<?xml version="1.0" encoding="utf-8"?>

<!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->

<!-- This component and the accompanying materials are made available under the terms of the License 

"Eclipse Public License v1.0" which accompanies this distribution, 

and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->

<!-- Initial Contributors:

    Nokia Corporation - initial contribution.

Contributors: 

-->

<!DOCTYPE concept

  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

<concept id="GUID-017A0B4C-3FC2-5CFD-9D81-6A5ABF982D98" xml:lang="en"><title>EZLib

Interface</title><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>The Symbian platform implements compression and decompression with the

open source ZLib library, which uses dynamic Huffman encoding and LZ77 compression. </p>

<p>The user needs to know about the below: </p>

<ul>

<li id="GUID-54501213-E449-5554-BF69-2C5A9FAB5B69"><p><xref href="GUID-017A0B4C-3FC2-5CFD-9D81-6A5ABF982D98.dita#GUID-017A0B4C-3FC2-5CFD-9D81-6A5ABF982D98/GUID-E1C36B5E-1750-5225-92CC-CE9DF8D6C981">About EZLib interfaces</xref>  </p> </li>

<li id="GUID-26FF852D-5F70-52D6-9C62-E406CA9138E5"><p><xref href="GUID-017A0B4C-3FC2-5CFD-9D81-6A5ABF982D98.dita#GUID-017A0B4C-3FC2-5CFD-9D81-6A5ABF982D98/GUID-2D4AD89D-501C-52DB-83E9-691F9FA86095">How to select an EZLib interface</xref>  </p> </li>

</ul>

<section id="GUID-E1C36B5E-1750-5225-92CC-CE9DF8D6C981"><title>About EZLib

interfaces</title> <p>The EZLib interfaces accomodates the following libraries: </p> <ul>

<li id="GUID-E730EA7A-1C78-592D-AFB1-15BC4178E5FE"><p>ZLib : It is the original

open source code, written in C and slightly modified to run on the Symbian

platform. </p> </li>

<li id="GUID-C3AD9FDD-A3CA-50FE-B93D-75845C8E1F97"><p>EZLib : It consists

of a direct interface to the original C API and a C++ wrapper round that same

API. </p> <p>Earlier versions of EZLib are still supported by the Symbian

platform but are deprecated for new development. The current implementation

is backwards compatible with previous ones. </p> </li>

</ul> <p>EZLib consists of the following dlls: </p> <ul>

<li id="GUID-421EBE71-9F2E-57C8-9989-437781822668"><p>libz.dll, a set of C

APIs with the functionality of ZLib version 1.2.3. </p> </li>

<li id="GUID-7108B065-C9CD-5DC6-89CA-2F81F847BEF0"><p>ezlib.dll, a set of

C++ APIs with the same functionality as the C APIs, packaged to offer different

variations of the functionality. </p> </li>

<li id="GUID-7445BFDB-D54E-5ED2-9081-5975709F7C98"><p>ezip.dll, a set of C++

APIs with the same functionality as the C APIs, packaged to offer different

variations of the functionality. </p> </li>

</ul> </section>

<section id="GUID-2D4AD89D-501C-52DB-83E9-691F9FA86095"><title>How to select

an EZLib interface</title> <p>DLLs are used to implement the EZLib interface

features. </p> <p>Symbian Developers must therefore decide about the interfaces

(C or C++) and DLLs to be used. </p> <ul>

<li id="GUID-0AB51ACE-999E-5EB2-BF67-443BD60F790B"><p>If you want to read

from a zip archive you must use C++ and include ezip.dll because this functionality

is specific to the Symbian platform and is not part of the open source ZLib

library. </p> </li>

<li id="GUID-59EE6445-2DA3-5716-90BC-C2EE6DF4BE51"><p>If you are writing client

applications to run purely on the Symbian platform you must use C++. </p> </li>

<li id="GUID-2E16494D-7DDE-5063-A3B0-640F359DF4D1"><p>If you are integrating

an existing application which already interfaces to the open source version

of zlib you must choose C. </p> </li>

<li id="GUID-768ADF17-B2B1-5933-91ED-6E5759E14255"><p>If you are writing a

cross-platform application to run on various platforms including the Symbian

platform you should probably choose C. </p> </li>

<li id="GUID-915F6514-1421-53C8-B11C-0DC73C1B9C3D"><p>If you simply want the

compression and decompression functionality without file input and output

you should include ezlib.dll. This DLL excludes the API functions with names

beginning in gz such as gzread() and gzwrite() supplying the I/O functionality

known as gzio. The Symbian platform which previously used EZlib

does not use gzio and you should chooose ezlib.dll when working with it. </p> </li>

<li id="GUID-9AB5CEB8-19FB-574E-B56E-E7312CF53815"><p>If you want gzio input

and output functionality you should choose libz.dll. However, use of this

DLL entails memory and performance overheads so you should only use it if

you definitely need the additional functionality. </p> </li>

</ul> <p>The appropriate header file must be included in the application to

implement your choice of DLL. </p> </section>

</conbody><related-links>

<link href="GUID-4BEFF7BA-2A39-5601-919E-22AF08D06023.dita"><linktext>Zip Compression

Library Overview</linktext></link>

<link href="GUID-84922B27-FDCF-56FD-91ED-5E0BFE3ED0E4.dita"><linktext>Compressing

and Decompressing                 File - Zip Format </linktext></link>

<link href="GUID-548CC331-8E38-5627-A925-EA386BE90258.dita"><linktext>Compressing

and Decompressing                 File - GZip Format </linktext></link>

<link href="GUID-C3086910-D7B4-5549-BF65-374C8B602E8F.dita"><linktext>Compressing

and                 Decompressing Memory Streams </linktext></link>

<link href="GUID-FDDAF8E9-4CAB-5489-B578-A5362E2140C1.dita"><linktext>Decompressing

File Archives</linktext></link>

</related-links></concept>