International Components for Unicode
ICU 2.6 ReadMe

Version: 2003-Apr-16
Copyright © 1997-2003 International Business Machines Corporation and others. All Rights Reserved.

Table of Contents

• Introduction
• Getting Started
• What Is New In This release?
• How To Download the Source Code
• ICU Source Code Organization
• How To Build And Install ICU
  • Supported Platforms
  • Windows
  • Windows XP on IA64
  • Unix
  • z/OS (os/390)
  • OS/400 (iSeries)
• How To Package ICU
• Important Notes About Using ICU
  • Using ICU in a Multithreaded Environment
  • How to Make ICU Smaller
  • Using the Default Codepage
  • Windows Platform
  • Unix Type Platforms
• Platform Dependencies

Introduction

Today's software market is a global one in which it is desirable to develop and maintain one application (single source/single binary) that supports a wide variety of languages. The International Components for Unicode (ICU) libraries provide robust and full-featured Unicode services on a wide variety of platforms to help this design goal. The ICU libraries provide support for:

• The latest version of the Unicode standard
• Character set conversions with support for over 200 codepages
• Locale data for more than 230 locales
• Language sensitive text collation (sorting) and searching based on the Unicode Collation Algorithm (=ISO 14651)
• Regular expression matching and Unicode sets
• Transformations for normalization, upper/lowercase, script transliterations (50+ pairs)
• Resource bundles for storing and accessing localized information
• Date/Number/Message formatting and parsing of culture specific input/output formats
• Calendar specific date and time manipulation
• Complex text layout for Arabic, Hebrew, Indic and Thai
• Text boundary analysis for finding characters, word and sentence boundaries

ICU has a sister project ICU4J that extends the internationalization capabilities of Java to a level similar to ICU. The ICU C/C++ project is also called ICU4C when a distinction is necessary.

Getting started

This document describes how to build and install ICU on your machine. For other information about ICU please see the following table of links.
The ICU homepage also links to related information about writing internationalized software.

Important: Please make sure you understand the Copyright and License Information.

What is new in this release?

The following list concentrates on changes that affect existing applications migrating from previous ICU releases. For more news about this release, see the ICU 2.6 download page.

ICU code library size

ICU code libraries can be made smaller by removing functionality. See How to Make ICU Smaller.

Support for Unicode 3.2

Unicode properties and algorithms have been upgraded to Unicode 3.2, which includes the addition of more than 1000 new encoded characters. The UCA (Unicode Collation Algorithm) table is updated to the current version 3.1.1, with Unicode 3.2-based canonical closure. All Unicode properties (except for those in Unihan.txt) are now available via direct APIs, and most via UnicodeSet.

Flexible data loading

ICU 2.2 has an extended search path functionality, more flexible data override capabilities, and removes lesser-known heuristics for determining the data path.

• Performance: ICU will only load data from packages, not from single files, when the search path is empty. This eliminates all file system accesses after the packages (ICU data + application data) are loaded.
  If this is important, then an application should set the search path to the empty path during initialization.
• Customizability: If the search path is not empty, then ICU searches for single files before looking in packages, allowing to override/update packaged data.
• User data: The new function ucnv_openPackage allows an application to load an ICU character mapping table from its own data. This enables applications to support more codepages than the ICU installation that it uses.
• Separation between ICU data and user data: Single data files must now always have a package name as prefix, which results in different file names between ICU and all application packages even for the same locale IDs etc.
• Multi-path: The search path can now contain multiple folders and can list packages directly instead of just a single folder.
• Predictability: The search path can be set via the ICU_DATA environment variable or via the u_setDataDirectory() function.
  ICU does not perform any other heuristics any more.

Note: while some of the old binary data may be still readable by ICU 2.2 (resource bundles, for example), they need to be repackaged in order to be used.

