loader/dos/dosvm.c

   1 /*
   2  * DOS Virtual Machine
   3  *
   4  * Copyright 1998 Ove Kåven
   5  *
   6  * This code hasn't been completely cleaned up yet.
   7  */
   8
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #include <string.h>
  12 #include <errno.h>
  13 #include <fcntl.h>
  14 #include <signal.h>
  15 #include <unistd.h>
  16 #include <sys/time.h>
  17 #include <sys/types.h>
  18 #include <sys/stat.h>
  19
  20 #include "wine/winbase16.h"
  21 #include "winuser.h"
  22 #include "winnt.h"
  23 #include "sig_context.h"
  24 #include "msdos.h"
  25 #include "file.h"
  26 #include "miscemu.h"
  27 #include "debugger.h"
  28 #include "module.h"
  29 #include "task.h"
  30 #include "ldt.h"
  31 #include "dosexe.h"
  32 #include "dosmod.h"
  33 #include "debugtools.h"
  34
  35 DECLARE_DEBUG_CHANNEL(int)
  36 DECLARE_DEBUG_CHANNEL(module)
  37 DECLARE_DEBUG_CHANNEL(relay)
  38
  39 #ifdef MZ_SUPPORTED
  40
  41 #include <sys/mman.h>
  42 #include <sys/vm86.h>
  43
  44 #define IF_CLR(ctx) EFL_reg(ctx) &= ~VIF_MASK
  45 #define IF_ENABLED(ctx) (EFL_reg(ctx) & VIF_MASK)
  46 #define SET_PEND(ctx) EFL_reg(ctx) |= VIP_MASK
  47 #define CLR_PEND(ctx) EFL_reg(ctx) &= ~VIP_MASK
  48 #define IS_PEND(ctx) (EFL_reg(ctx) & VIP_MASK)
  49
  50 #undef TRY_PICRETURN
  51
  52 static void DOSVM_Dump( LPDOSTASK lpDosTask, int fn, int sig,
  53                         struct vm86plus_struct*VM86 )
  54 {
  55  unsigned iofs;
  56  BYTE*inst;
  57  int x;
  58
  59  switch (VM86_TYPE(fn)) {
  60   case VM86_SIGNAL:
  61    printf("Trapped signal %d\n",sig); break;
  62   case VM86_UNKNOWN:
  63    printf("Trapped unhandled GPF\n"); break;
  64   case VM86_INTx:
  65    printf("Trapped INT %02x\n",VM86_ARG(fn)); break;
  66   case VM86_STI:
  67    printf("Trapped STI\n"); break;
  68   case VM86_PICRETURN:
  69    printf("Trapped due to pending PIC request\n"); break;
  70   case VM86_TRAP:
  71    printf("Trapped debug request\n"); break;
  72   default:
  73    printf("Trapped unknown VM86 type %d arg %d\n",VM86_TYPE(fn),VM86_ARG(fn)); break;
  74  }
  75 #define REGS VM86->regs
  76  fprintf(stderr,"AX=%04lX CX=%04lX DX=%04lX BX=%04lX\n",REGS.eax,REGS.ecx,REGS.edx,REGS.ebx);
  77  fprintf(stderr,"SI=%04lX DI=%04lX SP=%04lX BP=%04lX\n",REGS.esi,REGS.edi,REGS.esp,REGS.ebp);
  78  fprintf(stderr,"CS=%04X DS=%04X ES=%04X SS=%04X\n",REGS.cs,REGS.ds,REGS.es,REGS.ss);
  79  fprintf(stderr,"IP=%04lX EFLAGS=%08lX\n",REGS.eip,REGS.eflags);
  80
  81  iofs=((DWORD)REGS.cs<<4)+REGS.eip;
  82 #undef REGS
  83  inst=(BYTE*)lpDosTask->img+iofs;
  84  printf("Opcodes:");
  85  for (x=0; x<8; x++) printf(" %02x",inst[x]);
  86  printf("\n");
  87 }
  88
  89 static int DOSVM_Int( int vect, PCONTEXT context, LPDOSTASK lpDosTask )
  90 {
  91  extern UINT16 DPMI_wrap_seg;
  92
  93  if (vect==0x31) {
  94   if (CS_reg(context)==DPMI_wrap_seg) {
  95    /* exit from real-mode wrapper */
  96    return -1;
  97   }
  98   /* we could probably move some other dodgy stuff here too from dpmi.c */
  99  }
 100  INT_RealModeInterrupt(vect,context);
 101  return 0;
 102 }
 103
 104 static void DOSVM_SimulateInt( int vect, PCONTEXT context, LPDOSTASK lpDosTask )
 105 {
 106   FARPROC16 handler=INT_GetRMHandler(vect);
 107
 108   if (SELECTOROF(handler)==0xf000) {
 109     /* if internal interrupt, call it directly */
 110     INT_RealModeInterrupt(vect,context);
 111   } else {
