/*
 * Task functions
 *
 * Copyright 1995 Alexandre Julliard
 */

#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <unistd.h>

#include "wine/winbase16.h"
#include "user.h"
#include "callback.h"
#include "drive.h"
#include "file.h"
#include "global.h"
#include "instance.h"
#include "message.h"
#include "miscemu.h"
#include "module.h"
#include "neexe.h"
#include "peexe.h"
#include "pe_image.h"
#include "process.h"
#include "queue.h"
#include "selectors.h"
#include "stackframe.h"
#include "task.h"
#include "thread.h"
#include "toolhelp.h"
#include "winnt.h"
#include "winsock.h"
#include "thread.h"
#include "syslevel.h"
#include "debug.h"
#include "dosexe.h"
#include "dde_proc.h"
#include "server.h"

DECLARE_DEBUG_CHANNEL(relay)
DECLARE_DEBUG_CHANNEL(task)
DECLARE_DEBUG_CHANNEL(toolhelp)

  /* Min. number of thunks allocated when creating a new segment */
#define MIN_THUNKS  32

  /* Pointer to function to switch to a larger stack */
int (*IF1632_CallLargeStack)( int (*func)(), void *arg ) = NULL;

  /* Pointer to debugger callback routine */
void (*TASK_AddTaskEntryBreakpoint)( HTASK16 hTask ) = NULL;

static THHOOK DefaultThhook = { 0 };
THHOOK *pThhook = &DefaultThhook;

#define hCurrentTask (pThhook->CurTDB)
#define hFirstTask   (pThhook->HeadTDB)
#define hLockedTask  (pThhook->LockTDB)

static HTASK16 hTaskToKill = 0;
static UINT16 nTaskCount = 0;

static void TASK_YieldToSystem( void );

extern BOOL THREAD_InitDone;


/***********************************************************************
 *	     TASK_InstallTHHook
 */
void TASK_InstallTHHook( THHOOK *pNewThhook )
{
     THHOOK *pOldThhook = pThhook;

     pThhook = pNewThhook? pNewThhook : &DefaultThhook;

     *pThhook = *pOldThhook;
}

/***********************************************************************
 *	     TASK_GetNextTask
 */
HTASK16 TASK_GetNextTask( HTASK16 hTask )
{
    TDB* pTask = (TDB*)GlobalLock16(hTask);

    if (pTask->hNext) return pTask->hNext;
    return (hFirstTask != hTask) ? hFirstTask : 0; 
}

/***********************************************************************
 *           TASK_LinkTask
 */
static void TASK_LinkTask( HTASK16 hTask )
{
    HTASK16 *prevTask;
    TDB *pTask;

    if (!(pTask = (TDB *)GlobalLock16( hTask ))) return;
    prevTask = &hFirstTask;
    while (*prevTask)
    {
        TDB *prevTaskPtr = (TDB *)GlobalLock16( *prevTask );
        if (prevTaskPtr->priority >= pTask->priority) break;
        prevTask = &prevTaskPtr->hNext;
    }
    pTask->hNext = *prevTask;
    *prevTask = hTask;
    nTaskCount++;
}


/***********************************************************************
 *           TASK_UnlinkTask
 */
static void TASK_UnlinkTask( HTASK16 hTask )
{
    HTASK16 *prevTask;
    TDB *pTask;

    prevTask = &hFirstTask;
    while (*prevTask && (*prevTask != hTask))
    {
        pTask = (TDB *)GlobalLock16( *prevTask );
        prevTask = &pTask->hNext;
    }
    if (*prevTask)
    {
        pTask = (TDB *)GlobalLock16( *prevTask );
        *prevTask = pTask->hNext;
        pTask->hNext = 0;
        nTaskCount--;
    }
}


/***********************************************************************
 *           TASK_CreateThunks
 *
 * Create a thunk free-list in segment 'handle', starting from offset 'offset'
 * and containing 'count' entries.
 */
static void TASK_CreateThunks( HGLOBAL16 handle, WORD offset, WORD count )
{
    int i;
    WORD free;
    THUNKS *pThunk;

    pThunk = (THUNKS *)((BYTE *)GlobalLock16( handle ) + offset);
    pThunk->next = 0;
    pThunk->magic = THUNK_MAGIC;
    pThunk->free = (int)&pThunk->thunks - (int)pThunk;
    free = pThunk->free;
    for (i = 0; i < count-1; i++)
    {
        free += 8;  /* Offset of next thunk */
        pThunk->thunks[4*i] = free;
    }
    pThunk->thunks[4*i] = 0;  /* Last thunk */
}


/***********************************************************************
 *           TASK_AllocThunk
 *
 * Allocate a thunk for MakeProcInstance().
 */
static SEGPTR TASK_AllocThunk( HTASK16 hTask )
{
    TDB *pTask;
    THUNKS *pThunk;
    WORD sel, base;
    
    if (!(pTask = (TDB *)GlobalLock16( hTask ))) return 0;
    sel = pTask->hCSAlias;
    pThunk = &pTask->thunks;
    base = (int)pThunk - (int)pTask;
    while (!pThunk->free)
    {
        sel = pThunk->next;
        if (!sel)  /* Allocate a new segment */
        {
            sel = GLOBAL_Alloc( GMEM_FIXED, sizeof(THUNKS) + (MIN_THUNKS-1)*8,
                                pTask->hPDB, TRUE, FALSE, FALSE );
            if (!sel) return (SEGPTR)0;
            TASK_CreateThunks( sel, 0, MIN_THUNKS );
            pThunk->next = sel;
        }
        pThunk = (THUNKS *)GlobalLock16( sel );
        base = 0;
    }
    base += pThunk->free;
    pThunk->free = *(WORD *)((BYTE *)pThunk + pThunk->free);
    return PTR_SEG_OFF_TO_SEGPTR( sel, base );
}


/***********************************************************************
 *           TASK_FreeThunk
 *
 * Free a MakeProcInstance() thunk.
 */
static BOOL TASK_FreeThunk( HTASK16 hTask, SEGPTR thunk )
{
    TDB *pTask;
    THUNKS *pThunk;
    WORD sel, base;
    
    if (!(pTask = (TDB *)GlobalLock16( hTask ))) return 0;
    sel = pTask->hCSAlias;
    pThunk = &pTask->thunks;
    base = (int)pThunk - (int)pTask;
    while (sel && (sel != HIWORD(thunk)))
    {
        sel = pThunk->next;
        pThunk = (THUNKS *)GlobalLock16( sel );
        base = 0;
    }
    if (!sel) return FALSE;
    *(WORD *)((BYTE *)pThunk + LOWORD(thunk) - base) = pThunk->free;
    pThunk->free = LOWORD(thunk) - base;
    return TRUE;
}


/***********************************************************************
 *           TASK_CallToStart
 *
 * 32-bit entry point for a new task. This function is responsible for
 * setting up the registers and jumping to the 16-bit entry point.
 */
static void TASK_CallToStart(void)
{
    TDB *pTask = (TDB *)GlobalLock16( GetCurrentTask() );
    NE_MODULE *pModule = NE_GetPtr( pTask->hModule );
    SEGTABLEENTRY *pSegTable = NE_SEG_TABLE( pModule );

    SET_CUR_THREAD( pTask->thdb );
    CLIENT_InitThread();

    /* Terminate the stack frame chain */
    memset(THREAD_STACK16( pTask->thdb ), '\0', sizeof(STACK16FRAME));

