TASK_UnlinkTask( HTASK hTask )
  80 {
  81     HTASK *prevTask;
  82     TDB *pTask;
  83
  84     prevTask = &hFirstTask;
  85     while (*prevTask && (*prevTask != hTask))
  86     {
  87         pTask = (TDB *)GlobalLock( *prevTask );
  88         prevTask = &pTask->hNext;
  89     }
  90     if (*prevTask)
  91     {
  92         pTask = (TDB *)GlobalLock( *prevTask );
  93         *prevTask = pTask->hNext;
  94         pTask->hNext = 0;
  95         nTaskCount--;
  96     }
  97 }
  98
  99
 100 /***********************************************************************
 101  *           TASK_CreateThunks
 102  *
 103  * Create a thunk free-list in segment 'handle', starting from offset 'offset'
 104  * and containing 'count' entries.
 105  */
 106 static void TASK_CreateThunks( HGLOBAL handle, WORD offset, WORD count )
 107 {
 108     int i;
 109     WORD free;
 110     THUNKS *pThunk;
 111
 112     pThunk = (THUNKS *)((BYTE *)GlobalLock( handle ) + offset);
 113     pThunk->next = 0;
 114     pThunk->magic = THUNK_MAGIC;
 115     pThunk->free = (int)&pThunk->thunks - (int)pThunk;
 116     free = pThunk->free;
 117     for (i = 0; i < count-1; i++)
 118     {
 119         free += 8;  /* Offset of next thunk */
 120         pThunk->thunks[4*i] = free;
 121     }
 122     pThunk->thunks[4*i] = 0;  /* Last thunk */
 123 }
 124
 125
 126 /***********************************************************************
 127  *           TASK_AllocThunk
 128  *
 129  * Allocate a thunk for MakeProcInstance().
 130  */
 131 static SEGPTR TASK_AllocThunk( HTASK hTask )
 132 {
 133     TDB *pTask;
 134     THUNKS *pThunk;
 135     WORD sel, base;
 136
 137     if (!(pTask = (TDB *)GlobalLock( hTask ))) return 0;
 138     sel = pTask->hCSAlias;
 139     pThunk = &pTask->thunks;
 140     base = (int)pThunk - (int)pTask;
 141     while (!pThunk->free)
 142     {
 143         sel = pThunk->next;
 144         if (!sel)  /* Allocate a new segment */
 145         {
 146             sel = GLOBAL_Alloc( GMEM_FIXED, sizeof(THUNKS) + (MIN_THUNKS-1)*8,
 147                                 pTask->hPDB, TRUE, FALSE, FALSE );
 148             if (!sel) return (SEGPTR)0;
 149             TASK_CreateThunks( sel, 0, MIN_THUNKS );
 150             pThunk->next = sel;
 151         }
 152         pThunk = (THUNKS *)GlobalLock( sel );
 153         base = 0;
 154     }
 155     base += pThunk->free;
 156     pThunk->free = *(WORD *)((BYTE *)pThunk + pThunk->free);
 157     return MAKELONG( base, sel );
 158 }
 159
 160
 161 /***********************************************************************
 162  *           TASK_FreeThunk
 163  *
 164  * Free a MakeProcInstance() thunk.
 165  */
 166 static BOOL TASK_FreeThunk( HTASK hTask, SEGPTR thunk )
 167 {
 168     TDB *pTask;
 169     THUNKS *pThunk;
 170     WORD sel, base;
 171
 172     if (!(pTask = (TDB *)GlobalLock( hTask ))) return 0;
 173     sel = pTask->hCSAlias;
 174     pThunk = &pTask->thunks;
 175     base = (int)pThunk - (int)pTask;
 176     while (sel && (sel != HIWORD(thunk)))
 177     {
 178         sel = pThunk->next;
 179         pThunk = (THUNKS *)GlobalLock( sel );
 180         base = 0;
 181     }
 182     if (!sel) return FALSE;
 183     *(WORD *)((BYTE *)pThunk + LOWORD(thunk) - base) = pThunk->free;
 184     pThunk->free = LOWORD(thunk) - base;
 185     return TRUE;
 186 }
 187
 188
 189 /***********************************************************************
 190  *           TASK_CallToStart
 191  *
 192  * 32-bit entry point for a new task. This function is responsible for
 193  * setting up the registers and jumping to the 16-bit entry point.