 112     WORD*stack=(WORD*)(V86BASE(context)+(((DWORD)SS_reg(context))<<4)+SP_reg(context));
 113     WORD flag=FL_reg(context);
 114
 115     if (IF_ENABLED(context)) flag|=IF_MASK;
 116     else flag&=~IF_MASK;
 117
 118     *(--stack)=flag;
 119     *(--stack)=CS_reg(context);
 120     *(--stack)=IP_reg(context);
 121     SP_reg(context)-=6;
 122     CS_reg(context)=SELECTOROF(handler);
 123     IP_reg(context)=OFFSETOF(handler);
 124     IF_CLR(context);
 125   }
 126 }
 127
 128 #define SHOULD_PEND(x) \
 129   (x && ((!lpDosTask->current) || (x->priority < lpDosTask->current->priority)))
 130
 131 static void DOSVM_SendQueuedEvent(PCONTEXT context, LPDOSTASK lpDosTask)
 132 {
 133   LPDOSEVENT event = lpDosTask->pending;
 134
 135   if (SHOULD_PEND(event)) {
 136     /* remove from "pending" list */
 137     lpDosTask->pending = event->next;
 138     /* process event */
 139     if (event->irq>=0) {
 140       /* it's an IRQ, move it to "current" list */
 141       event->next = lpDosTask->current;
 142       lpDosTask->current = event;
 143       TRACE_(int)("dispatching IRQ %d\n",event->irq);
 144       /* note that if DOSVM_SimulateInt calls an internal interrupt directly,
 145        * lpDosTask->current might be cleared (and event freed) in this very call! */
 146       DOSVM_SimulateInt((event->irq<8)?(event->irq+8):(event->irq-8+0x70),context,lpDosTask);
 147     } else {
 148       /* callback event */
 149       TRACE_(int)("dispatching callback event\n");
 150       (*event->relay)(lpDosTask,context,event->data);
 151       free(event);
 152     }
 153   }
 154   if (!SHOULD_PEND(lpDosTask->pending)) {
 155     TRACE_(int)("clearing Pending flag\n");
 156     CLR_PEND(context);
 157   }
 158 }
 159
 160 static void DOSVM_SendQueuedEvents(PCONTEXT context, LPDOSTASK lpDosTask)
 161 {
 162   /* we will send all queued events as long as interrupts are enabled,
 163    * but IRQ events will disable interrupts again */
 164   while (IS_PEND(context) && IF_ENABLED(context))
 165     DOSVM_SendQueuedEvent(context,lpDosTask);
 166 }
 167
 168 void DOSVM_QueueEvent( int irq, int priority, void (*relay)(LPDOSTASK,PCONTEXT,void*), void *data)
 169 {
 170   LPDOSTASK lpDosTask = MZ_Current();
 171   LPDOSEVENT event, cur, prev;
 172
 173   if (lpDosTask) {
 174     event = malloc(sizeof(DOSEVENT));
 175     if (!event) {
 176       ERR_(int)("out of memory allocating event entry\n");
 177       return;
 178     }
 179     event->irq = irq; event->priority = priority;
 180     event->relay = relay; event->data = data;
 181
 182     /* insert event into linked list, in order *after*
 183      * all earlier events of higher or equal priority */
 184     cur = lpDosTask->pending; prev = NULL;
 185     while (cur && cur->priority<=priority) {
 186       prev = cur;
 187       cur = cur->next;
 188     }
 189     event->next = cur;
 190     if (prev) prev->next = event;
 191     else lpDosTask->pending = event;
 192
 193     /* get dosmod's attention to the new event, except for irq==0 where we already have it */
 194     if (irq && !lpDosTask->sig_sent) {
 195       TRACE_(int)("new event queued, signalling dosmod\n");
 196       kill(lpDosTask->task,SIGUSR2);
 197       lpDosTask->sig_sent++;
 198     } else {
 199       TRACE_(int)("new event queued\n");
 200     }
 201   }
 202 }
 203
 204 #define CV CP(eax,EAX); CP(ecx,ECX); CP(edx,EDX); CP(ebx,EBX); \