• If you have individual binary files, you have to rename them so that you prepend a 'packagename_'. Then use packagename for opening.
• If you have a memory-mapped package file, you will need to unpack it (use decmn tool), rename individual files as above (prepending the package name), and repack the files.
• If you have a shared library file, you'll need to somehow get individual files and repackage them.

Experimental locales moved to new repository

Experimental locales are ones for which we have incomplete data. Data for such locales used to be included in the default ICU download, but have been moved to a new locale data repository, stored as another ICU CVS module. This data can be added back into a customized ICU build, see the User Guide Data chapter. It can also still be viewed with the LocaleExplorer demo.

How To Download the Source Code

There are two ways to download ICU releases:

• Official Release Snapshot:
  If you want to use ICU (as opposed to developing it), you should download an official packaged version of the ICU source code. These versions are tested more thoroughly than day-to-day development builds of the system, and they are packaged in zip and tar files for convenient download. These packaged files can be found at http://oss.software.ibm.com/icu/download/.
  The packaged snapshots are named icu-nnnn.zip or icu-nnnn.tgz, where nnnn is the version number. The .zip file is used for Windows platforms, while the .tgz file is preferred on most other platforms.
  Please unzip this file. It will reconstruct the source directory, which includes anonymous CVS control directories (see below).
• CVS Source Repository:
  If you are interested in developing features, patches, or bug fixes for ICU, you should probably be working with the latest version of the ICU source code. You will need to check the code out of our CVS repository to ensure that you have the most recent version of all of the files. See our CVS page for details.

ICU Source Code Organization

In the descriptions below, <ICU> is the full path name of the icu directory (the top level directory from the distribution archives) in your file system. You can also view the User's Guide to see which libraries you need for your software product. You need at least the data ([lib]icudt) and the common ([lib]icuuc) libraries in order to use ICU.

How To Build And Install ICU

Supported Platforms

Key to testing frequency

Reference platform

ICU will work on these platforms with these compilers

Regularly tested

ICU should work on these platforms with these compilers

Rarely tested

ICU has been ported to these platforms but may not have been tested there recently

How To Build And Install On Windows

Building International Components for Unicode requires:

• Microsoft NT 4.0 and above, or Windows 98 and above
• Microsoft Visual C++ 6.0 (Service Pack 2 is required to work with the release build of max speed optimization).

(If you want to build with Microsoft Visual C++ .NET, please refer to the note about building with Visual Studio .NET below.)

The steps are:

1. Unzip the icu-XXXX.zip file into any convenient location. Using command line zip, type "unzip -a icu-XXXX.zip -d drive:\directory", or just use WinZip.
2. Be sure that the ICU binary directory, <ICU>\bin\, is included in the PATH environment variable. The tests will not work without the location of the ICU dll files in the path.
3. Set the TZ environment variable to PST8PDT. The tests will not work in any other time zone.
4. Open the "<ICU>\source\allinone\allinone.dsw" workspace file in Microsoft Visual C++ 6.0. (This workspace includes all the International Components for Unicode libraries, necessary ICU building tools, and the intltest and cintltest test suite projects). Please see the note below if you want to build from the command line instead.
5. Set the active Project to the "all" project. To do this: Choose "Project" menu, and select "Set active project". In the submenu, select the "all" workspace.
6. Set the active configuration to "Win32 Debug" or "Win32 Release" (See note below).
7. Choose the "Build" menu and select "Rebuild All". If you want to build the Debug and Release at the same time, see the note below.
8. Run the C++ test suite, "intltest". To do this: set the active project to "intltest", and press F5 to run it.
9. Run the C test suite, "cintltst". To do this: set the active project to "cintltst", and press F5 to run it.
10. Make sure that both "cintltst" and "intltest" passed without any errors. The return codes are non-zero when they do not pass. Visual C++ will display the return codes in the debug tag of the output window. When "intltest" and "cintltest" return 0, it means that everything is installed correctly. You can press Ctrl+F5 on the test project to run the test and see what error messages were displayed (if any tests failed).
11. Reset the TZ environment variable to its original value, unless you plan on testing ICU any further.
12. You are now able to develop applications with ICU by using the libraries and tools in <ICU>\bin\. The headers are in <ICU>\include\ and the link libraries are in <ICU>\lib\. To install the ICU runtime on a machine, or ship it with your application, copy the needed components from <ICU>\bin\ to a location on the system PATH or to your application directory.

