CS222: Systems Programming

(1)

CS222:

Systems Programming

The Basics

January 24, 2008

(2)

 Operating System Essentials

 Windows API

 Hardware Abstraction Layer

 Windows Principles

 Win64

Agenda

(3)

Deep Thought for the Day

 There are only 10 types of people in this world – those who understand binary,

and those who don’t.

(4)

Class Email List

 I will use the email address listed on BanWeb for the class email list

– If you prefer I use another address, email it

to me.

(5)

Computer Architecture

System of Layers

(6)

Operating Systems

 What is an operating system?

 Where do we find operating systems?

(7)

Operating System Features

 Memory

 File systems

 Resource naming and location

 Multitasking

 Communication and synchronization

 Security and protection

(8)

The Kernel

 Central component of an OS

 Manages resources

– Interface between software and hardware

 Provides lowest level abstraction layer that applications must control

– Memory, Processor, I/O

(9)

The Kernel

(10)

Hardware Abstraction Layer (HAL)

 Enables porting to different processor architectures

 Primary architecture: x86 (Intel), AMD

– 64-bit processors

• Intel Itanium, AMD Athlon 64 and Opteron 64 (AMD64)

• Intel 64-bit x86 extensions

 Other architectures

– Windows Mobile and Windows CE run on mobile platforms

– Windows NT was originally supported on DEC Alpha

(11)

Windows API

 Application Programming Interface (API)

– Makes the OS components available – Has its own set of conventions and

programming techniques – Scalable

– Evolving

 Also known as Win32 API

(12)

Windows API

 Functional Categories

– Administration and Management – Diagnostics

– Graphics and Multimedia – Networking

– Security

– System Services

– Windows User Interface

(13)

Other API’s

 POSIX

– “Portable Operating System Interface for uniX”

– Formally designated IEEE 1003

– Specifies user and software interface to the OS

• Standard command line and scripting interface

• User-level programs, services, and utilities

• Program-level services

• Standard threading library

– Supported by NT Kernel

(14)

Windows Principles

 Many system resources are represented as a kernel object identified and referenced by a handle

– Kernel objects must be manipulated by Windows APIs – Objects include files, processes, threads, pipes,

memory mapping, events, etc.

• Objects have security attributes

– Many functions perform the same or similar operations – Function calls will often have numerous parameters

and flags, many of which can normally be ignored

(15)

Windows Principles

– Windows offers numerous synchronization and communication mechanisms tailored for different requirements

– The thread is the basic unit of execution. A process can contain one or more threads.

– Windows function names are long and descriptive

• WaitForSingleObject

• WaitForSingleObjectEx

• WaitForMultipleObjects

• WaitNamedPipe

(16)

Windows Principles

 Conventions for type names

– Predefined data types, required by the API, are in uppercase and descriptive

• BOOL

• HANDLE

• DWORD

• LPTSTR

• LPSECURITY_ATTRIBUTES

• Many others…

(17)

Naming Conventions (cont.)

– Predefined types avoid the * operator and make distinctions such as differentiating

• LPTSTR (defined as TCHAR *)

• LPTCTSTR (defined as const TCHAR *)

– Variable names in function prototypes also have conventions

• lpszFileName

– Long pointer to a zero-terminated string

• dwAccess

– A double word (32 bits) containing file access flags

– “dw” denotes flags in a double word

(18)

Naming Conventions (cont.)

 The Windows API is backward compatible with the Win16 API

– The “long pointer” is simply a 32-bit or 64-bit pointer.

– “Win32” sometimes appears in macro names (WIN32_FIND_DATA) even though the macro is also used with Win64

– Numerous 16-bit functions are available, but should not be used

• OpenFile (16-bit)

(19)

Win64 vs Win32

 Main differences

– Size of the pointer variables

– Size of the virtual address space

• 2

³²

= 4294967296

– 4 GB

• 2

⁶⁴

= 18446744073709551616

– 18 exabytes (kilo, mega, giga, tera, peta, exa)

 Be careful about assumptions concerning pointers and integers being the same size

– DWORD32 and DWORD64 are defined

– POINTER_32 and POINTER_64 control pointer size

(20)

When to use C

 Most file processing can be done using ANSI Standard C library

 Why use C, instead of Windows system calls?

– Portability

 Why use Windows system calls?

– More powerful

– Better performance – Additional capability

• File locking

• Memory mapping

• Asynchronous I/O

• Inter-process Communication

(21)

Example

 Sequential File Copy

– Using C

– Using Windows

– Using convenience function

(22)

Review

 Operating System Essentials

 Windows API

 Hardware Abstraction Layer

 Windows Principles

 Win64

 Development Environment Setup and

Demo

(23)

For next class

 Monday, January 29

– Read Chapter 2 in “Windows System Programming”

 Assignment 1 will be delivered next

week