 205            CP(esi,ESI); CP(edi,EDI); CP(esp,ESP); CP(ebp,EBP); \
 206            CP(cs,CS); CP(ds,DS); CP(es,ES); \
 207            CP(ss,SS); CP(fs,FS); CP(gs,GS); \
 208            CP(eip,EIP); CP(eflags,EFL)
 209
 210 static int DOSVM_Process( LPDOSTASK lpDosTask, int fn, int sig,
 211                           struct vm86plus_struct*VM86 )
 212 {
 213  SIGCONTEXT sigcontext;
 214  CONTEXT context;
 215  int ret=0;
 216
 217  if (VM86_TYPE(fn)==VM86_UNKNOWN) {
 218   /* INSTR_EmulateInstruction needs a SIGCONTEXT, not a CONTEXT... */
 219 #define CP(x,y) y##_sig(&sigcontext) = VM86->regs.x
 220   CV;
 221 #undef CP
 222   if (fnINSTR_EmulateInstruction) ret=fnINSTR_EmulateInstruction(&sigcontext);
 223   else ERR_(module)("fnINSTR_EmulateInstruction is not initialized!\n");
 224 #define CP(x,y) VM86->regs.x = y##_sig(&sigcontext)
 225   CV;
 226 #undef CP
 227   if (ret) return 0;
 228   ret=0;
 229  }
 230 #define CP(x,y) y##_reg(&context) = VM86->regs.x
 231  CV;
 232 #undef CP
 233  (void*)V86BASE(&context)=lpDosTask->img;
 234 #ifdef TRY_PICRETURN
 235  if (VM86->vm86plus.force_return_for_pic) {
 236    SET_PEND(&context);
 237  }
 238 #else
 239  /* linux doesn't preserve pending flag on return */
 240  if (SHOULD_PEND(lpDosTask->pending)) {
 241    SET_PEND(&context);
 242  }
 243 #endif
 244
 245  switch (VM86_TYPE(fn)) {
 246   case VM86_SIGNAL:
 247    TRACE_(int)("DOS module caught signal %d\n",sig);
 248    if ((sig==SIGALRM) || (sig==SIGUSR2)) {
 249      if (sig==SIGALRM) {
 250        DOSVM_QueueEvent(0,DOS_PRIORITY_REALTIME,NULL,NULL);
 251      }
 252      if (lpDosTask->pending) {
 253        TRACE_(int)("setting Pending flag, interrupts are currently %s\n",
 254                  IF_ENABLED(&context) ? "enabled" : "disabled");
 255        SET_PEND(&context);
 256        DOSVM_SendQueuedEvents(&context,lpDosTask);
 257      } else {
 258        TRACE_(int)("no events are pending, clearing Pending flag\n");
 259        CLR_PEND(&context);
 260      }
 261      if (sig==SIGUSR2) lpDosTask->sig_sent--;
 262    } else
 263    if (sig==SIGHUP) {
 264     if (ctx_debug_call) ctx_debug_call(SIGTRAP,&context);
 265    } else
 266    if ((sig==SIGILL)||(sig==SIGSEGV)) {
 267     if (ctx_debug_call) ctx_debug_call(SIGILL,&context);
 268    } else {
 269     DOSVM_Dump(lpDosTask,fn,sig,VM86);
 270     ret=-1;
 271    }
 272    break;
 273   case VM86_UNKNOWN: /* unhandled GPF */
 274    DOSVM_Dump(lpDosTask,fn,sig,VM86);
 275    if (ctx_debug_call) ctx_debug_call(SIGSEGV,&context); else ret=-1;
 276    break;
 277   case VM86_INTx:
 278    if (TRACE_ON(relay))
 279     DPRINTF("Call DOS int 0x%02x (EAX=%08lx) ret=%04lx:%04lx\n",VM86_ARG(fn),context.Eax,context.SegCs,context.Eip);
 280    ret=DOSVM_Int(VM86_ARG(fn),&context,lpDosTask);
 281    if (TRACE_ON(relay))
 282     DPRINTF("Ret  DOS int 0x%02x (EAX=%08lx) ret=%04lx:%04lx\n",VM86_ARG(fn),context.Eax,context.SegCs,context.Eip);
 283    break;
 284   case VM86_STI:
 285   case VM86_PICRETURN:
 286     TRACE_(int)("DOS task enabled interrupts with events pending, sending events\n");
 287     DOSVM_SendQueuedEvents(&context,lpDosTask);
 288     break;
 289   case VM86_TRAP:
 290    if (ctx_debug_call) ctx_debug_call(SIGTRAP,&context);
 291    break;
 292   default:
 293    DOSVM_Dump(lpDosTask,fn,sig,VM86);
 294    ret=-1;
 295  }
 296
 297 #define CP(x,y) VM86->regs.x = y##_reg(&context)