Using MSDEV At The Command Line Note: You can build ICU from the command line. Assuming that you have properly installed Microsoft Visual C++ to support command line execution, you can run the following command, 'msdev <ICU>\source\allinone\allinone.dsw /MAKE "ALL"'.

Setting Active Configuration Note: To set the active configuration, two different possibilities are:

• Choose "Build" menu, select "Set Active Configuration", and select "Win32 Release" or "Win32 Debug".
• Another way is to select "Customize" in the "Tools" menu, select the "Toolbars" tab, enable "Build" instead of "Build Minibar", and click on "Close". This will bring up a toolbar which you can move aside the other permanent toolbars at the top of the MSVC window. The advantage is that you now have an easy-to-reach pop-up menu that will always show the currently selected active configuration. Or, you can drag the project and configuration selections and drop them on the menu bar for later selection.

Batch Configuration Note: If you want to build the Debug and Release configurations at the same time, choose "Build" menu and select "Batch Build..." instead (and mark all configurations as checked), then click the button named "Rebuild All". The "all" workspace will build all the libraries, test programs and various ICU tools (e.g. genrb for generating binary locale data files).

Microsoft Visual Studio .NET Note: ICU will build with Microsoft Visual Studio .NET, though this is not a supported platform at the time of this writing. Visual Studio .NET will offer to convert the project files when you open the existing workspace file. Choose "Yes to All" in the dialog asking whether to convert the files or not (this creates new files) and then follow the rest of the build instructions.

How To Build And Install On Windows XP on IA64

Building International Components for Unicode requires:

• Microsoft XP on an IA64 (Itanium®) machine
• Microsoft Visual C++ 6.0 (Service Pack 2 is required to work with the release build of max speed optimization).
• Microsoft Platform SDK.

The steps are:

1. Follow steps 1-3 in the in the previous section.
2. Open the "Set Windows XP 64-bit Build Environment (Retail)" command window from the Microsoft Platform SDK.
3. Use cd to get into the <ICU> directory.
4. Run this command: 'msdev /USEENV <ICU>\source\allinone\allinone.dsw /MAKE "all - Win64 Release"'
5. Run "cd source\test\intltest\Release"
6. Run the C++ test suite, "intltest". There should be no errors.
7. Run "cd ..\..\cintltst\Release"
8. Run the C test suite, "cintltst". There should be no errors.
9. Follow the last two steps in the in the previous section.

How To Build And Install On Unix

Building International Components for Unicode on Unix requires:

• A C++ compiler installed on the target machine (for example: gcc, CC, xlC_r, aCC, cxx, etc...).
• An ANSI C compiler installed on the target machine (for example: cc).
• A recent version of GNU make (3.77+).
• For a list of z/OS tools please view the z/OS build section of this document for further details.

Here are the steps to build ICU:

1. Decompress the icu-X.Y.tgz (or icu-X.Y.tar.gz) file. For example, "gunzip -d < icu-X.Y.tgz | tar xvf -"
2. Change directory to the "icu/source".
3. Run "chmod +x runConfigureICU configure install-sh" because these files may have the wrong permissions.
4. Run the runConfigureICU script for your platform. (See note below).
5. Type "gmake" (or "make" if GNU make is the default make on your platform) to compile the libraries and all the data files. The proper name of the GNU make command is printed at the end of the configuration run, as in "You must use gmake to compile ICU".
6. Optionally, type "gmake check" to run the test suite, which checks for ICU's functionality integrity (See note below).
7. Type "gmake install" to install ICU. If you used the --prefix= option on configure or runConfigureICU, ICU will be installed to the directory you specified. (See note below).