 194  */
 195 static void TASK_CallToStart(void)
 196 {
 197     int cs_reg, ds_reg, ip_reg;
 198     TDB *pTask = (TDB *)GlobalLock( hCurrentTask );
 199     NE_MODULE *pModule = (NE_MODULE *)GlobalLock( pTask->hModule );
 200     SEGTABLEENTRY *pSegTable = NE_SEG_TABLE( pModule );
 201
 202     /* Registers at initialization must be:
 203      * ax   zero
 204      * bx   stack size in bytes
 205      * cx   heap size in bytes
 206      * si   previous app instance
 207      * di   current app instance
 208      * bp   zero
 209      * es   selector to the PSP
 210      * ds   dgroup of the application
 211      * ss   stack selector
 212      * sp   top of the stack
 213      */
 214
 215     cs_reg = pSegTable[pModule->cs - 1].selector;
 216     ip_reg = pModule->ip;
 217     ds_reg = pSegTable[pModule->dgroup - 1].selector;
 218     IF1632_Saved16_ss = pTask->ss;
 219     IF1632_Saved16_sp = pTask->sp;
 220     dprintf_task( stddeb, "Starting main program: cs:ip=%04x:%04x ds=%04x ss:sp=%04x:%04x\n",
 221                  cs_reg, ip_reg, ds_reg,
 222                  IF1632_Saved16_ss, IF1632_Saved16_sp);
 223     CallTo16_regs_( (FARPROC)(cs_reg << 16 | ip_reg), ds_reg,
 224                    pTask->hPDB /*es*/, 0 /*bp*/, 0 /*ax*/,
 225                    pModule->stack_size /*bx*/, pModule->heap_size /*cx*/,
 226                    0 /*dx*/, 0 /*si*/, ds_reg /*di*/ );
 227     /* This should never return */
 228     fprintf( stderr, "TASK_CallToStart: Main program returned!\n" );
 229     exit(1);
 230 }
 231
 232
 233 /***********************************************************************
 234  *           TASK_CreateTask
 235  */
 236 HTASK TASK_CreateTask( HMODULE hModule, HANDLE hInstance, HANDLE hPrevInstance,
 237                        HANDLE hEnvironment, char *cmdLine, WORD cmdShow )
 238 {
 239     HTASK hTask;
 240     TDB *pTask;
 241     NE_MODULE *pModule;
 242     SEGTABLEENTRY *pSegTable;
 243     LPSTR name;
 244     char *stack16Top, *stack32Top;
 245     STACK16FRAME *frame16;
 246     STACK32FRAME *frame32;
 247     extern DWORD CALL16_RetAddr_word;
 248
 249     if (!(pModule = (NE_MODULE *)GlobalLock( hModule ))) return 0;
 250     pSegTable = NE_SEG_TABLE( pModule );
 251
 252       /* Allocate the task structure */
 253
 254     hTask = GLOBAL_Alloc( GMEM_FIXED | GMEM_ZEROINIT, sizeof(TDB),
 255                           hModule, FALSE, FALSE, FALSE );
 256     if (!hTask) return 0;
 257     pTask = (TDB *)GlobalLock( hTask );
 258
 259       /* Fill the task structure */
 260
 261     pTask->nEvents       = 1;  /* So the task can be started */
 262     pTask->hSelf         = hTask;
 263     pTask->flags         = 0;
 264     pTask->version       = pModule->expected_version;
 265     pTask->hInstance     = hInstance;
 266     pTask->hPrevInstance = hPrevInstance;
 267     pTask->hModule       = hModule;
 268     pTask->hParent       = hCurrentTask;
 269     pTask->curdrive      = 'C' - 'A' + 0x80;
 270     pTask->magic         = TDB_MAGIC;
 271     pTask->nCmdShow      = cmdShow;
 272     strcpy( pTask->curdir, "WINDOWS" );
 273
 274       /* Create the thunks block */
 275
 276     TASK_CreateThunks( hTask, (int)&pTask->thunks - (int)pTask, 7 );
 277
 278       /* Copy the module name */
 279
 280     name = MODULE_GetModuleName( hModule );
 281     strncpy( pTask->module_name, name, sizeof(pTask->module_name) );
 282
 283       /* Fill the PDB */
 284
 285     pTask->pdb.int20 = 0x20cd;
 286     pTask->pdb.dispatcher[0] = 0x9a;  /* ljmp */
 287     *(DWORD *)&pTask->pdb.dispatcher[1] = MODULE_GetEntryPoint( GetModuleHandle("KERNEL"), 102 );  /* KERNEL.102 is DOS3Call() */