 298  CV;
 299 #undef CP
 300 #ifdef TRY_PICRETURN
 301  VM86->vm86plus.force_return_for_pic = IS_PEND(&context) ? 1 : 0;
 302  CLR_PEND(&context);
 303 #endif
 304  return ret;
 305 }
 306
 307 void DOSVM_ProcessMessage(LPDOSTASK lpDosTask,MSG *msg)
 308 {
 309   BYTE scan = 0;
 310
 311   fprintf(stderr,"got message %04x, wparam=%08x, lparam=%08lx\n",msg->message,msg->wParam,msg->lParam);
 312   if ((msg->message>=WM_MOUSEFIRST)&&
 313       (msg->message<=WM_MOUSELAST)) {
 314     INT_Int33Message(msg->message,msg->wParam,msg->lParam);
 315   } else {
 316     switch (msg->message) {
 317     case WM_KEYUP:
 318       scan = 0x80;
 319     case WM_KEYDOWN:
 320       scan |= (msg->lParam >> 16) & 0x7f;
 321
 322       /* check whether extended bit is set,
 323        * and if so, queue the extension prefix */
 324       if (msg->lParam & 0x1000000) {
 325         /* FIXME: some keys (function keys) have
 326          * extended bit set even when they shouldn't,
 327          * should check for them */
 328         INT_Int09SendScan(0xE0);
 329       }
 330       INT_Int09SendScan(scan);
 331       break;
 332     }
 333   }
 334 }
 335
 336 void DOSVM_Wait( int read_pipe, HANDLE hObject )
 337 {
 338   LPDOSTASK lpDosTask = MZ_Current();
 339   MSG msg;
 340   DWORD waitret;
 341   BOOL got_msg = FALSE;
 342
 343   do {
 344     /* check for messages (waste time before the response check below) */
 345     while (PeekMessageA(&msg,0,0,0,PM_REMOVE|PM_NOYIELD)) {
 346       /* got a message */
 347       DOSVM_ProcessMessage(lpDosTask,&msg);
 348       /* we don't need a TranslateMessage here */
 349       DispatchMessageA(&msg);
 350       got_msg = TRUE;
 351     }
 352     if (read_pipe == -1) {
 353       if (got_msg) break;
 354     } else {
 355       fd_set readfds;
 356       struct timeval timeout={0,0};
 357       /* quick check for response from dosmod
 358        * (faster than doing the full blocking wait, if data already available) */
 359       FD_ZERO(&readfds); FD_SET(read_pipe,&readfds);
 360       if (select(read_pipe+1,&readfds,NULL,NULL,&timeout)>0)
 361         break;
 362     }
 363     /* check for data from win32 console device */
 364
 365     /* nothing yet, block while waiting for something to do */
 366     waitret=MsgWaitForMultipleObjects(1,&hObject,FALSE,INFINITE,QS_ALLINPUT);
 367     if (waitret==(DWORD)-1) {
 368       ERR_(module)("dosvm wait error=%ld\n",GetLastError());
 369     }
 370     if (read_pipe != -1) {
 371       if (waitret==WAIT_OBJECT_0) break;
 372     }
 373   } while (TRUE);
 374 }
 375
 376 int DOSVM_Enter( PCONTEXT context )
 377 {
 378  LPDOSTASK lpDosTask = MZ_Current();
 379  struct vm86plus_struct VM86;
 380  int stat,len,sig;
 381
 382  if (!lpDosTask) {
 383   /* MZ_CreateProcess or MZ_AllocDPMITask should have been called first */
 384   ERR_(module)("dosmod has not been initialized!");
 385   return -1;
 386  }
 387
 388  if (context) {
 389 #define CP(x,y) VM86.regs.x = y##_reg(context)
 390   CV;
 391 #undef CP
 392   if (VM86.regs.eflags & IF_MASK)
 393     VM86.regs.eflags |= VIF_MASK;
 394  } else {
 395 /* initial setup */
 396   /* allocate standard DOS handles */
 397   FILE_InitProcessDosHandles();
 398   /* registers */
 399   memset(&VM86,0,sizeof(VM86));
 400   VM86.regs.cs=lpDosTask->init_cs;
 401   VM86.regs.eip=lpDosTask->init_ip;
 402   VM86.regs.ss=lpDosTask->init_ss;