    /* Call USER signal proc */
    PROCESS_CallUserSignalProc( USIG_THREAD_INIT, 0, 0 );  /* for initial thread */
    PROCESS_CallUserSignalProc( USIG_PROCESS_INIT, 0, 0 );
    PROCESS_CallUserSignalProc( USIG_PROCESS_LOADED, 0, 0 );
    PROCESS_CallUserSignalProc( USIG_PROCESS_RUNNING, 0, 0 );

    if (pModule->flags & NE_FFLAGS_WIN32)
    {
        ERR( task, "Called for Win32 task!\n" );
        ExitProcess( 1 );
    }
    else if (pModule->dos_image)
    {
        DOSVM_Enter( NULL );
        ExitProcess( 0 );
    }
    else
    {
        /* Registers at initialization must be:
         * ax   zero
         * bx   stack size in bytes
         * cx   heap size in bytes
         * si   previous app instance
         * di   current app instance
         * bp   zero
         * es   selector to the PSP
         * ds   dgroup of the application
         * ss   stack selector
         * sp   top of the stack
         */
        CONTEXT context;

        memset( &context, 0, sizeof(context) );
        CS_reg(&context)  = GlobalHandleToSel16(pSegTable[pModule->cs - 1].hSeg);
        DS_reg(&context)  = GlobalHandleToSel16(pSegTable[pModule->dgroup - 1].hSeg);
        ES_reg(&context)  = pTask->hPDB;
        EIP_reg(&context) = pModule->ip;
        EBX_reg(&context) = pModule->stack_size;
        ECX_reg(&context) = pModule->heap_size;
        EDI_reg(&context) = context.SegDs;

        TRACE(task, "Starting main program: cs:ip=%04lx:%04x ds=%04lx ss:sp=%04x:%04x\n",
                      CS_reg(&context), IP_reg(&context), DS_reg(&context),
                      SELECTOROF(pTask->thdb->cur_stack),
                      OFFSETOF(pTask->thdb->cur_stack) );

        Callbacks->CallRegisterShortProc( &context, 0 );
        /* This should never return */
        ERR( task, "Main program returned! (should never happen)\n" );
        ExitProcess( 1 );
    }
}


/***********************************************************************
 *           TASK_Create
 *
 * NOTE: This routine might be called by a Win32 thread. We don't have
 *       any real problems with that, since we operated merely on a private
 *       TDB structure that is not yet linked into the task list.
 */
BOOL TASK_Create( THDB *thdb, NE_MODULE *pModule, HINSTANCE16 hInstance,
                  HINSTANCE16 hPrevInstance, UINT16 cmdShow)
{
    HTASK16 hTask;
    TDB *pTask;
    LPSTR cmd_line;
    WORD sp;
    char *stack32Top;
    char name[10];
    STACK16FRAME *frame16;
    STACK32FRAME *frame32;
    PDB *pdb32 = thdb->process;
    SEGTABLEENTRY *pSegTable = NE_SEG_TABLE( pModule );

      /* Allocate the task structure */

    hTask = GLOBAL_Alloc( GMEM_FIXED | GMEM_ZEROINIT, sizeof(TDB),
                          pModule->self, FALSE, FALSE, FALSE );
    if (!hTask) return FALSE;
    pTask = (TDB *)GlobalLock16( hTask );

    /* Fill the task structure */

    pTask->nEvents       = 0;
    pTask->hSelf         = hTask;
    pTask->flags         = 0;

    if (pModule->flags & NE_FFLAGS_WIN32)
    	pTask->flags 	|= TDBF_WIN32;
    if (pModule->lpDosTask)
    	pTask->flags 	|= TDBF_WINOLDAP;

    pTask->version       = pModule->expected_version;
    pTask->hInstance     = hInstance? hInstance : pModule->self;
    pTask->hPrevInstance = hPrevInstance;
    pTask->hModule       = pModule->self;
    pTask->hParent       = GetCurrentTask();
    pTask->magic         = TDB_MAGIC;
    pTask->nCmdShow      = cmdShow;
    pTask->thdb          = thdb;
    pTask->curdrive      = DRIVE_GetCurrentDrive() | 0x80;
    strcpy( pTask->curdir, "\\" );
    lstrcpynA( pTask->curdir + 1, DRIVE_GetDosCwd( DRIVE_GetCurrentDrive() ),
                 sizeof(pTask->curdir) - 1 );

      /* Create the thunks block */

    TASK_CreateThunks( hTask, (int)&pTask->thunks - (int)pTask, 7 );

      /* Copy the module name */

    GetModuleName16( pModule->self, name, sizeof(name) );
    strncpy( pTask->module_name, name, sizeof(pTask->module_name) );

      /* Allocate a selector for the PDB */

    pTask->hPDB = GLOBAL_CreateBlock( GMEM_FIXED, &pTask->pdb, sizeof(PDB16),
                                    pModule->self, FALSE, FALSE, FALSE, NULL );

      /* Fill the PDB */

    pTask->pdb.int20 = 0x20cd;
    pTask->pdb.dispatcher[0] = 0x9a;  /* ljmp */
    PUT_DWORD(&pTask->pdb.dispatcher[1], (DWORD)NE_GetEntryPoint(
           GetModuleHandle16("KERNEL"), 102 ));  /* KERNEL.102 is DOS3Call() */
    pTask->pdb.savedint22 = INT_GetPMHandler( 0x22 );
    pTask->pdb.savedint23 = INT_GetPMHandler( 0x23 );
    pTask->pdb.savedint24 = INT_GetPMHandler( 0x24 );
    pTask->pdb.fileHandlesPtr =
        PTR_SEG_OFF_TO_SEGPTR( GlobalHandleToSel16(pTask->hPDB),
                               (int)&((PDB16 *)0)->fileHandles );
    pTask->pdb.hFileHandles = 0;
    memset( pTask->pdb.fileHandles, 0xff, sizeof(pTask->pdb.fileHandles) );
    pTask->pdb.environment    = pdb32->env_db->env_sel;
    pTask->pdb.nbFiles        = 20;

    /* Fill the command line */

    cmd_line = pdb32->env_db->cmd_line;
    while (*cmd_line && (*cmd_line != ' ') && (*cmd_line != '\t')) cmd_line++;
    while ((*cmd_line == ' ') || (*cmd_line == '\t')) cmd_line++;
    lstrcpynA( pTask->pdb.cmdLine+1, cmd_line, sizeof(pTask->pdb.cmdLine)-1);
    pTask->pdb.cmdLine[0] = strlen( pTask->pdb.cmdLine + 1 );

      /* Get the compatibility flags */

    pTask->compat_flags = GetProfileIntA( "Compatibility", name, 0 );

      /* Allocate a code segment alias for the TDB */

    pTask->hCSAlias = GLOBAL_CreateBlock( GMEM_FIXED, (void *)pTask,
                                          sizeof(TDB), pTask->hPDB, TRUE,
                                          FALSE, FALSE, NULL );

      /* Set the owner of the environment block */

    FarSetOwner16( pTask->pdb.environment, pTask->hPDB );

      /* Default DTA overwrites command-line */

    pTask->dta = PTR_SEG_OFF_TO_SEGPTR( pTask->hPDB, 
                                (int)&pTask->pdb.cmdLine - (int)&pTask->pdb );

    /* If we have a DGROUP/hInstance, use it for 16-bit stack */
 
    if ( hInstance )
    {
        if (!(sp = pModule->sp))
            sp = pSegTable[pModule->ss-1].minsize + pModule->stack_size;
        sp &= ~1;  sp -= sizeof(STACK16FRAME);
        pTask->thdb->cur_stack = PTR_SEG_OFF_TO_SEGPTR( hInstance, sp );
    }