 288     pTask->pdb.savedint22 = INT_GetHandler( 0x22 );
 289     pTask->pdb.savedint23 = INT_GetHandler( 0x23 );
 290     pTask->pdb.savedint24 = INT_GetHandler( 0x24 );
 291     pTask->pdb.environment = hEnvironment;
 292     strncpy( pTask->pdb.cmdLine + 1, cmdLine, 126 );
 293     pTask->pdb.cmdLine[127] = '\0';
 294     pTask->pdb.cmdLine[0] = strlen( pTask->pdb.cmdLine + 1 );
 295
 296       /* Get the compatibility flags */
 297
 298     pTask->compat_flags = GetProfileInt( name, "Compatibility", 0 );
 299
 300       /* Allocate a selector for the PDB */
 301
 302     pTask->hPDB = GLOBAL_CreateBlock( GMEM_FIXED, &pTask->pdb, sizeof(PDB),
 303                                       hModule, FALSE, FALSE, FALSE );
 304
 305       /* Allocate a code segment alias for the TDB */
 306
 307     pTask->hCSAlias = GLOBAL_CreateBlock( GMEM_FIXED, (void *)pTask,
 308                                           sizeof(TDB), pTask->hPDB, TRUE,
 309                                           FALSE, FALSE );
 310
 311       /* Set the owner of the environment block */
 312
 313     FarSetOwner( pTask->pdb.environment, pTask->hPDB );
 314
 315       /* Default DTA overwrites command-line */
 316
 317     pTask->dta = MAKELONG( (int)&pTask->pdb.cmdLine - (int)&pTask->pdb,
 318                            pTask->hPDB );
 319
 320       /* Allocate the 32-bit stack */
 321
 322     pTask->hStack32 = GLOBAL_Alloc( GMEM_FIXED, STACK32_SIZE, pTask->hPDB,
 323                                     FALSE, FALSE, FALSE );
 324
 325       /* Create the 32-bit stack frame */
 326
 327     stack32Top = (char*)GlobalLock(pTask->hStack32) + STACK32_SIZE;
 328     frame32 = (STACK32FRAME *)stack32Top - 1;
 329     frame32->saved_esp = (DWORD)stack32Top;
 330     frame32->edi = 0;
 331     frame32->esi = 0;
 332     frame32->edx = 0;
 333     frame32->ecx = 0;
 334     frame32->ebx = 0;
 335     frame32->ebp = 0;
 336     frame32->retaddr = (DWORD)TASK_CallToStart;
 337     frame32->codeselector = WINE_CODE_SELECTOR;
 338     pTask->esp = (DWORD)frame32;
 339
 340       /* Create the 16-bit stack frame */
 341
 342     pTask->ss = hInstance;
 343     pTask->sp = (pModule->sp != 0) ? pModule->sp :
 344                 pSegTable[pModule->ss-1].minsize + pModule->stack_size;
 345     stack16Top = (char *)PTR_SEG_OFF_TO_LIN( pTask->ss, pTask->sp );
 346     frame16 = (STACK16FRAME *)stack16Top - 1;
 347     frame16->saved_ss = pTask->ss;
 348     frame16->saved_sp = pTask->sp;
 349     frame16->ds = pTask->hInstance;
 350     frame16->entry_point = 0;
 351     frame16->ordinal_number = 24;  /* WINPROCS.24 is TASK_Reschedule */
 352     frame16->dll_id = 24; /* WINPROCS */
 353     frame16->bp = 0;
 354     frame16->ip = LOWORD( CALL16_RetAddr_word );
 355     frame16->cs = HIWORD( CALL16_RetAddr_word );
 356     pTask->sp -= sizeof(STACK16FRAME);
 357
 358       /* If there's no 16-bit stack yet, use a part of the new task stack */
 359       /* This is only needed to have a stack to switch from on the first  */
 360       /* call to DirectedYield(). */
 361
 362     if (!IF1632_Saved16_ss)
 363     {
 364         IF1632_Saved16_ss = pTask->ss;
 365         IF1632_Saved16_sp = pTask->sp;
 366     }
 367
 368       /* Add the task to the linked list */
 369
 370     TASK_LinkTask( hTask );
 371
 372     dprintf_task( stddeb, "CreateTask: module='%s' cmdline='%s' task=%04x\n",
 373                   name, cmdLine, hTask );
 374
 375     return hTask;
 376 }
 377
 378
 379 /***********************************************************************