 403   VM86.regs.esp=lpDosTask->init_sp;
 404   VM86.regs.ds=lpDosTask->psp_seg;
 405   VM86.regs.es=lpDosTask->psp_seg;
 406   VM86.regs.eflags=VIF_MASK;
 407   /* hmm, what else do we need? */
 408  }
 409
 410  /* main exchange loop */
 411  do {
 412   stat = VM86_ENTER;
 413   errno = 0;
 414   /* transmit VM86 structure to dosmod task */
 415   if (write(lpDosTask->write_pipe,&stat,sizeof(stat))!=sizeof(stat)) {
 416    ERR_(module)("dosmod sync lost, errno=%d, fd=%d, pid=%d\n",errno,lpDosTask->write_pipe,getpid());
 417    return -1;
 418   }
 419   if (write(lpDosTask->write_pipe,&VM86,sizeof(VM86))!=sizeof(VM86)) {
 420    ERR_(module)("dosmod sync lost, errno=%d\n",errno);
 421    return -1;
 422   }
 423   /* wait for response, doing other things in the meantime */
 424   DOSVM_Wait(lpDosTask->read_pipe, lpDosTask->hReadPipe);
 425   /* read response */
 426   while (1) {
 427     if ((len=read(lpDosTask->read_pipe,&stat,sizeof(stat)))==sizeof(stat)) break;
 428     if (((errno==EINTR)||(errno==EAGAIN))&&(len<=0)) {
 429      WARN_(module)("rereading dosmod return code due to errno=%d, result=%d\n",errno,len);
 430      continue;
 431     }
 432     ERR_(module)("dosmod sync lost reading return code, errno=%d, result=%d\n",errno,len);
 433     return -1;
 434   }
 435   TRACE_(module)("dosmod return code=%d\n",stat);
 436   while (1) {
 437     if ((len=read(lpDosTask->read_pipe,&VM86,sizeof(VM86)))==sizeof(VM86)) break;
 438     if (((errno==EINTR)||(errno==EAGAIN))&&(len<=0)) {
 439      WARN_(module)("rereading dosmod VM86 structure due to errno=%d, result=%d\n",errno,len);
 440      continue;
 441     }
 442     ERR_(module)("dosmod sync lost reading VM86 structure, errno=%d, result=%d\n",errno,len);
 443     return -1;
 444   }
 445   if ((stat&0xff)==DOSMOD_SIGNAL) {
 446     while (1) {
 447       if ((len=read(lpDosTask->read_pipe,&sig,sizeof(sig)))==sizeof(sig)) break;
 448       if (((errno==EINTR)||(errno==EAGAIN))&&(len<=0)) {
 449         WARN_(module)("rereading dosmod signal due to errno=%d, result=%d\n",errno,len);
 450         continue;
 451       }
 452       ERR_(module)("dosmod sync lost reading signal, errno=%d, result=%d\n",errno,len);
 453       return -1;
 454     } while (0);
 455   } else sig=0;
 456   /* got response */
 457  } while (DOSVM_Process(lpDosTask,stat,sig,&VM86)>=0);
 458
 459  if (context) {
 460 #define CP(x,y) y##_reg(context) = VM86.regs.x
 461   CV;
 462 #undef CP
 463  }
 464  return 0;
 465 }
 466
 467 void DOSVM_PIC_ioport_out( WORD port, BYTE val)
 468 {
 469   LPDOSTASK lpDosTask = MZ_Current();
 470   LPDOSEVENT event;
 471
 472   if (lpDosTask) {
 473     if ((port==0x20) && (val==0x20)) {
 474       if (lpDosTask->current) {
 475         /* EOI (End Of Interrupt) */
 476         TRACE_(int)("received EOI for current IRQ, clearing\n");
 477         event = lpDosTask->current;
 478         lpDosTask->current = event->next;
 479         if (event->relay)
 480         (*event->relay)(lpDosTask,NULL,event->data);
 481         free(event);
 482
 483         if (lpDosTask->pending &&
 484             !lpDosTask->sig_sent) {
 485           /* another event is pending, which we should probably
 486            * be able to process now, so tell dosmod about it */
 487           TRACE_(int)("another event pending, signalling dosmod\n");
 488           kill(lpDosTask->task,SIGUSR2);