    /* Create the 16-bit stack frame */

    pTask->thdb->cur_stack -= sizeof(STACK16FRAME);
    frame16 = (STACK16FRAME *)PTR_SEG_TO_LIN( pTask->thdb->cur_stack );
    frame16->ebp = OFFSETOF( pTask->thdb->cur_stack ) + (int)&((STACK16FRAME *)0)->bp;
    frame16->bp = LOWORD(frame16->ebp);
    frame16->ds = frame16->es = hInstance;
    frame16->fs = 0;
    frame16->entry_point = 0;
    frame16->entry_cs = 0;
    frame16->mutex_count = 1; /* TASK_Reschedule is called from 16-bit code */
    /* The remaining fields will be initialized in TASK_Reschedule */

    /* Create the 32-bit stack frame */

    stack32Top = (char*)pTask->thdb->teb.stack_top;
    frame16->frame32 = frame32 = (STACK32FRAME *)stack32Top - 1;
    frame32->frame16 = pTask->thdb->cur_stack + sizeof(STACK16FRAME);
    frame32->edi     = 0;
    frame32->esi     = 0;
    frame32->edx     = 0;
    frame32->ecx     = 0;
    frame32->ebx     = 0;
    frame32->retaddr = (DWORD)TASK_CallToStart;
    /* The remaining fields will be initialized in TASK_Reschedule */

    /* Enter task handle into thread and process */
 
    pTask->thdb->teb.htask16 = pTask->thdb->process->task = hTask;
 
    TRACE(task, "module='%s' cmdline='%s' task=%04x\n",
          name, cmd_line, hTask );

    return TRUE;
}

/***********************************************************************
 *           TASK_StartTask
 *
 * NOTE: This routine might be called by a Win32 thread. Thus, we need
 *       to be careful to protect global data structures. We do this
 *       by entering the Win16Lock while linking the task into the
 *       global task list.
 */
void TASK_StartTask( HTASK16 hTask )
{
    TDB *pTask = (TDB *)GlobalLock16( hTask );
    if ( !pTask ) return;

    /* Add the task to the linked list */

    SYSLEVEL_EnterWin16Lock();
    TASK_LinkTask( hTask );
    SYSLEVEL_LeaveWin16Lock();

    TRACE(task, "linked task %04x\n", hTask );

    /* If requested, add entry point breakpoint */

    if ( TASK_AddTaskEntryBreakpoint )
        TASK_AddTaskEntryBreakpoint( hTask );

    /* Get the task up and running. */

    if ( THREAD_IsWin16( pTask->thdb ) )
    {
        pTask->nEvents++;

        /* If we ourselves are a 16-bit task, we simply Yield(). 
           If we are 32-bit however, we need to signal the scheduler. */

        if ( THREAD_IsWin16( THREAD_Current() ) )
            OldYield16();
        else
            EVENT_WakeUp();
    }
    else
    {
        /* To start a 32-bit task, we spawn its initial thread. */

        SYSDEPS_SpawnThread( pTask->thdb );
    }
}


/***********************************************************************
 *           TASK_DeleteTask
 */
static void TASK_DeleteTask( HTASK16 hTask )
{
    TDB *pTask;
    HGLOBAL16 hPDB;

    if (!(pTask = (TDB *)GlobalLock16( hTask ))) return;
    hPDB = pTask->hPDB;

    pTask->magic = 0xdead; /* invalidate signature */

    /* Delete the Win32 part of the task */

/*    PROCESS_FreePDB( pTask->thdb->process ); FIXME */
/*    K32OBJ_DecCount( &pTask->thdb->header ); FIXME */

    /* Free the selector aliases */

    GLOBAL_FreeBlock( pTask->hCSAlias );
    GLOBAL_FreeBlock( pTask->hPDB );

    /* Free the task module */

    FreeModule16( pTask->hModule );

    /* Free the task structure itself */

    GlobalFree16( hTask );

    /* Free all memory used by this task (including the 32-bit stack, */
    /* the environment block and the thunk segments). */

    GlobalFreeAll16( hPDB );
}

/***********************************************************************
 *           TASK_KillTask
 */
void TASK_KillTask( HTASK16 hTask )
{
    TDB *pTask; 

    /* Enter the Win16Lock to protect global data structures */
    SYSLEVEL_EnterWin16Lock();

    if ( !hTask ) hTask = GetCurrentTask();
    pTask = (TDB *)GlobalLock16( hTask );
    if ( !pTask ) 
    {
        SYSLEVEL_LeaveWin16Lock();
        return;
    }

    TRACE(task, "Killing task %04x\n", hTask );

    /* Delete active sockets */

    if( pTask->pwsi )
	WINSOCK_DeleteTaskWSI( pTask, pTask->pwsi );

#ifdef MZ_SUPPORTED
{
    /* Kill DOS VM task */
    NE_MODULE *pModule = NE_GetPtr( pTask->hModule );
    if ( pModule->lpDosTask )
        MZ_KillModule( pModule->lpDosTask );
}
#endif

    /* Perform USER cleanup */

    if (pTask->userhandler)
        pTask->userhandler( hTask, USIG16_TERMINATION, 0,
                            pTask->hInstance, pTask->hQueue );

    PROCESS_CallUserSignalProc( USIG_PROCESS_EXIT, 0, 0 );
    PROCESS_CallUserSignalProc( USIG_THREAD_EXIT, 0, 0 );     /* FIXME */
    PROCESS_CallUserSignalProc( USIG_PROCESS_DESTROY, 0, 0 );

    if (nTaskCount <= 1)
    {
        TRACE(task, "this is the last task, exiting\n" );
        USER_ExitWindows();
    }

    /* FIXME: Hack! Send a message to the initial task so that
     * the GetMessage wakes up and the initial task can check whether
     * it is the only remaining one and terminate itself ...
     * The initial task should probably install hooks or something
     * to get informed about task termination :-/
     */
    Callout.PostAppMessage16( PROCESS_Initial()->task, WM_NULL, 0, 0 );

    /* Remove the task from the list to be sure we never switch back to it */
    TASK_UnlinkTask( hTask );
    if( nTaskCount )
    {
        TDB* p = (TDB *)GlobalLock16( hFirstTask );
        while( p )
        {
            if( p->hYieldTo == hTask ) p->hYieldTo = 0;
            p = (TDB *)GlobalLock16( p->hNext );
        }
    }

    pTask->nEvents = 0;

    if ( hLockedTask == hTask )
        hLockedTask = 0;

    if ( hTaskToKill && ( hTaskToKill != hCurrentTask ) )
    {
        /* If another task is already marked for destruction, */
        /* we can kill it now, as we are in another context.  */ 
        TASK_DeleteTask( hTaskToKill );
        hTaskToKill = 0;
    }

    /*
     * If hTask is not the task currently scheduled by the Win16
     * scheduler, we simply delete it; otherwise we mark it for
     * destruction.  Note that if the current task is a 32-bit
     * one, hCurrentTask is *different* from GetCurrentTask()!
     */
    if ( hTask == hCurrentTask )
    {
        assert( hTaskToKill == 0 || hTaskToKill == hCurrentTask );
        hTaskToKill = hCurrentTask;
    }
    else
        TASK_DeleteTask( hTask );

    SYSLEVEL_LeaveWin16Lock();
}

    
/***********************************************************************
 *           TASK_KillCurrentTask
 *
 * Kill the currently running task. As it's not possible to kill the
 * current task like this, it is simply marked for destruction, and will
 * be killed when either TASK_Reschedule or this function is called again 
 * in the context of another task.
 */
void TASK_KillCurrentTask( INT16 exitCode )
{
    if ( !THREAD_IsWin16( THREAD_Current() ) )
    {
        FIXME(task, "called for Win32 thread (%04x)!\n", THREAD_Current()->teb_sel);
        return;
    }

    assert(hCurrentTask == GetCurrentTask());

    TRACE(task, "Killing current task %04x\n", hCurrentTask );

    TASK_KillTask( 0 );

