static DWORD WINAPI
TclWinThreadStart(
    LPVOID lpParameter)		/* The WinThread structure pointer passed
				 * from TclpThreadCreate */
{
    WinThread *winThreadPtr = (WinThread *) lpParameter;
    unsigned int fpmask;
    LPTHREAD_START_ROUTINE lpOrigStartAddress;
    LPVOID lpOrigParameter;

    if (!winThreadPtr) {
	return TCL_ERROR;
    }

    fpmask = _MCW_EM | _MCW_RC | _MCW_PC;

    _controlfp(winThreadPtr->fpControl, _MCW_EM | _MCW_RC | 0x03000000 /* _MCW_DN */
#if !defined(_WIN64)
#if defined(_MSC_VER) && _MSC_VER >= 1200
    fpmask |= _MCW_DN;
	    | _MCW_PC
#endif

    );
    _controlfp(winThreadPtr->fpControl, fpmask);

    lpOrigStartAddress = winThreadPtr->lpStartAddress;
    lpOrigParameter = winThreadPtr->lpParameter;

    ckfree((char *)winThreadPtr);
    return lpOrigStartAddress(lpOrigParameter);
}