- Saved the state of the fpu at a win32 call and restored the state 
  after the call to the previous state.

reactos/ntoskrnl/ke/i386

diff -u -r1.17 -r1.18
--- fpu.c	25 Nov 2004 13:22:54 -0000	1.17
+++ fpu.c	27 Nov 2004 16:12:26 -0000	1.18
@@ -1,4 +1,4 @@

-/* $Id: fpu.c,v 1.17 2004/11/25 13:22:54 blight Exp $

+/* $Id: fpu.c,v 1.18 2004/11/27 16:12:26 hbirr Exp $

  *
  *  ReactOS kernel
  *  Copyright (C) 1998, 1999, 2000, 2001 ReactOS Team

@@ -403,6 +403,44 @@

   return STATUS_SUCCESS;
 }
 

+VOID
+KiClearFloatingPointState(BOOLEAN Save)
+{
+   PKTHREAD CurrentThread;
+   PFX_SAVE_AREA FxSaveArea;
+
+   ASSERT(KeGetCurrentIrql() >= DISPATCH_LEVEL);
+
+   CurrentThread = KeGetCurrentThread();
+
+   if (CurrentThread->NpxState & NPX_STATE_DIRTY)
+   {
+      if (Save)
+      {
+         FxSaveArea = (PFX_SAVE_AREA)((char *)CurrentThread->InitialStack - sizeof (FX_SAVE_AREA));
+         if (FxsrSupport)
+         {
+            asm volatile("fxsave %0" : : "m"(FxSaveArea->U.FxArea));
+         }
+         else
+         {
+            asm volatile("fnsave %0" : : "m"(FxSaveArea->U.FnArea));
+         }
+         CurrentThread->NpxState = NPX_STATE_VALID;
+      }
+      else
+      {
+         CurrentThread->NpxState = NPX_STATE_INVALID;
+      }
+      Ke386SetCr0(Ke386GetCr0() | X86_CR0_TS);
+   }
+   if (KeGetCurrentKPCR()->PrcbData.NpxThread == CurrentThread)
+   {
+      KeGetCurrentKPCR()->PrcbData.NpxThread = NULL;
+   }
+}
+  
+

 NTSTATUS
 KiHandleFpuFault(PKTRAP_FRAME Tf, ULONG ExceptionNr)
 {

reactos/ntoskrnl/ps

diff -u -r1.18 -r1.19
--- w32call.c	20 Nov 2004 23:46:37 -0000	1.18
+++ w32call.c	27 Nov 2004 16:12:26 -0000	1.19
@@ -1,4 +1,4 @@

-/* $Id: w32call.c,v 1.18 2004/11/20 23:46:37 blight Exp $

+/* $Id: w32call.c,v 1.19 2004/11/27 16:12:26 hbirr Exp $

  *
  * COPYRIGHT:              See COPYING in the top level directory
  * PROJECT:                ReactOS kernel

@@ -45,6 +45,7 @@

   PKTRAP_FRAME SavedTrapFrame;
   PVOID SavedCallbackStack;
   PVOID SavedExceptionStack;

+  BYTE SavedNpxState;

 } NTW32CALL_SAVED_STATE, *PNTW32CALL_SAVED_STATE;
 
 typedef struct

@@ -83,6 +84,7 @@

   PKTRAP_FRAME SavedTrapFrame;
   PVOID SavedCallbackStack;
   PVOID SavedExceptionStack;

+  BYTE SavedNpxState;

 
   Thread = PsGetCurrentThread();
   if (Thread->Tcb.CallbackStack == NULL)

@@ -105,7 +107,7 @@

   SavedTrapFrame = State->SavedTrapFrame;
   SavedCallbackStack = State->SavedCallbackStack;
   SavedExceptionStack = State->SavedExceptionStack;

-

+  SavedNpxState = State->SavedNpxState;

   /*
    * Copy the callback status and the callback result to NtW32Call
    */

@@ -127,20 +129,14 @@

    * Restore the old stack.
    */
   KeRaiseIrql(HIGH_LEVEL, &oldIrql);