    TASK_YieldToSystem();

    /* We should never return from this Yield() */

    ERR(task,"Return of the living dead %04x!!!\n", hCurrentTask);
    exit(1);
}

/***********************************************************************
 *           TASK_Reschedule
 *
 * This is where all the magic of task-switching happens!
 *
 * Note: This function should only be called via the TASK_YieldToSystem()
 *       wrapper, to make sure that all the context is saved correctly.
 *   
 *       It must not call functions that may yield control.
 */
BOOL TASK_Reschedule(void)
{
    TDB *pOldTask = NULL, *pNewTask;
    HTASK16 hTask = 0;
    STACK16FRAME *newframe16;
    BOOL pending = FALSE;

    /* Get the initial task up and running */
    if (!hCurrentTask && GetCurrentTask())
    {
        /* We need to remove one pair of stackframes (exept for Winelib) */
        STACK16FRAME *oldframe16 = CURRENT_STACK16;
        STACK32FRAME *oldframe32 = oldframe16->frame32;
        STACK16FRAME *newframe16 = PTR_SEG_TO_LIN( oldframe32->frame16 );
        STACK32FRAME *newframe32 = newframe16->frame32;
        if (newframe32)
        {
            newframe16->entry_ip     = oldframe16->entry_ip;
            newframe16->entry_cs     = oldframe16->entry_cs;
            newframe16->ip           = oldframe16->ip;
            newframe16->cs           = oldframe16->cs;
            newframe32->ebp          = oldframe32->ebp;
            newframe32->restore_addr = oldframe32->restore_addr;
            newframe32->codeselector = oldframe32->codeselector;

            THREAD_Current()->cur_stack = oldframe32->frame16;
        }

        hCurrentTask = GetCurrentTask();
        pNewTask = (TDB *)GlobalLock16( hCurrentTask );
        pNewTask->ss_sp = pNewTask->thdb->cur_stack;
        return FALSE;
    }

    /* NOTE: As we are entered from 16-bit code, we hold the Win16Lock.
             We hang onto it thoughout most of this routine, so that accesses
             to global variables (most notably the task list) are protected. */
    assert(hCurrentTask == GetCurrentTask());

    TRACE(task, "entered with hTask %04x (pid %d)\n", hCurrentTask, getpid());

#ifdef CONFIG_IPC
    /* FIXME: What about the Win16Lock ??? */
    dde_reschedule();
#endif
      /* First check if there's a task to kill */

    if (hTaskToKill && (hTaskToKill != hCurrentTask))
    {
        TASK_DeleteTask( hTaskToKill );
        hTaskToKill = 0;
    }

    /* Find a task to yield to */

    pOldTask = (TDB *)GlobalLock16( hCurrentTask );
    if (pOldTask && pOldTask->hYieldTo)
    {
        /* check for DirectedYield() */

        hTask = pOldTask->hYieldTo;
        pNewTask = (TDB *)GlobalLock16( hTask );
        if( !pNewTask || !pNewTask->nEvents) hTask = 0;
        pOldTask->hYieldTo = 0;
    }

    /* extract hardware events only! */

    if (!hTask) pending = EVENT_WaitNetEvent( FALSE, TRUE );

    while (!hTask)
    {
        /* Find a task that has an event pending */

        hTask = hFirstTask;
        while (hTask)
        {
            pNewTask = (TDB *)GlobalLock16( hTask );

	    TRACE(task, "\ttask = %04x, events = %i\n", hTask, pNewTask->nEvents);

            if (pNewTask->nEvents) break;
            hTask = pNewTask->hNext;
        }
        if (hLockedTask && (hTask != hLockedTask)) hTask = 0;
        if (hTask) break;

        /* If a non-hardware event is pending, return to TASK_YieldToSystem
           temporarily to process it safely */
        if (pending) return TRUE;

        /* No task found, wait for some events to come in */

        /* NOTE: We release the Win16Lock while waiting for events. This is to enable
                 Win32 threads to thunk down to 16-bit temporarily. Since Win16
                 tasks won't execute and Win32 threads are not allowed to enter 
                 TASK_Reschedule anyway, there should be no re-entrancy problem ... */

        SYSLEVEL_ReleaseWin16Lock();
        pending = EVENT_WaitNetEvent( TRUE, TRUE );
        SYSLEVEL_RestoreWin16Lock();
    }

    if (hTask == hCurrentTask) 
    {
        /* Allow Win32 threads to thunk down even while a Win16 task is
           in a tight PeekMessage() or Yield() loop ... */
        SYSLEVEL_ReleaseWin16Lock();
        SYSLEVEL_RestoreWin16Lock();

        TRACE(task, "returning to the current task(%04x)\n", hTask );
        return FALSE;  /* Nothing to do */
    }
    pNewTask = (TDB *)GlobalLock16( hTask );
    TRACE(task, "Switching to task %04x (%.8s)\n",
                  hTask, pNewTask->module_name );

     /* Make the task the last in the linked list (round-robin scheduling) */

    pNewTask->priority++;
    TASK_UnlinkTask( hTask );
    TASK_LinkTask( hTask );
    pNewTask->priority--;

    /* Finish initializing the new task stack if necessary */

    newframe16 = THREAD_STACK16( pNewTask->thdb );
    if (!newframe16->entry_cs)
    {
        STACK16FRAME *oldframe16 = CURRENT_STACK16;
        STACK32FRAME *oldframe32 = oldframe16->frame32;
        STACK32FRAME *newframe32 = newframe16->frame32;
        newframe16->entry_ip     = oldframe16->entry_ip;
        newframe16->entry_cs     = oldframe16->entry_cs;
        newframe16->ip           = oldframe16->ip;
        newframe16->cs           = oldframe16->cs;
        newframe32->ebp          = oldframe32->ebp;
        newframe32->restore_addr = oldframe32->restore_addr;
        newframe32->codeselector = oldframe32->codeselector;
    }
    
    /* Switch to the new stack */

    /* NOTE: We need to release/restore the Win16Lock, as the task
             switched to might be at another recursion level than
             the old task ... */

    SYSLEVEL_ReleaseWin16Lock();

    hCurrentTask = hTask;
    SET_CUR_THREAD( pNewTask->thdb );
    pNewTask->ss_sp = pNewTask->thdb->cur_stack;

    SYSLEVEL_RestoreWin16Lock();

    return FALSE;
}


/***********************************************************************
 *           TASK_YieldToSystem
 *
 * Scheduler interface, this way we ensure that all "unsafe" events are
 * processed outside the scheduler.
 */
static void TASK_YieldToSystem( void )
{
    if ( !THREAD_IsWin16( THREAD_Current() ) )
    {
        FIXME(task, "called for Win32 thread (%04x)!\n", THREAD_Current()->teb_sel);
        return;
    }

    if ( Callbacks->CallTaskRescheduleProc() )
    {
        /* NOTE: We get here only when no task has an event. This means also
                 the current task, so we shouldn't actually return to the
                 caller here. But, we need to do so, as the EVENT_WaitNetEvent
                 call could lead to a complex series of inter-task SendMessage
                 calls which might leave this task in a state where it again
                 has no event, but where its queue's wakeMask is also reset
                 to zero. Reentering TASK_Reschedule in this state would be 
                 suicide.  Hence, we do return to the caller after processing
                 non-hardware events. Actually, this should not hurt anyone,
                 as the caller must be WaitEvent, and thus the QUEUE_WaitBits
                 loop in USER. Should there actually be no message pending 
                 for this task after processing non-hardware events, that loop
                 will simply return to WaitEvent.  */
                 
