REAL TIME OPERATING SYSTEM PROGRAMMING-II: Real time Linux, Windows CE and OSEK

REAL TIME OPERATING SYSTEM

PROGRAMMING-II: Real time Linux,

Windows CE and OSEK

Lesson-3:

Windows Embedded Compact 13 and

Windows CE Programming Features

and Basics

Windows Embedded 8



Four versions are Windows 8

Embedded Standard, Pro, Industry and

Automotive



Windows 8 Embedded features small

footprint, rich touch- enabled

experiences, device management,

security and analysing functions

Windows Embedded Compact 2013



Supports rich touch-and gesture

enabled inputs, and Visual Studio 2012

and hard real-time support, small

footprint devices that require flexible

hardware, the use of touch- and

Windows Programming

• Window class an instance of which defines

a Window (object).

• Basic coordinates x and y, and z-parameter.

• z ─ specifies whether window is over and

below other windows

• Specification for visibility (show or hide or

no activate).

Windows procedures

• Share the attributes, for example,

Commandshow.

Windows Controls



Windows Controls─ functions of

command, menu, toolbar bars

Notifications to Windows

• Windows based application program

(API) is written to respond or activate

on changes from the current state on

pushing of notification (s) from the

OS.

• OS monitors all input sources (for

example, stylus tap, virtual (on touch

screen or physical key press).

Notifications to Windows

• A notification occurs on an event

• All notifications are sent to the

Windows

• A notification sends the message to a

API

• Messages are placed in queue for the

Windows APIs

Examples of OS Notifications to

Windows

• The OS notifies that a key has been

pressed or a button has been clicked or

command has been received for

redrawing the Windows screen.

• Differs from Unix, where it is other

way round. The application program

asks for the input(s) from the OS for a

character or commands or inputs from

the keyboard.

Windows Programming



Win32 APIs



Windows uses handle in many

procedures (functions)



Handle─ a reference to an interface,

for example for a Window, file or

thread or port. [ An interface is an

unimplemented procedure (function or

method) the codes for which are

Windows Handle



Handle example is INSTANCE of a

Window.



INSTANCE is an object, which is used as a

Handle



Handle is also used as a pointer, called

option pointer.



The option pointer is pointer which points

to a pointer of one of the several sets of the

codes, which run on selecting the option

Windows Handle Inheritance



Windows support (WCE does not)

Handle inheritance



Handle inheritance─ a Handle can be

extended to create a new Handle,

which inherits the variables, properties

and procedures of parent handle and

adds, overrides and overloads new

variables, properties and procedures

2. Windows CE and CE.NET

Programming

Windows CE

• An operating system for handheld

computers and mobile systems,

developed by Microsoft

• Microsoft perception─ compact,

connectable, compatible, companion,

and efficient

• Can also be perceived as Windows for

consumer electronics systems

Windows CE…

• Applications don’t limit to consumer

electronics systems

• One of the most popular OSes for the

handheld systems

• A Windows platform for the systems,

which have resource constraints of

power, memory, touch screen or

display screen size and processing

speeds

Windows CE.NET



Dot NET framework provides for

compiling the managed code



Managed code─ one that is compiled

in CIL (common Intermediate

Language)



CIL gives platform independent CPU

neutral compilation as the byte codes

Windows CE.NET…

•

A runtime environment converts the

byte code instructions into the native

machine and platform instruction

• Bytes code─ can run on different

platforms and be distributed.

Windows CE.NET…

• .NET at runtime verifies the executing

native environment, data source and

destination types, within range array

indices and other functionalities.

CE Main Features Similar to Windows



A Windows based application program is

written to respond or activate or changes

from the current state on pushing of

notification(s) from the OS.



A notification occurs on an event.



The notification sends the message to the

Windows application program.



Messages are placed in queue for the

•

Enables a user to feel, look and interact

with the system using GUIs (graphic

user interfaces) in a manner similar to a

PC running on Windows

•

Unicode 16-bit characters for

International characters and languages

•

Functionalities for hard real time

scheduling

Windows CE Threads



Support to 256 levels of thread

priorities



Provides for the adjustable time

quantum for the threads



Provides for the equal time slice for

the threads of equal priority

Use of ISRs and ISTs



ISTs (interrupt service threads) in

addition to ISRs.



ISTs─ are put in priority queue of

threads waiting for execution.



IST ─ the slow-level interrupt-service

thread of a fast-level ISR

Interrupt latencies



Low interrupt latencies for ISRs and

ISTs

Power Manager



Software to reduce the power

dissipation by reducing clock speed or

running Wait or Stop instruction or

optimizing use of caches or stopping

screen or reduced intensity displays

after limited wait for user input.

Virtual Memory



Virtual memory addresses allocated for

stored programs which may be of size

more than physical memory size.

File-based registry and

several file systems



Flash memory based file system



UDF 2.5 and exFAT file system

Shared source and source code access



Componentization─ two software layers.



One sublayer consists of Microsoft

developed source codes of WCE kernel and

is shared with the system or device

manufacturer. Then the manufacturer adds

the remaining part of the kernel according

to the system hardware.



The remaining part is the hardware

Kernel level objects modifications



Freedom to modify without sharing

4. Windows CE 6.0, Windows Mobile 6

and Automotive 5.0

•

For home as well as office systems

•

Cellular networks connectivity .

Processes and VM

•

Number of processes 2

16

up to lower 2

GB virtual memory addresses per

process

•

Upper 2GB kernel VM space

•

Supports device drivers running in user

mode and kernel mode both

Threads



256 levels of thread priorities



Adjustable time quantum for the

threads



Equal time slice for the threads of

equal priority

Windows CE Programming

•

Use of Win32 APIs subset only [for

example, no environment related

functions and environment blocks, no

current directory information at the

Windows CE Programming…



Support small screen system Windows



Support touch screen system Windows



Support no hard-disk, low RAM

memory and use of ROM and flash

memory in the system



Support System -processor─ x86 or

ARM or SuperH, or any other



Support Unicode 16-bit unsigned short

characters

Windows CE Windows controls



Reduced number of Windows

controls compared to personal

computer



New format Windows controls

(functions of command, menu,

toolbar bars provided in one line due

to small screen)

Windows CE Windows controls…



New controls (for example, date and

time picker controls, calendar picker

control, edit control to auto capitalize

first character of a word when keying

in and virtual keyboard) and a

Windows CE Programming



WCE device drivers imported as the

DLLs at runtime



WCE does not support Handle

inheritance and certain security

attributes.

Windows CE.NET Programming…

•

A runtime environment converts the

byte code instructions into the native

machine and platform instruction

• Bytes code─ can run on different

platforms and be distributed.

We learnt

•

Subset of Win32 APIs

• Windows based application program

(API) written to respond or activate on

changes from the current state on

pushing of notification (s) from the

OS.

• OS monitors all input sources (for

example, stylus tap, virtual (on touch

screen) or physical key press).

We learnt



WCE supports the ISRs which pass

the messages to ISTs, which run as

lower priority threads than the ISRs

and ISTs run as priority queue of

threads.



Windows uses handle in many

procedures (functions). WCE does

not support inheritance of Handles

We learnt



New Windows Controls



New format and reduced number of

Windows controls



No support to Handle Inheritance and

certain security attributes



Windows for Small screen , touch screen

system



No hard-disk, low RAM memory and use

End of Lesson-3 of chapter 12 on

Windows and

Windows CE