 489           lpDosTask->sig_sent++;
 490         }
 491       } else {
 492         WARN_(int)("EOI without active IRQ\n");
 493       }
 494     } else {
 495       FIXME_(int)("unrecognized PIC command %02x\n",val);
 496     }
 497   }
 498 }
 499
 500 void DOSVM_SetTimer( unsigned ticks )
 501 {
 502   LPDOSTASK lpDosTask = MZ_Current();
 503   int stat=DOSMOD_SET_TIMER;
 504   struct timeval tim;
 505
 506   if (lpDosTask) {
 507     /* the PC clocks ticks at 1193180 Hz */
 508     tim.tv_sec=0;
 509     tim.tv_usec=((unsigned long long)ticks*1000000)/1193180;
 510     /* sanity check */
 511     if (!tim.tv_usec) tim.tv_usec=1;
 512
 513     if (write(lpDosTask->write_pipe,&stat,sizeof(stat))!=sizeof(stat)) {
 514       ERR_(module)("dosmod sync lost, errno=%d\n",errno);
 515       return;
 516     }
 517     if (write(lpDosTask->write_pipe,&tim,sizeof(tim))!=sizeof(tim)) {
 518       ERR_(module)("dosmod sync lost, errno=%d\n",errno);
 519       return;
 520     }
 521     /* there's no return */
 522   }
 523 }
 524
 525 unsigned DOSVM_GetTimer( void )
 526 {
 527   LPDOSTASK lpDosTask = MZ_Current();
 528   int stat=DOSMOD_GET_TIMER;
 529   struct timeval tim;
 530
 531   if (lpDosTask) {
 532     if (write(lpDosTask->write_pipe,&stat,sizeof(stat))!=sizeof(stat)) {
 533       ERR_(module)("dosmod sync lost, errno=%d\n",errno);
 534       return 0;
 535     }
 536     /* read response */
 537     while (1) {
 538       if (read(lpDosTask->read_pipe,&tim,sizeof(tim))==sizeof(tim)) break;
 539       if ((errno==EINTR)||(errno==EAGAIN)) continue;
 540       ERR_(module)("dosmod sync lost, errno=%d\n",errno);
 541       return 0;
 542     }
 543     return ((unsigned long long)tim.tv_usec*1193180)/1000000;
 544   }
 545   return 0;
 546 }
 547
 548 void DOSVM_SetSystemData( int id, void *data )
 549 {
 550   LPDOSTASK lpDosTask = MZ_Current();
 551   DOSSYSTEM *sys, *prev;
 552
 553   if (lpDosTask) {
 554     sys = lpDosTask->sys;
 555     prev = NULL;
 556     while (sys && (sys->id != id)) {
 557       prev = sys;
 558       sys = sys->next;
 559     }
 560     if (sys) {
 561       free(sys->data);
 562       sys->data = data;
 563     } else {
 564       sys = malloc(sizeof(DOSSYSTEM));
 565       sys->id = id;
 566       sys->data = data;
 567       sys->next = NULL;
 568       if (prev) prev->next = sys;
 569       else lpDosTask->sys = sys;
 570     }
 571   } else free(data);
 572 }
 573
 574 void* DOSVM_GetSystemData( int id )
 575 {
 576   LPDOSTASK lpDosTask = MZ_Current();
 577   DOSSYSTEM *sys;
 578
 579   if (lpDosTask) {
 580     sys = lpDosTask->sys;
 581     while (sys && (sys->id != id))
 582       sys = sys->next;
 583     if (sys)
 584       return sys->data;
 585   }
 586   return NULL;
 587 }
 588
 589 #else /* !MZ_SUPPORTED */
 590
 591 int DOSVM_Enter( PCONTEXT context )
 592 {
 593  ERR_(module)("DOS realmode not supported on this architecture!\n");
 594  return -1;
 595 }
 596
 597 void DOSVM_Wait( int read_pipe, HANDLE hObject) {}
 598 void DOSVM_PIC_ioport_out( WORD port, BYTE val) {}
 599 void DOSVM_SetTimer( unsigned ticks ) {}
 600 unsigned DOSVM_GetTimer( void ) { return 0; }
 601 void DOSVM_SetSystemData( int id, void *data ) { free(data); }
 602 void* DOSVM_GetSystemData( int id ) { return NULL; }
 603 void DOSVM_QueueEvent( int irq, int priority, void (*relay)(LPDOSTASK,PCONTEXT,void*), void *data) {}
 604
 605 #endif