        EVENT_WaitNetEvent( FALSE, FALSE );
    }
}


/***********************************************************************
 *           InitTask  (KERNEL.91)
 *
 * Called by the application startup code.
 */
void WINAPI InitTask16( CONTEXT *context )
{
    TDB *pTask;
    NE_MODULE *pModule;
    SEGTABLEENTRY *pSegTable;
    INSTANCEDATA *pinstance;
    LONG stacklow, stackhi;

    if (context) EAX_reg(context) = 0;
    if (!(pTask = (TDB *)GlobalLock16( GetCurrentTask() ))) return;
    if (!(pModule = NE_GetPtr( pTask->hModule ))) return;

    /* Initialize implicitly loaded DLLs */
    NE_InitializeDLLs( pTask->hModule );

    if (context)
    {
        /* Registers on return are:
         * ax     1 if OK, 0 on error
         * cx     stack limit in bytes
         * dx     cmdShow parameter
         * si     instance handle of the previous instance
         * di     instance handle of the new task
         * es:bx  pointer to command-line inside PSP
         *
         * 0 (=%bp) is pushed on the stack
         */
        SEGPTR ptr = STACK16_PUSH( pTask->thdb, sizeof(WORD) );
        *(WORD *)PTR_SEG_TO_LIN(ptr) = 0;
        SP_reg(context) -= 2;

        EAX_reg(context) = 1;
        
	if (!pTask->pdb.cmdLine[0]) EBX_reg(context) = 0x80;
	else
        {
            LPBYTE p = &pTask->pdb.cmdLine[1];
            while ((*p == ' ') || (*p == '\t')) p++;
            EBX_reg(context) = 0x80 + (p - pTask->pdb.cmdLine);
        }
        ECX_reg(context) = pModule->stack_size;
        EDX_reg(context) = pTask->nCmdShow;
        ESI_reg(context) = (DWORD)pTask->hPrevInstance;
        EDI_reg(context) = (DWORD)pTask->hInstance;
        ES_reg (context) = (WORD)pTask->hPDB;
    }

    /* Initialize the local heap */
    if ( pModule->heap_size )
    {
        LocalInit16( pTask->hInstance, 0, pModule->heap_size );
    }    

    /* Initialize the INSTANCEDATA structure */
    pSegTable = NE_SEG_TABLE( pModule );
    stacklow = pSegTable[pModule->ss - 1].minsize;
    stackhi  = stacklow + pModule->stack_size;
    if (stackhi > 0xffff) stackhi = 0xffff;
    pinstance = (INSTANCEDATA *)PTR_SEG_OFF_TO_LIN(CURRENT_DS, 0);
    pinstance->stackbottom = stackhi; /* yup, that's right. Confused me too. */
    pinstance->stacktop    = stacklow; 
    pinstance->stackmin    = OFFSETOF( pTask->thdb->cur_stack );
}


/***********************************************************************
 *           WaitEvent  (KERNEL.30)
 */
BOOL16 WINAPI WaitEvent16( HTASK16 hTask )
{
    TDB *pTask;

    if (!hTask) hTask = GetCurrentTask();
    pTask = (TDB *)GlobalLock16( hTask );

    if ( !THREAD_IsWin16( THREAD_Current() ) )
    {
        FIXME(task, "called for Win32 thread (%04x)!\n", THREAD_Current()->teb_sel);
        return TRUE;
    }

    if (pTask->nEvents > 0)
    {
        pTask->nEvents--;
        return FALSE;
    }
    TASK_YieldToSystem();

    /* When we get back here, we have an event */

    if (pTask->nEvents > 0) pTask->nEvents--;
    return TRUE;
}


/***********************************************************************
 *           PostEvent  (KERNEL.31)
 */
void WINAPI PostEvent16( HTASK16 hTask )
{
    TDB *pTask;

    if (!hTask) hTask = GetCurrentTask();
    if (!(pTask = (TDB *)GlobalLock16( hTask ))) return;

    if ( !THREAD_IsWin16( pTask->thdb ) )
    {
        FIXME( task, "called for Win32 thread (%04x)!\n", pTask->thdb->teb_sel );
        return;
    }

    pTask->nEvents++;
    
    if ( !THREAD_IsWin16( THREAD_Current() ) )
    {
        /* wake-up the scheduler waiting in EVENT_WaitNetEvent */
        EVENT_WakeUp();
    }
}


/***********************************************************************
 *           SetPriority  (KERNEL.32)
 */
void WINAPI SetPriority16( HTASK16 hTask, INT16 delta )
{
    TDB *pTask;
    INT16 newpriority;

    if (!hTask) hTask = GetCurrentTask();
    if (!(pTask = (TDB *)GlobalLock16( hTask ))) return;
    newpriority = pTask->priority + delta;
    if (newpriority < -32) newpriority = -32;
    else if (newpriority > 15) newpriority = 15;

    pTask->priority = newpriority + 1;
    TASK_UnlinkTask( hTask );
    TASK_LinkTask( hTask );
    pTask->priority--;
}


/***********************************************************************
 *           LockCurrentTask  (KERNEL.33)
 */
HTASK16 WINAPI LockCurrentTask16( BOOL16 bLock )
{
    if (bLock) hLockedTask = GetCurrentTask();
    else hLockedTask = 0;
    return hLockedTask;
}


/***********************************************************************
 *           IsTaskLocked  (KERNEL.122)
 */
HTASK16 WINAPI IsTaskLocked16(void)
{
    return hLockedTask;
}


/***********************************************************************
 *           OldYield  (KERNEL.117)
 */
void WINAPI OldYield16(void)
{
    TDB *pCurTask = (TDB *)GlobalLock16( GetCurrentTask() );

    if ( !THREAD_IsWin16( THREAD_Current() ) )
    {
        FIXME(task, "called for Win32 thread (%04x)!\n", THREAD_Current()->teb_sel);
        return;
    }

    if (pCurTask) pCurTask->nEvents++;  /* Make sure we get back here */
    TASK_YieldToSystem();
    if (pCurTask) pCurTask->nEvents--;
}


/***********************************************************************
 *           DirectedYield  (KERNEL.150)
 */
void WINAPI DirectedYield16( HTASK16 hTask )
{
    TDB *pCurTask = (TDB *)GlobalLock16( GetCurrentTask() );

    if ( !THREAD_IsWin16( THREAD_Current() ) )
    {
        FIXME(task, "called for Win32 thread (%04x)!\n", THREAD_Current()->teb_sel);
        return;
    }

    TRACE(task, "%04x: DirectedYield(%04x)\n", pCurTask->hSelf, hTask );

    pCurTask->hYieldTo = hTask;
    OldYield16();

    TRACE(task, "%04x: back from DirectedYield(%04x)\n", pCurTask->hSelf, hTask );
}

/***********************************************************************
 *           Yield16  (KERNEL.29)
 */
void WINAPI Yield16(void)
{
    TDB *pCurTask = (TDB *)GlobalLock16( GetCurrentTask() );

    if (pCurTask) pCurTask->hYieldTo = 0;
    if (pCurTask && pCurTask->hQueue) Callout.UserYield16();
    else OldYield16();
}

/***********************************************************************
 *           KERNEL_490  (KERNEL.490)
 */
HTASK16 WINAPI KERNEL_490( HTASK16 someTask )
{
    if ( !someTask ) return 0;

    FIXME( task, "(%04x): stub\n", someTask );
    return 0;
}

/***********************************************************************
 *           MakeProcInstance16  (KERNEL.51)
 */
FARPROC16 WINAPI MakeProcInstance16( FARPROC16 func, HANDLE16 hInstance )
{
    BYTE *thunk,*lfunc;
    SEGPTR thunkaddr;

    if (!func) {
      ERR(task, "Ouch ! MakeProcInstance called with func == NULL !\n");
      return (FARPROC16)0; /* Windows seems to do the same */
    }
    if (!hInstance) hInstance = CURRENT_DS;
    thunkaddr = TASK_AllocThunk( GetCurrentTask() );
    if (!thunkaddr) return (FARPROC16)0;
    thunk = PTR_SEG_TO_LIN( thunkaddr );
    lfunc = PTR_SEG_TO_LIN( func );