 380  *           TASK_DeleteTask
 381  */
 382 void TASK_DeleteTask( HTASK hTask )
 383 {
 384     TDB *pTask;
 385
 386     if (!(pTask = (TDB *)GlobalLock( hTask ))) return;
 387
 388       /* Free the task module */
 389
 390     FreeModule( pTask->hModule );
 391
 392       /* Free all memory used by this task (including the 32-bit stack, */
 393       /* the environment block and the thunk segments). */
 394
 395     GlobalFreeAll( pTask->hPDB );
 396
 397       /* Free the selector aliases */
 398
 399     GLOBAL_FreeBlock( pTask->hCSAlias );
 400     GLOBAL_FreeBlock( pTask->hPDB );
 401
 402       /* Free the task structure itself */
 403
 404     GlobalFree( hTask );
 405 }
 406
 407
 408 /***********************************************************************
 409  *           TASK_KillCurrentTask
 410  *
 411  * Kill the currently running task. As it's not possible to kill the
 412  * current task like this, it is simply marked for destruction, and will
 413  * be killed when either TASK_Reschedule or this function is called again
 414  * in the context of another task.
 415  */
 416 void TASK_KillCurrentTask( int exitCode )
 417 {
 418     if (hTaskToKill && (hTaskToKill != hCurrentTask))
 419     {
 420         /* If another task is already marked for destruction, */
 421         /* we call kill it now, as we are in another context. */
 422         TASK_DeleteTask( hTaskToKill );
 423     }
 424
 425     if (nTaskCount <= 1)
 426     {
 427         dprintf_task( stddeb, "Killing the last task, exiting\n" );
 428         exit(0);
 429     }
 430
 431     /* Remove the task from the list to be sure we never switch back to it */
 432     TASK_UnlinkTask( hCurrentTask );
 433
 434     hTaskToKill = hCurrentTask;
 435     hLockedTask = 0;
 436     Yield();
 437     /* We never return from Yield() */
 438 }
 439
 440
 441 /***********************************************************************
 442  *           TASK_Reschedule
 443  *
 444  * This is where all the magic of task-switching happens!
 445  *
 446  * This function should only be called via the TASK_SCHEDULE() macro, to make
 447  * sure that all the context is saved correctly.
 448  */
 449 void TASK_Reschedule(void)
 450 {
 451     TDB *pOldTask = NULL, *pNewTask;
 452     HTASK hTask = 0;
 453
 454       /* First check if there's a task to kill */
 455
 456     if (hTaskToKill && (hTaskToKill != hCurrentTask))
 457         TASK_DeleteTask( hTaskToKill );
 458
 459       /* If current task is locked, simply return */
 460
 461     if (hLockedTask) return;
 462
 463       /* Find a task to yield to */
 464
 465     pOldTask = (TDB *)GlobalLock( hCurrentTask );
 466     if (pOldTask && pOldTask->hYieldTo)
 467     {
 468         /* If a task is stored in hYieldTo of the current task (put there */
 469         /* by DirectedYield), yield to it only if it has events pending.  */
 470         hTask = pOldTask->hYieldTo;
 471         if (!(pNewTask = (TDB *)GlobalLock( hTask )) || !pNewTask->nEvents)
 472             hTask = 0;
 473     }
 474
 475     if (!hTask)
 476     {
 477         hTask = hFirstTask;
 478         while (hTask)
 479         {
 480             pNewTask = (TDB *)GlobalLock( hTask );
 481             if (pNewTask->nEvents && (hTask != hCurrentTask)) break;
 482             hTask = pNewTask->hNext;
 483         }
 484     }
 485
 486      /* If there's a task to kill, switch to any other task, */
 487      /* even if it doesn't have events pending. */
 488
 489     if (!hTask && hTaskToKill) hTask = hFirstTask;
 490