-  if ((Thread->Tcb.NpxState & NPX_STATE_VALID) &&
-      ETHREAD_TO_KTHREAD(Thread) != KeGetCurrentKPCR()->PrcbData.NpxThread)
-    {
-      memcpy((char*)InitialStack - sizeof(FX_SAVE_AREA),
-             (char*)Thread->Tcb.InitialStack - sizeof(FX_SAVE_AREA),
-             sizeof(FX_SAVE_AREA));
-    }

+  KiClearFloatingPointState(FALSE);
+  Thread->Tcb.NpxState = SavedNpxState;

   Thread->Tcb.InitialStack = InitialStack;
   Thread->Tcb.StackBase = StackBase;
   Thread->Tcb.StackLimit = StackLimit;
   Thread->Tcb.TrapFrame = SavedTrapFrame;
   Thread->Tcb.CallbackStack = SavedCallbackStack;
   KeGetCurrentKPCR()->TSS->Esp0 = (ULONG)SavedExceptionStack;

-  Ke386SetCr0(Ke386GetCr0() | X86_CR0_TS); /* set TS */

   KeStackSwitchAndRet((PVOID)(OldStack + 1));
 
   /* Should never return. */

@@ -243,6 +239,7 @@

 	}
       return(NULL);
     }

+  DPRINT1("KernelStack %x\n", KernelStack);

   return(KernelStack);
 }
 

@@ -288,9 +285,7 @@

       AssignedStack = CONTAINING_RECORD(StackEntry, NTW32CALL_CALLBACK_STACK,
 					ListEntry);
       NewStack = AssignedStack->BaseAddress;

-
-      MmUpdatePageDir(PsGetCurrentProcess(), NewStack, StackSize);
-

+      memset(NewStack, 0, StackSize);

     }
   /* FIXME: Need to check whether we were interrupted from v86 mode. */
   memcpy((char*)NewStack + StackSize - sizeof(KTRAP_FRAME) - sizeof(FX_SAVE_AREA),

@@ -316,17 +311,15 @@

   SavedState.SavedTrapFrame = Thread->Tcb.TrapFrame;
   SavedState.SavedCallbackStack = Thread->Tcb.CallbackStack;
   SavedState.SavedExceptionStack = (PVOID)KeGetCurrentKPCR()->TSS->Esp0;

-  if ((Thread->Tcb.NpxState & NPX_STATE_VALID) &&
-      ETHREAD_TO_KTHREAD(Thread) != KeGetCurrentKPCR()->PrcbData.NpxThread)
-    {
-      memcpy((char*)NewStack + StackSize - sizeof(FX_SAVE_AREA),
-             (char*)SavedState.SavedInitialStack - sizeof(FX_SAVE_AREA),
-             sizeof(FX_SAVE_AREA));
-    }

+
+  KiClearFloatingPointState(TRUE);
+
+  SavedState.SavedNpxState = Thread->Tcb.NpxState;

   Thread->Tcb.InitialStack = Thread->Tcb.StackBase = (char*)NewStack + StackSize;
   Thread->Tcb.StackLimit = (ULONG)NewStack;
   Thread->Tcb.KernelStack = (char*)NewStack + StackSize - sizeof(KTRAP_FRAME) - sizeof(FX_SAVE_AREA);
   KeGetCurrentKPCR()->TSS->Esp0 = (ULONG)Thread->Tcb.InitialStack - sizeof(FX_SAVE_AREA);

+  Thread->Tcb.NpxState = NPX_STATE_INVALID;

   KePushAndStackSwitchAndSysRet((ULONG)&SavedState, Thread->Tcb.KernelStack);
 
   /* 

reactos/ntoskrnl/include/internal/i386

diff -u -r1.6 -r1.7
--- fpu.h	20 Nov 2004 23:46:36 -0000	1.6
+++ fpu.h	27 Nov 2004 16:12:26 -0000	1.7
@@ -78,6 +78,9 @@

 BOOL
 KiContextToFxSaveArea(PFX_SAVE_AREA FxSaveArea, PCONTEXT Context);
 

+VOID
+KiClearFloatingPointState(BOOLEAN Save);
+

 #endif /* !__ASM__ */
 
 #endif /* __NTOSKRNL_INCLUDE_INTERNAL_I386_FPU_H */