    TRACE(task, "(%08lx,%04x): got thunk %08lx\n",
                  (DWORD)func, hInstance, (DWORD)thunkaddr );
    if (((lfunc[0]==0x8c) && (lfunc[1]==0xd8)) ||
    	((lfunc[0]==0x1e) && (lfunc[1]==0x58))
    ) {
    	FIXME(task,"thunk would be useless for %p, overwriting with nop;nop;\n", func );
	lfunc[0]=0x90; /* nop */
	lfunc[1]=0x90; /* nop */
    }
    
    *thunk++ = 0xb8;    /* movw instance, %ax */
    *thunk++ = (BYTE)(hInstance & 0xff);
    *thunk++ = (BYTE)(hInstance >> 8);
    *thunk++ = 0xea;    /* ljmp func */
    *(DWORD *)thunk = (DWORD)func;
    return (FARPROC16)thunkaddr;
}


/***********************************************************************
 *           FreeProcInstance16  (KERNEL.52)
 */
void WINAPI FreeProcInstance16( FARPROC16 func )
{
    TRACE(task, "(%08lx)\n", (DWORD)func );
    TASK_FreeThunk( GetCurrentTask(), (SEGPTR)func );
}


/**********************************************************************
 *	    GetCodeHandle    (KERNEL.93)
 */
HANDLE16 WINAPI GetCodeHandle16( FARPROC16 proc )
{
    HANDLE16 handle;
    BYTE *thunk = (BYTE *)PTR_SEG_TO_LIN( proc );

    /* Return the code segment containing 'proc'. */
    /* Not sure if this is really correct (shouldn't matter that much). */

    /* Check if it is really a thunk */
    if ((thunk[0] == 0xb8) && (thunk[3] == 0xea))
        handle = GlobalHandle16( thunk[6] + (thunk[7] << 8) );
    else
        handle = GlobalHandle16( HIWORD(proc) );

    return handle;
}

/**********************************************************************
 *	    GetCodeInfo    (KERNEL.104)
 */
VOID WINAPI GetCodeInfo16( FARPROC16 proc, SEGINFO *segInfo )
{
    BYTE *thunk = (BYTE *)PTR_SEG_TO_LIN( proc );
    NE_MODULE *pModule = NULL;
    SEGTABLEENTRY *pSeg = NULL;
    WORD segNr;

    /* proc is either a thunk, or else a pair of module handle
       and segment number. In the first case, we also need to
       extract module and segment number. */

    if ((thunk[0] == 0xb8) && (thunk[3] == 0xea))
    {
        WORD selector = thunk[6] + (thunk[7] << 8);
        pModule = NE_GetPtr( GlobalHandle16( selector ) );
        pSeg = pModule? NE_SEG_TABLE( pModule ) : NULL;

        if ( pModule )
            for ( segNr = 0; segNr < pModule->seg_count; segNr++, pSeg++ )
                if ( GlobalHandleToSel16(pSeg->hSeg) == selector )
                    break;

        if ( pModule && segNr >= pModule->seg_count )
            pSeg = NULL;
    }
    else
    {
        pModule = NE_GetPtr( HIWORD( proc ) );
        segNr   = LOWORD( proc );

        if ( pModule && segNr < pModule->seg_count )
            pSeg = NE_SEG_TABLE( pModule ) + segNr;
    }

    /* fill in segment information */

    segInfo->offSegment = pSeg? pSeg->filepos : 0;
    segInfo->cbSegment  = pSeg? pSeg->size : 0;
    segInfo->flags      = pSeg? pSeg->flags : 0;
    segInfo->cbAlloc    = pSeg? pSeg->minsize : 0;
    segInfo->h          = pSeg? pSeg->hSeg : 0;
    segInfo->alignShift = pModule? pModule->alignment : 0;
}


/**********************************************************************
 *          DefineHandleTable16    (KERNEL.94)
 */
BOOL16 WINAPI DefineHandleTable16( WORD wOffset )
{
    return TRUE;  /* FIXME */
}


/***********************************************************************
 *           SetTaskQueue  (KERNEL.34)
 */
HQUEUE16 WINAPI SetTaskQueue16( HTASK16 hTask, HQUEUE16 hQueue )
{
    HQUEUE16 hPrev;
    TDB *pTask;

    if (!hTask) hTask = GetCurrentTask();
    if (!(pTask = (TDB *)GlobalLock16( hTask ))) return 0;

    hPrev = pTask->hQueue;
    pTask->hQueue = hQueue;

    TIMER_SwitchQueue( hPrev, hQueue );

    return hPrev;
}


/***********************************************************************
 *           GetTaskQueue  (KERNEL.35)
 */
HQUEUE16 WINAPI GetTaskQueue16( HTASK16 hTask )
{
    TDB *pTask;

    if (!hTask) hTask = GetCurrentTask();
    if (!(pTask = (TDB *)GlobalLock16( hTask ))) return 0;
    return pTask->hQueue;
}

/***********************************************************************
 *           SetThreadQueue  (KERNEL.463)
 */
HQUEUE16 WINAPI SetThreadQueue16( DWORD thread, HQUEUE16 hQueue )
{
    THDB *thdb = thread? THREAD_IdToTHDB( thread ) : THREAD_Current();
    HQUEUE16 oldQueue = thdb? thdb->teb.queue : 0;

    if ( thdb )
    {
        thdb->teb.queue = hQueue;

        if ( GetTaskQueue16( thdb->process->task ) == oldQueue )
            SetTaskQueue16( thdb->process->task, hQueue );
    }

    return oldQueue;
}

/***********************************************************************
 *           GetThreadQueue  (KERNEL.464)
 */
HQUEUE16 WINAPI GetThreadQueue16( DWORD thread )
{
    THDB *thdb = NULL;
    if ( !thread )
        thdb = THREAD_Current();
    else if ( HIWORD(thread) )
        thdb = THREAD_IdToTHDB( thread );
    else if ( IsTask16( (HTASK16)thread ) )
        thdb = ((TDB *)GlobalLock16( (HANDLE16)thread ))->thdb;

    return (HQUEUE16)(thdb? thdb->teb.queue : 0);
}

/***********************************************************************
 *           SetFastQueue  (KERNEL.624)
 */
VOID WINAPI SetFastQueue16( DWORD thread, HANDLE hQueue )
{
    THDB *thdb = NULL;
    if ( !thread )
        thdb = THREAD_Current();
    else if ( HIWORD(thread) )
        thdb = THREAD_IdToTHDB( thread );
    else if ( IsTask16( (HTASK16)thread ) )
        thdb = ((TDB *)GlobalLock16( (HANDLE16)thread ))->thdb;

    if ( thdb ) thdb->teb.queue = (HQUEUE16) hQueue;
}

/***********************************************************************
 *           GetFastQueue  (KERNEL.625)
 */
HANDLE WINAPI GetFastQueue16( void )
{
    THDB *thdb = THREAD_Current();
    if (!thdb) return 0;

    if (!thdb->teb.queue)
        Callout.InitThreadInput16( 0, THREAD_IsWin16(thdb)? 4 : 5 );

    if (!thdb->teb.queue)
        FIXME( task, "(): should initialize thread-local queue, expect failure!\n" );

    return (HANDLE)thdb->teb.queue;
}

/***********************************************************************
 *           SwitchStackTo   (KERNEL.108)
 */
void WINAPI SwitchStackTo16( WORD seg, WORD ptr, WORD top )
{
    TDB *pTask;
    STACK16FRAME *oldFrame, *newFrame;
    INSTANCEDATA *pData;
    UINT16 copySize;

    if (!(pTask = (TDB *)GlobalLock16( GetCurrentTask() ))) return;
    if (!(pData = (INSTANCEDATA *)GlobalLock16( seg ))) return;
    TRACE(task, "old=%04x:%04x new=%04x:%04x\n",
                  SELECTOROF( pTask->thdb->cur_stack ),
                  OFFSETOF( pTask->thdb->cur_stack ), seg, ptr );