 491     if (!hTask) return;  /* Do nothing */
 492
 493     pNewTask = (TDB *)GlobalLock( hTask );
 494     dprintf_task( stddeb, "Switching to task %04x (%.8s)\n",
 495                   hTask, pNewTask->module_name );
 496
 497       /* Save the stacks of the previous task (if any) */
 498
 499     if (pOldTask)
 500     {
 501         pOldTask->ss  = IF1632_Saved16_ss;
 502         pOldTask->sp  = IF1632_Saved16_sp;
 503         pOldTask->esp = IF1632_Saved32_esp;
 504     }
 505     else IF1632_Original32_esp = IF1632_Saved32_esp;
 506
 507      /* Make the task the last in the linked list (round-robin scheduling) */
 508
 509     pNewTask->priority++;
 510     TASK_UnlinkTask( hTask );
 511     TASK_LinkTask( hTask );
 512     pNewTask->priority--;
 513
 514       /* Switch to the new stack */
 515
 516     hCurrentTask = hTask;
 517     IF1632_Saved16_ss   = pNewTask->ss;
 518     IF1632_Saved16_sp   = pNewTask->sp;
 519     IF1632_Saved32_esp  = pNewTask->esp;
 520     IF1632_Stack32_base = WIN16_GlobalLock( pNewTask->hStack32 );
 521 }
 522
 523
 524 /***********************************************************************
 525  *           InitTask  (KERNEL.91)
 526  */
 527 void InitTask( struct sigcontext_struct context )
 528 {
 529     static int firstTask = 1;
 530     TDB *pTask;
 531     NE_MODULE *pModule;
 532     SEGTABLEENTRY *pSegTable;
 533     INSTANCEDATA *pinstance;
 534     LONG stacklow, stackhi;
 535
 536     context.sc_eax = 0;
 537     if (!(pTask = (TDB *)GlobalLock( hCurrentTask ))) return;
 538     if (!(pModule = (NE_MODULE *)GlobalLock( pTask->hModule ))) return;
 539
 540     if (firstTask)
 541     {
 542         extern BOOL WIDGETS_Init(void);
 543         extern BOOL WIN_CreateDesktopWindow(void);
 544
 545         /* Perform global initialisations that need a task context */
 546
 547           /* Initialize built-in window classes */
 548         if (!WIDGETS_Init()) return;
 549
 550           /* Create desktop window */
 551         if (!WIN_CreateDesktopWindow()) return;
 552
 553         firstTask = 0;
 554     }
 555
 556     NE_InitializeDLLs( pTask->hModule );
 557
 558     /* Registers on return are:
 559      * ax     1 if OK, 0 on error
 560      * cx     stack limit in bytes
 561      * dx     cmdShow parameter
 562      * si     instance handle of the previous instance
 563      * di     instance handle of the new task
 564      * es:bx  pointer to command-line inside PSP
 565      */
 566     context.sc_eax = 1;
 567     context.sc_ebx = 0x81;
 568     context.sc_ecx = pModule->stack_size;
 569     context.sc_edx = pTask->nCmdShow;
 570     context.sc_esi = pTask->hPrevInstance;
 571     context.sc_edi = pTask->hInstance;
 572     context.sc_es  = pTask->hPDB;
 573
 574     /* Initialize the local heap */
 575     if ( pModule->heap_size )
 576     {
 577         LocalInit( pTask->hInstance, 0, pModule->heap_size );
 578     }
 579
 580
 581     /* Initialize the INSTANCEDATA structure */
 582     pSegTable = NE_SEG_TABLE( pModule );
 583     stacklow = pSegTable[pModule->ss - 1].minsize;
 584     stackhi  = stacklow + pModule->stack_size;
 585     if (stackhi > 0xffff) stackhi = 0xffff;
 586     pinstance = (INSTANCEDATA *)PTR_SEG_OFF_TO_LIN(CURRENT_DS, 0);
 587     pinstance->stackbottom = stackhi; /* yup, that's right. Confused me too. */
 588     pinstance->stacktop    = stacklow;
 589     pinstance->stackmin    = IF1632_Saved16_sp;
 590 }
 591
 592
 593 /***********************************************************************
 594  *           WaitEvent  (KERNEL.30)
 595  */
 596 BOOL WaitEvent( HTASK hTask )
