systems programming - lecture 04

8/4/2019 Systems Programming - Lecture 04

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Windows System Programing

Systems Programming

The Basics

October 10, 2009

Aamir Pare


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Agenda

Operating System Essentials

Windows API

Hardware Abstraction LayerWindows Principles

Win64


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Deep Thought for the Day

There are only 10 types of people in this

world those who understand binary, and

those who dont.


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Computer Architecture

Layered View of OS


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Operating Systems

What is an operating system?

Where do we find operating systems?


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Operating System Features

Memory

File systems

Resource naming and locationMultitasking

Communication and synchronization

Security and protection


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The Kernel

Central component of an OS

Manages resources

Interface between software andhardware

Provides lowest level abstraction layer

that applications must controlMemory, Processor, I/O


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The Kernel

Kernel and other OS Objects


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Hardware Abstraction Layer (HAL)

Enables porting to different processor architectures

Primary architecture: x86 (Intel), AMD

64-bit processors

Intel Itanium, AMD Athlon64 and Opteron64 (AMD64)

Intel 64-bit x86 extensions

Other architectures

Windows Mobile and Windows CE run on mobileplatforms

Windows NT was originally supported on DEC Alpha


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Windows API

Application Programming Interface (API)

Makes the OS components available

Has its own set of conventions andprogramming techniques

Scalable

EvolvingAlso known as Win32 API


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Windows API

Functional Categories

Administration and Management

Diagnostics

Graphics and Multimedia

Networking

Security

System Services

Windows User Interface


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Other APIs

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 servicesStandard threading library

Supported by NT Kernel


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Windows Principles

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

Many system resources are represented as a kernelobjectidentified and referenced by a handle

Function calls will often have numerous parameters and

flags, many of which can normally be ignored


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Windows Principles

Windows offers numerous synchronization and

communication mechanisms tailored for

different requirements

The threadis the basic unit of execution. Aprocess can contain one or more threads.

Windows function names are long and

descriptiveWaitForSingleObject

WaitForSingleObjectEx

WaitForMultipleObjects

WaitNamedPipe


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Windows Principles

Conventions for type names

Predefined data types, required by the

API, are in uppercase and descriptive

BOOL

HANDLE

DWORDLPTSTR

LPSECURITY_ATTRIBUTES

Many others


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Naming Conventions (cont.)

Predefined types avoid the * operator and make distinctionssuch as differentiatingLPTSTR(defined as TCHAR *)

LPTCTSTR(defined as const TCHAR *)

Variable names in function prototypes also haveconventionslpszFileName

Long pointer to a zero-terminated stringdwAccess

A double word (32 bits) containing file access flags

dw denotes flags in a double word


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Naming Conventions (cont.)

The Windows API is backward compatible withthe Win16 API

The long pointer is simply a 32-bit or 64-bitpointer.

Win32 sometimes appears in macro names(WIN32_FIND_DATA) even though the macro isalso used with Win64

Numerous 16-bit functions are available, but

should not be usedOpenFile(16-bit)

CreateFile(32-bit)


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Win64 vs Win32

Main differences

Size of the pointer variables

Size of the virtual address space232= 4294967296

4 GB264= 18446744073709551616

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

Be careful about assumptions concerning pointers and

integers being the same sizeDWORD32 and DWORD64 are defined

POINTER_32 and POINTER_64 control pointer size


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When to use C

Most file processing can be done using ANSI Standard Clibrary

Why use C, instead of Windows system calls?

Portability

Why use Windows system calls?

More powerful

Better performance

Additional capabilityFile locking

Memory mapping

Asynchronous I/O

Inter-process Communication


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Example

Sequential File Copy

Using C

Using WindowsUsing convenience function


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Review

Operating System Essentials

Windows API

Hardware Abstraction LayerWindows Principles

Win64

Development Environment Setup andDemo

systems programming - lecture 04

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