Configuring ICU NOTE: Type "./runConfigureICU --help" for help on how to run it and a list of supported platforms. You may also want to type "./configure --help" to print the available configure options that you may want to give runConfigureICU. If you are not using the runConfigureICU script, or your platform is not supported by the script, you may need to set your CC,CXX, CFLAGS and CXXFLAGS environment variables, and type "./configure". Some of the more frequently used options to configure are --disable-64bit-libs to create 32-bit libraries, and --srcdir to do out of source builds (build the libraries in the current location).

Running The Tests From The Command Line NOTE: You may have to set certain variables if you with to run test programs individually, that is apart from "gmake check". The TZ environment variable needs to be set to PST8PDT. Also, the environment variable ICU_DATA can be set to the full pathname of the data directory to indicate where the locale data files and conversion mapping tables are when you are not using the shared library (e.g. by using the .dat archive or the individual data files). The trailing "/" is required after the directory name (e.g. "$Root/source/data/out/" will work, but the value "$Root/source/data/out" is not acceptable). You do not need to set ICU_DATA if the complete shared data library is in your library path.

Installing ICU NOTE: Some platforms use package management tools to control the installation and uninstallation of files on the system, as well as the integrity of the system configuration. You may want to check if ICU can be packaged for your package management tools by looking into the "packaging" directory. (Please note that if you are using a snapshot of ICU from CVS, it is probable that the packaging scripts or related files are not up to date with the contents of ICU at this time, so use them with caution).

How To Build And Install On z/OS (OS/390)

You can install ICU on z/OS or OS/390 (the previous name of z/OS), but IBM tests only the z/OS installation. These platforms commonly are called "MVS". You install ICU in a z/OS UNIX system services file system such as HFS or zFS. On this platform, it is important that you understand a few details:

• APAR PQ58392 may be needed by z/OS 1.2 or 1.3 in order to get some ICU number formatting functions to work properly. The APAR affects C and C++ code.
• The gnu utilities gmake and gzip/gunzip are needed and can be obtained for z/OS from z/OS Unix - Tools and Toys. Documentation on these tools can be found at the Open Source Software for z/OS UNIX Red Book.
• Encoding considerations: The source code assumes that it is compiled with codepage ibm-1047 (to be exact, the UNIX System Services variant of it). The pax command converts all of the source code files from ASCII to codepage ibm-1047 (USS) EBCDIC. However, some files are binary files and must not be converted, or must be converted back to their original state. You can use the unpax-icu.sh script to do this for you automatically. It will unpackage the tar file and convert all the necessary files for you automatically.

• z/OS supports both native S/390 hexadecimal floating point and, (with OS/390 2.6 and later) IEEE binary floating point. This is a compile time option. Applications built with IEEE should use ICU dlls that are built with IEEE (and vice versa). The environment variable IEEE390=1 will cause the z/OS version of ICU to be built with IEEE floating point. The default is native hexadecimal floating point.
  Important: Currently (ICU 1.4.2), native floating point support is sufficient for codepage conversion, resource bundle and UnicodeString operations, but the Format APIs, especially ChoiceFormat, require IEEE binary floating point.