 597 {
 598     TDB *pTask;
 599
 600     if (!hTask) hTask = hCurrentTask;
 601     pTask = (TDB *)GlobalLock( hTask );
 602     if (pTask->nEvents > 0)
 603     {
 604         pTask->nEvents--;
 605         return FALSE;
 606     }
 607     TASK_SCHEDULE();
 608     /* When we get back here, we have an event (or the task is the only one) */
 609     if (pTask->nEvents > 0) pTask->nEvents--;
 610     return TRUE;
 611 }
 612
 613
 614 /***********************************************************************
 615  *           PostEvent  (KERNEL.31)
 616  */
 617 void PostEvent( HTASK hTask )
 618 {
 619     TDB *pTask;
 620
 621     if (!hTask) hTask = hCurrentTask;
 622     if (!(pTask = (TDB *)GlobalLock( hTask ))) return;
 623     pTask->nEvents++;
 624 }
 625
 626
 627 /***********************************************************************
 628  *           SetPriority  (KERNEL.32)
 629  */
 630 void SetPriority( HTASK hTask, int delta )
 631 {
 632     TDB *pTask;
 633     int newpriority;
 634
 635     if (!hTask) hTask = hCurrentTask;
 636     if (!(pTask = (TDB *)GlobalLock( hTask ))) return;
 637     newpriority = pTask->priority + delta;
 638     if (newpriority < -32) newpriority = -32;
 639     else if (newpriority > 15) newpriority = 15;
 640
 641     pTask->priority = newpriority + 1;
 642     TASK_UnlinkTask( hTask );
 643     TASK_LinkTask( hTask );
 644     pTask->priority--;
 645 }
 646
 647
 648 /***********************************************************************
 649  *           LockCurrentTask  (KERNEL.33)
 650  */
 651 HTASK LockCurrentTask( BOOL bLock )
 652 {
 653     if (bLock) hLockedTask = hCurrentTask;
 654     else hLockedTask = 0;
 655     return hLockedTask;
 656 }
 657
 658
 659 /***********************************************************************
 660  *           IsTaskLocked  (KERNEL.122)
 661  */
 662 WORD IsTaskLocked(void)
 663 {
 664     return hLockedTask;
 665 }
 666
 667
 668 /***********************************************************************
 669  *           OldYield  (KERNEL.117)
 670  */
 671 void OldYield(void)
 672 {
 673     TDB *pCurTask;
 674
 675     pCurTask = (TDB *)GlobalLock( hCurrentTask );
 676     if (pCurTask) pCurTask->nEvents++;  /* Make sure we get back here */
 677     TASK_SCHEDULE();
 678     if (pCurTask) pCurTask->nEvents--;
 679 }
 680
 681
 682 /***********************************************************************
 683  *           DirectedYield  (KERNEL.150)
 684  */
 685 void DirectedYield( HTASK hTask )
 686 {
 687     TDB *pCurTask;
 688
 689     if ((pCurTask = (TDB *)GlobalLock( hCurrentTask )) != NULL)
 690         pCurTask->hYieldTo = hTask;
 691
 692     OldYield();
 693 }
 694
 695
 696 /***********************************************************************
 697  *           Yield  (KERNEL.29)
 698  */
 699 void Yield(void)
 700 {
 701     DirectedYield( 0 );
 702 }
 703
 704
 705 /***********************************************************************
 706  *           MakeProcInstance  (KERNEL.51)
 707  */
 708 FARPROC MakeProcInstance( FARPROC func, HANDLE hInstance )
 709 {
 710     BYTE *thunk;
 711     SEGPTR thunkaddr;
 712
 713     thunkaddr = TASK_AllocThunk( hCurrentTask );
 714     if (!thunkaddr) return (FARPROC)0;
 715     thunk = PTR_SEG_TO_LIN( thunkaddr );
 716
 717     dprintf_task( stddeb, "MakeProcInstance(%08lx,%04x): got thunk %08lx\n",
 718                   (SEGPTR)func, hInstance, (SEGPTR)thunkaddr );
 719
 720     *thunk++ = 0xb8;    /* movw instance, %ax */
 721     *thunk++ = (BYTE)(hInstance & 0xff);
 722     *thunk++ = (BYTE)(hInstance >> 8);