    /* Save the old stack */

    oldFrame = THREAD_STACK16( pTask->thdb );
    /* pop frame + args and push bp */
    pData->old_ss_sp   = pTask->thdb->cur_stack + sizeof(STACK16FRAME)
                           + 2 * sizeof(WORD);
    *(WORD *)PTR_SEG_TO_LIN(pData->old_ss_sp) = oldFrame->bp;
    pData->stacktop    = top;
    pData->stackmin    = ptr;
    pData->stackbottom = ptr;

    /* Switch to the new stack */

    /* Note: we need to take the 3 arguments into account; otherwise,
     * the stack will underflow upon return from this function.
     */
    copySize = oldFrame->bp - OFFSETOF(pData->old_ss_sp);
    copySize += 3 * sizeof(WORD) + sizeof(STACK16FRAME);
    pTask->thdb->cur_stack = PTR_SEG_OFF_TO_SEGPTR( seg, ptr - copySize );
    newFrame = THREAD_STACK16( pTask->thdb );

    /* Copy the stack frame and the local variables to the new stack */

    memmove( newFrame, oldFrame, copySize );
    newFrame->bp = ptr;
    *(WORD *)PTR_SEG_OFF_TO_LIN( seg, ptr ) = 0;  /* clear previous bp */
}


/***********************************************************************
 *           SwitchStackBack   (KERNEL.109)
 */
void WINAPI SwitchStackBack16( CONTEXT *context )
{
    TDB *pTask;
    STACK16FRAME *oldFrame, *newFrame;
    INSTANCEDATA *pData;

    if (!(pTask = (TDB *)GlobalLock16( GetCurrentTask() ))) return;
    if (!(pData = (INSTANCEDATA *)GlobalLock16(SELECTOROF(pTask->thdb->cur_stack))))
        return;
    if (!pData->old_ss_sp)
    {
        WARN( task, "No previous SwitchStackTo\n" );
        return;
    }
    TRACE(task, "restoring stack %04x:%04x\n",
		 SELECTOROF(pData->old_ss_sp), OFFSETOF(pData->old_ss_sp) );

    oldFrame = THREAD_STACK16( pTask->thdb );

    /* Pop bp from the previous stack */

    BP_reg(context) = *(WORD *)PTR_SEG_TO_LIN(pData->old_ss_sp);
    pData->old_ss_sp += sizeof(WORD);

    /* Switch back to the old stack */

    pTask->thdb->cur_stack = pData->old_ss_sp - sizeof(STACK16FRAME);
    SS_reg(context)  = SELECTOROF(pData->old_ss_sp);
    ESP_reg(context) = OFFSETOF(pData->old_ss_sp) - sizeof(DWORD); /*ret addr*/
    pData->old_ss_sp = 0;

    /* Build a stack frame for the return */

    newFrame = THREAD_STACK16( pTask->thdb );
    newFrame->frame32 = oldFrame->frame32;
    if (TRACE_ON(relay))
    {
        newFrame->entry_ip = oldFrame->entry_ip;
        newFrame->entry_cs = oldFrame->entry_cs;
    }
}


/***********************************************************************
 *           GetTaskQueueDS  (KERNEL.118)
 */
void WINAPI GetTaskQueueDS16( CONTEXT *context )
{
    DS_reg(context) = GlobalHandleToSel16( GetTaskQueue16(0) );
}


/***********************************************************************
 *           GetTaskQueueES  (KERNEL.119)
 */
void WINAPI GetTaskQueueES16( CONTEXT *context )
{
    ES_reg(context) = GlobalHandleToSel16( GetTaskQueue16(0) );
}


/***********************************************************************
 *           GetCurrentTask   (KERNEL.36)
 */
HTASK16 WINAPI GetCurrentTask(void)
{
    return THREAD_InitDone? PROCESS_Current()->task : 0;
}

DWORD WINAPI WIN16_GetCurrentTask(void)
{
    /* This is the version used by relay code; the first task is */
    /* returned in the high word of the result */
    return MAKELONG( GetCurrentTask(), hFirstTask );
}


/***********************************************************************
 *           GetCurrentPDB   (KERNEL.37)
 *
 * UNDOC: returns PSP of KERNEL in high word
 */
DWORD WINAPI GetCurrentPDB16(void)
{
    TDB *pTask;

    if (!(pTask = (TDB *)GlobalLock16( GetCurrentTask() ))) return 0;
    return MAKELONG(pTask->hPDB, 0); /* FIXME */
}


/***********************************************************************
 *           GetInstanceData   (KERNEL.54)
 */
INT16 WINAPI GetInstanceData16( HINSTANCE16 instance, WORD buffer, INT16 len )
{
    char *ptr = (char *)GlobalLock16( instance );
    if (!ptr || !len) return 0;
    if ((int)buffer + len >= 0x10000) len = 0x10000 - buffer;
    memcpy( (char *)GlobalLock16(CURRENT_DS) + buffer, ptr + buffer, len );
    return len;
}


/***********************************************************************
 *           GetExeVersion   (KERNEL.105)
 */
WORD WINAPI GetExeVersion16(void)
{
    TDB *pTask;

    if (!(pTask = (TDB *)GlobalLock16( GetCurrentTask() ))) return 0;
    return pTask->version;
}


/***********************************************************************
 *           SetErrorMode16   (KERNEL.107)
 */
UINT16 WINAPI SetErrorMode16( UINT16 mode )
{
    TDB *pTask;
    UINT16 oldMode;

    if (!(pTask = (TDB *)GlobalLock16( GetCurrentTask() ))) return 0;
    oldMode = pTask->error_mode;
    pTask->error_mode = mode;
    pTask->thdb->process->error_mode = mode;
    return oldMode;
}


/***********************************************************************
 *           SetErrorMode32   (KERNEL32.486)
 */
UINT WINAPI SetErrorMode( UINT mode )
{
    return SetErrorMode16( (UINT16)mode );
}


/***********************************************************************
 *           GetDOSEnvironment   (KERNEL.131)
 */
SEGPTR WINAPI GetDOSEnvironment16(void)
{
    TDB *pTask;

    if (!(pTask = (TDB *)GlobalLock16( GetCurrentTask() ))) return 0;
    return PTR_SEG_OFF_TO_SEGPTR( pTask->pdb.environment, 0 );
}


/***********************************************************************
 *           GetNumTasks   (KERNEL.152)
 */
UINT16 WINAPI GetNumTasks16(void)
{
    return nTaskCount;
}


/***********************************************************************
 *           GetTaskDS   (KERNEL.155)
 *
 * Note: this function apparently returns a DWORD with LOWORD == HIWORD.
 * I don't think we need to bother with this.
 */
HINSTANCE16 WINAPI GetTaskDS16(void)
{
    TDB *pTask;

    if (!(pTask = (TDB *)GlobalLock16( GetCurrentTask() ))) return 0;
    return pTask->hInstance;
}

/***********************************************************************
 *           GetDummyModuleHandleDS   (KERNEL.602)
 */
VOID WINAPI GetDummyModuleHandleDS16( CONTEXT *context )
{
    TDB *pTask;
    WORD selector;