  Examples for configuring ICU:
  Debug build: IEEE390=1 ./runConfigureICU --enable-debug zOS/cxx
  Release build: IEEE390=1 ./runConfigureICU zOS/cxx

• Since the default make on z/OS is not gmake, the pkgdata tool requires that the "make" command is aliased to your installed version of gmake. You may also need to set $MAKE equal to the fully-qualified path of GNU make. GNU make is available with the "z/OS Unix - Tools and Toys" that was mentioned above. The required version is the same Unix build instructions.
• The makedep executable that is used with the z/OS ICU build process is not shipped with ICU. It is available at the z/OS Unix - Tools and Toys site. The PATH environment variable should be updated to contain the location of this executable prior to build. Alternatively, makedep may be moved into an existing PATH directory.
• The rest of the instructions for building and testing ICU on z/OS with Unix System Services are the same as the How To Build And Install On Unix section.

z/OS (Batch/PDS) support outside the UNIX system services environment

By default, ICU builds its libraries into the UNIX file system (HFS). In addition, there is a z/OS specific environment variable (OS390BATCH) to build some libraries into the z/OS native file system. This is useful, for example, when your application is externalized via Job Control Language (JCL).

The OS390BATCH environment variable enables non-UNIX support including the batch environment. When OS390BATCH is set, the libicuucXX.dll, libicudtXXe.dll, and libicudtXXe_stub.dll binaries are built into data sets (the native file system). Turning on OS390BATCH does not turn off the normal z/OS UNIX build. This means that the The z/OS UNIX (HFS) dlls will always be created.

Two additional environment variables indicate the names of the z/OS data sets to use. The LOADMOD environment variable identifies the name of the data set that contains the dynamic link libraries (DLLs) and the LOADEXP environment variable identifies the name of the data set that contains the side decks, which are normally the files with the .x suffix in the UNIX file system.

A data set is roughly equivalent to a UNIX or Windows file. For most kinds of data sets the operating system maintains record boundaries. UNIX and Windows files are byte streams. Two kinds of data sets are PDS and PDSE. Each data set of these two types contains a directory. It is like a UNIX directory. Each "file" is called a "member". Each member name is limited to eight bytes, normally EBCDIC.

Here is an example of some environment variables that you can set prior to building ICU:

OS390BATCH=1
LOADMOD=USER.ICU.LOAD
LOADEXP=USER.ICU.EXP

The PDS member names for the DLL file names are as follows:

IXMIXXUC --> libicuucXX.dll
IXMIXXDA --> libicudtXXe.dll
IXMIXXD1 --> libicudtXXe_stub.dll (Only when OS390_STUBDATA=1)

You should point the LOADMOD environment variable at a partitioned data set extended (PDSE) and point the LOADEXP environment variable at a partitioned data set (PDS). The PDSE can be allocated with the following attributes:

Data Set Name . . . : USER.ICU.LOAD
Management class. . : **None**
Storage class . . . : BASE
Volume serial . . . : TSO007
Device type . . . . : 3390
Data class. . . . . : LOAD
Organization  . . . : PO
Record format . . . : U
Record length . . . : 0
Block size  . . . . : 32760
1st extent cylinders: 1
Secondary cylinders : 5
Data set name type  : LIBRARY

The PDS can be allocated with the following attributes:

Data Set Name . . . : USER.ICU.EXP
Management class. . : **None**
Storage class . . . : BASE
Volume serial . . . : TSO007
Device type . . . . : 3390
Data class. . . . . : **None**
Organization  . . . : PO
Record format . . . : FB
Record length . . . : 80
Block size  . . . . : 3200
1st extent cylinders: 3
Secondary cylinders : 3
Data set name type  : PDS

How To Build And Install On OS/400 (iSeries)

ICU Reference Release 2.4 contains partial support for the iSeries platform. After building ICU and running the tests, you may notice that some of the formatting tests fail. The formating failures can be ignored for now. These failures are expected to be resolved in a future release of OS/400.

Before you start building ICU, ICU requires the following:

• QSHELL interpreter installed (install base option 30, operating system)
• ILE C/C++ Compiler for iSeries, LPP 5722-WDS
• The latest GNU facilities (You can get the GNU facilities for OS/400 from http://www.as400.ibm.com/developer/factory/porting/gnu_utilities.html). Older versions may not work properly.

The following describes how to setup and build ICU. For background information, you should look at the Unix build instructions.