 723     *thunk++ = 0xea;    /* ljmp func */
 724     *(DWORD *)thunk = (DWORD)func;
 725     return (FARPROC)thunkaddr;
 726 }
 727
 728
 729 /***********************************************************************
 730  *           FreeProcInstance  (KERNEL.52)
 731  */
 732 void FreeProcInstance( FARPROC func )
 733 {
 734     dprintf_task( stddeb, "FreeProcInstance(%08lx)\n", (SEGPTR)func );
 735     TASK_FreeThunk( hCurrentTask, (SEGPTR)func );
 736 }
 737
 738
 739 /**********************************************************************
 740  *          GetCodeHandle    (KERNEL.93)
 741  */
 742 HANDLE GetCodeHandle( FARPROC proc )
 743 {
 744     HANDLE handle;
 745     BYTE *thunk = (BYTE *)PTR_SEG_TO_LIN( proc );
 746
 747     /* Return the code segment containing 'proc'. */
 748     /* Not sure if this is really correct (shouldn't matter that much). */
 749
 750     /* Check if it is really a thunk */
 751     if ((thunk[0] == 0xb8) && (thunk[3] == 0xea))
 752         handle = GlobalHandle( thunk[6] + (thunk[7] << 8) );
 753     else
 754         handle = GlobalHandle( HIWORD(proc) );
 755
 756     printf( "STUB: GetCodeHandle(%08lx) returning %04x\n",
 757             (DWORD)proc, handle );
 758     return handle;
 759 }
 760
 761
 762 /***********************************************************************
 763  *           SetTaskQueue  (KERNEL.34)
 764  */
 765 HGLOBAL SetTaskQueue( HANDLE hTask, HGLOBAL hQueue )
 766 {
 767     HGLOBAL hPrev;
 768     TDB *pTask;
 769
 770     if (!hTask) hTask = hCurrentTask;
 771     if (!(pTask = (TDB *)GlobalLock( hTask ))) return 0;
 772     hPrev = pTask->hQueue;
 773     pTask->hQueue = hQueue;
 774     return hPrev;
 775 }
 776
 777
 778 /***********************************************************************
 779  *           GetTaskQueue  (KERNEL.35)
 780  */
 781 HGLOBAL GetTaskQueue( HANDLE hTask )
 782 {
 783     TDB *pTask;
 784
 785     if (!hTask) hTask = hCurrentTask;
 786     if (!(pTask = (TDB *)GlobalLock( hTask ))) return 0;
 787     return pTask->hQueue;
 788 }
 789
 790
 791 /***********************************************************************
 792  *           GetCurrentTask   (KERNEL.36)
 793  */
 794 HTASK GetCurrentTask(void)
 795 {
 796       /* Undocumented: first task is returned in high word */
 797     return MAKELONG( hCurrentTask, hFirstTask );
 798 }
 799
 800
 801 /***********************************************************************
 802  *           GetCurrentPDB   (KERNEL.37)
 803  */
 804 WORD GetCurrentPDB(void)
 805 {
 806     TDB *pTask;
 807
 808     if (!(pTask = (TDB *)GlobalLock( hCurrentTask ))) return 0;
 809     return pTask->hPDB;
 810 }
 811
 812
 813 /***********************************************************************
 814  *           GetInstanceData   (KERNEL.54)
 815  */
 816 int GetInstanceData( HANDLE instance, WORD buffer, int len )
 817 {
 818     char *ptr = (char *)GlobalLock( instance );
 819     if (!ptr || !len) return 0;
 820     if ((int)buffer + len >= 0x10000) len = 0x10000 - buffer;
 821     memcpy( ptr + buffer, (char *)GlobalLock( CURRENT_DS ) + buffer, len );
 822     return len;
 823 }
 824
 825
 826 /***********************************************************************
 827  *           GetNumTasks   (KERNEL.152)
 828  */
 829 WORD GetNumTasks(void)
 830 {
 831     return nTaskCount;
 832 }
 833
 834
 835 /***********************************************************************
 836  *           GetTaskDS   (KERNEL.155)
 837  */
 838 WORD GetTaskDS(void)
 839 {
 840     TDB *pTask;
 841