    AX_reg( context ) = 0;
    if (!(pTask = (TDB *)GlobalLock16( GetCurrentTask() ))) return;
    if (!(pTask->flags & TDBF_WIN32)) return;

    selector = GlobalHandleToSel16( pTask->hModule );
    DS_reg( context ) = selector;
    AX_reg( context ) = selector;
}

/***********************************************************************
 *           IsTask   (KERNEL.320)
 */
BOOL16 WINAPI IsTask16( HTASK16 hTask )
{
    TDB *pTask;

    if (!(pTask = (TDB *)GlobalLock16( hTask ))) return FALSE;
    if (GlobalSize16( hTask ) < sizeof(TDB)) return FALSE;
    return (pTask->magic == TDB_MAGIC);
}


/***********************************************************************
 *           SetTaskSignalProc   (KERNEL.38)
 *
 * Real 16-bit interface is provided by the THUNK_SetTaskSignalProc.
 */
FARPROC16 WINAPI SetTaskSignalProc( HTASK16 hTask, FARPROC16 proc )
{
    TDB *pTask;
    FARPROC16 oldProc;

    if (!hTask) hTask = GetCurrentTask();
    if (!(pTask = (TDB *)GlobalLock16( hTask ))) return NULL;
    oldProc = (FARPROC16)pTask->userhandler;
    pTask->userhandler = (USERSIGNALPROC)proc;
    return oldProc;
}


/***********************************************************************
 *           SetSigHandler   (KERNEL.140)
 */
WORD WINAPI SetSigHandler16( FARPROC16 newhandler, FARPROC16* oldhandler,
                           UINT16 *oldmode, UINT16 newmode, UINT16 flag )
{
    FIXME(task,"(%p,%p,%p,%d,%d), unimplemented.\n",
	  newhandler,oldhandler,oldmode,newmode,flag );

    if (flag != 1) return 0;
    if (!newmode) newhandler = NULL;  /* Default handler */
    if (newmode != 4)
    {
        TDB *pTask;

        if (!(pTask = (TDB *)GlobalLock16( GetCurrentTask() ))) return 0;
        if (oldmode) *oldmode = pTask->signal_flags;
        pTask->signal_flags = newmode;
        if (oldhandler) *oldhandler = pTask->sighandler;
        pTask->sighandler = newhandler;
    }
    return 0;
}


/***********************************************************************
 *           GlobalNotify   (KERNEL.154)
 *
 * Note that GlobalNotify does _not_ return the old NotifyProc
 * -- contrary to LocalNotify !!
 */
VOID WINAPI GlobalNotify16( FARPROC16 proc )
{
    TDB *pTask;

    if (!(pTask = (TDB *)GlobalLock16( GetCurrentTask() ))) return;
    pTask->discardhandler = proc;
}


/***********************************************************************
 *           GetExePtr   (KERNEL.133)
 */
static HMODULE16 GetExePtrHelper( HANDLE16 handle, HTASK16 *hTask )
{
    char *ptr;
    HANDLE16 owner;

      /* Check for module handle */

    if (!(ptr = GlobalLock16( handle ))) return 0;
    if (((NE_MODULE *)ptr)->magic == IMAGE_OS2_SIGNATURE) return handle;

      /* Search for this handle inside all tasks */

    *hTask = hFirstTask;
    while (*hTask)
    {
        TDB *pTask = (TDB *)GlobalLock16( *hTask );
        if ((*hTask == handle) ||
            (pTask->hInstance == handle) ||
            (pTask->hQueue == handle) ||
            (pTask->hPDB == handle)) return pTask->hModule;
        *hTask = pTask->hNext;
    }

      /* Check the owner for module handle */

    owner = FarGetOwner16( handle );
    if (!(ptr = GlobalLock16( owner ))) return 0;
    if (((NE_MODULE *)ptr)->magic == IMAGE_OS2_SIGNATURE) return owner;

      /* Search for the owner inside all tasks */

    *hTask = hFirstTask;
    while (*hTask)
    {
        TDB *pTask = (TDB *)GlobalLock16( *hTask );
        if ((*hTask == owner) ||
            (pTask->hInstance == owner) ||
            (pTask->hQueue == owner) ||
            (pTask->hPDB == owner)) return pTask->hModule;
        *hTask = pTask->hNext;
    }

    return 0;
}

HMODULE16 WINAPI GetExePtr( HANDLE16 handle )
{
    HTASK16 dummy;
    return GetExePtrHelper( handle, &dummy );
}

void WINAPI WIN16_GetExePtr( CONTEXT *context )
{
    WORD *stack = PTR_SEG_OFF_TO_LIN(SS_reg(context), SP_reg(context));
    HANDLE16 handle = (HANDLE16)stack[2];
    HTASK16 hTask = 0;
    HMODULE16 hModule;

    hModule = GetExePtrHelper( handle, &hTask );

    AX_reg(context) = CX_reg(context) = hModule;
    if (hTask) ES_reg(context) = hTask;
}

/***********************************************************************
 *           TaskFirst   (TOOLHELP.63)
 */
BOOL16 WINAPI TaskFirst16( TASKENTRY *lpte )
{
    lpte->hNext = hFirstTask;
    return TaskNext16( lpte );
}


/***********************************************************************
 *           TaskNext   (TOOLHELP.64)
 */
BOOL16 WINAPI TaskNext16( TASKENTRY *lpte )
{
    TDB *pTask;
    INSTANCEDATA *pInstData;

    TRACE(toolhelp, "(%p): task=%04x\n", lpte, lpte->hNext );
    if (!lpte->hNext) return FALSE;
    pTask = (TDB *)GlobalLock16( lpte->hNext );
    if (!pTask || pTask->magic != TDB_MAGIC) return FALSE;
    pInstData = (INSTANCEDATA *)PTR_SEG_OFF_TO_LIN( pTask->hInstance, 0 );
    lpte->hTask         = lpte->hNext;
    lpte->hTaskParent   = pTask->hParent;
    lpte->hInst         = pTask->hInstance;
    lpte->hModule       = pTask->hModule;
    lpte->wSS           = SELECTOROF( pTask->thdb->cur_stack );
    lpte->wSP           = OFFSETOF( pTask->thdb->cur_stack );
    lpte->wStackTop     = pInstData->stacktop;
    lpte->wStackMinimum = pInstData->stackmin;
    lpte->wStackBottom  = pInstData->stackbottom;
    lpte->wcEvents      = pTask->nEvents;
    lpte->hQueue        = pTask->hQueue;
    strncpy( lpte->szModule, pTask->module_name, 8 );
    lpte->szModule[8]   = '\0';
    lpte->wPSPOffset    = 0x100;  /*??*/
    lpte->hNext         = pTask->hNext;
    return TRUE;
}


/***********************************************************************
 *           TaskFindHandle   (TOOLHELP.65)
 */
BOOL16 WINAPI TaskFindHandle16( TASKENTRY *lpte, HTASK16 hTask )
{
    lpte->hNext = hTask;
    return TaskNext16( lpte );
}


/***********************************************************************
 *           GetAppCompatFlags16   (KERNEL.354)
 */
DWORD WINAPI GetAppCompatFlags16( HTASK16 hTask )
{
    return GetAppCompatFlags( hTask );
}


/***********************************************************************
 *           GetAppCompatFlags32   (USER32.206)
 */
DWORD WINAPI GetAppCompatFlags( HTASK hTask )
{
    TDB *pTask;

    if (!hTask) hTask = GetCurrentTask();
    if (!(pTask=(TDB *)GlobalLock16( (HTASK16)hTask ))) return 0;
    if (GlobalSize16(hTask) < sizeof(TDB)) return 0;
    return pTask->compat_flags;
}