 842     if (!(pTask = (TDB *)GlobalLock( hCurrentTask ))) return 0;
 843     return pTask->hInstance;
 844 }
 845
 846
 847 /***********************************************************************
 848  *           IsTask   (KERNEL.320)
 849  */
 850 BOOL IsTask( HTASK hTask )
 851 {
 852     TDB *pTask;
 853
 854     if (!(pTask = (TDB *)GlobalLock( hTask ))) return FALSE;
 855     if (GlobalSize( hTask ) < sizeof(TDB)) return FALSE;
 856     return (pTask->magic == TDB_MAGIC);
 857 }
 858
 859
 860 /***********************************************************************
 861  *           GetExePtr   (KERNEL.133)
 862  */
 863 HMODULE GetExePtr( HANDLE handle )
 864 {
 865     char *ptr;
 866     HTASK hTask;
 867     HANDLE owner;
 868
 869       /* Check for module handle */
 870
 871     if (!(ptr = GlobalLock( handle ))) return 0;
 872     if (((NE_MODULE *)ptr)->magic == NE_SIGNATURE) return handle;
 873
 874       /* Check the owner for module handle */
 875
 876     owner = FarGetOwner( handle );
 877     if (!(ptr = GlobalLock( owner ))) return 0;
 878     if (((NE_MODULE *)ptr)->magic == NE_SIGNATURE) return owner;
 879
 880       /* Search for this handle and its owner inside all tasks */
 881
 882     hTask = hFirstTask;
 883     while (hTask)
 884     {
 885         TDB *pTask = (TDB *)GlobalLock( hTask );
 886         if ((hTask == handle) ||
 887             (pTask->hInstance == handle) ||
 888             (pTask->hQueue == handle) ||
 889             (pTask->hPDB == handle)) return pTask->hModule;
 890         if ((hTask == owner) ||
 891             (pTask->hInstance == owner) ||
 892             (pTask->hQueue == owner) ||
 893             (pTask->hPDB == owner)) return pTask->hModule;
 894     }
 895     return 0;
 896 }
 897
 898
 899 /***********************************************************************
 900  *           TaskFirst   (TOOLHELP.63)
 901  */
 902 BOOL TaskFirst( TASKENTRY *lpte )
 903 {
 904     lpte->hNext = hFirstTask;
 905     return TaskNext( lpte );
 906 }
 907
 908
 909 /***********************************************************************
 910  *           TaskNext   (TOOLHELP.64)
 911  */
 912 BOOL TaskNext( TASKENTRY *lpte )
 913 {
 914     TDB *pTask;
 915     INSTANCEDATA *pInstData;
 916
 917     dprintf_toolhelp( stddeb, "TaskNext(%p): task=%04x\n", lpte, lpte->hNext );
 918     if (!lpte->hNext) return FALSE;
 919     pTask = (TDB *)GlobalLock( lpte->hNext );
 920     if (!pTask || pTask->magic != TDB_MAGIC) return FALSE;
 921     pInstData = (INSTANCEDATA *)PTR_SEG_OFF_TO_LIN( pTask->hInstance, 0 );
 922     lpte->hTask         = lpte->hNext;
 923     lpte->hTaskParent   = pTask->hParent;
 924     lpte->hInst         = pTask->hInstance;
 925     lpte->hModule       = pTask->hModule;
 926     lpte->wSS           = pTask->ss;
 927     lpte->wSP           = pTask->sp;
 928     lpte->wStackTop     = pInstData->stacktop;
 929     lpte->wStackMinimum = pInstData->stackmin;
 930     lpte->wStackBottom  = pInstData->stackbottom;
 931     lpte->wcEvents      = pTask->nEvents;
 932     lpte->hQueue        = pTask->hQueue;
 933     strncpy( lpte->szModule, pTask->module_name, 8 );
 934     lpte->szModule[8]   = '\0';
 935     lpte->wPSPOffset    = 0x100;  /*??*/
 936     lpte->hNext         = pTask->hNext;
 937     return TRUE;
 938 }
 939
 940
 941 /***********************************************************************
 942  *           TaskFindHandle   (TOOLHELP.65)
 943  */
 944 BOOL TaskFindHandle( TASKENTRY *lpte, HTASK hTask )
 945 {
 946     lpte->hNext = hTask;
 947     return TaskNext( lpte );
 948 }