1. Create AS400 target library. This library will be the target for the resulting modules, programs and service programs. You will specify this library on the OUTPUTDIR environment variable in step 2.
   

   CRTLIB LIB(libraryname)
   

   
   
2. Set up the following environment variables in your build process (use the libraryname from the previous step)

   ADDENVVAR ENVVAR(CC) VALUE('/usr/bin/icc')
   ADDENVVAR ENVVAR(CXX) VALUE('/usr/bin/icc')
   ADDENVVAR ENVVAR(MAKE) VALUE('/usr/bin/gmake')
   ADDENVVAR ENVVAR(OUTPUTDIR) VALUE('libraryname')
   

   libraryname identifies target as400 library for *module, *pgm and *srvpgm objects.
   
   
3. In order to get the tests to run correctly, the QUTCOFFSET needs to be set to the Pacific Time Zone offset.
   
   To check your QUTCOFFSET:

   DSPSYSVAL SYSVAL(QUTCOFFSET)
   

   
   To change your QUTCOFFSET:
   

   CHGSYSVAL SYSVAL(QUTCOFFSET) VALUE('-0800')
   

   You should change -0800 to -0700 for daylight savings.
   
   
4. Run 'CHGJOB CCSID(37)'
5. Run 'QSH'
6. Run gunzip on the ICU source code compressed tar archive (icu-X.Y.tgz or icu-X.Y.tar.gz).
7. Run unpax-icu.sh on the tar file from the ICU download page.
8. Change your current directory to icu/source.
9. Run 'export CFLAGS=-O4 CXXFLAGS=-O4' to optimize your build of ICU. If the build fails, rerun these build steps without this step before asking the icu4c-support mailing list for help.
10. Run 'cp ../as_is/os400/configure .'
11. Run './configure --host=as400-os400'
12. If you specified --with-data-packaging=archive to configure, you can skip this step. In a future release of ICU, we hope to eliminate this complicated step. Any suggestions to improve the ICU installation are greatly appreciated, and you can send those suggestions to the icu4c-support mailing list.
    1. Run 'mv data/Makefile data/Makefile.hide'
    2. Run 'gmake' to build some of the ICU libraries.
    3. When the gmake command fails in icu/source/data, run the following commands to setup and build the data library:

       cd data
       mv Makefile.hide Makefile
       system CRTLIB "LIB(datalibraryname)"
       gmake OUTPUTDIR=datalibraryname
       system CRTSRVPGM "SRVPGM(libraryname/LIBICUDATA)" "MODULE(datalibraryname/*ALL)"
                        "EXPORT(*ALL)" "TEXT('ICU 2.4 DATA')" "OPTION(*DUPPROC *DUPVAR)"
       ln -fs /qsys.lib/libraryname.lib/libicudata.srvpgm out/libicudata.o
       cd ..
       del common/libicuuc.o
       
       

    4. Your data library should now be usable. Go to the next step, which is needed to rebind to the actual data library and finish the build.
13. Run 'gmake' to build ICU.
14. Run 'gmake check' to build the tests.
15. The "utility/MultithreadTest" test in intltest may have failed during 'gmake check'. In order to make this test pass, please use 'gmake check QIBM_MULTI_THREADED=Y' after you built the tests with 'gmake check' from the previous step. You can look at the iSeries Information Center for more details.

How To Package ICU

There are many ways that a person can package ICU with their software products. Usually only the libraries need to be considered for packaging.

On Unix, you should have used "gmake install" to make it easier to develop and package ICU. The bin, lib and include directories are needed to develop applications that use ICU. These directories will be created relative to the "--prefix=dir" configure option (See above). When ICU is built on Windows, a similar directory structure is built.

When changes have been made to the standard ICU distribution, it is recommended that at least one of the following guidelines be followed for special packaging.

1. Add a suffix name to the library names. This can be done with the --with-library-suffix configure option.
2. The installation script should install the ICU libraries into the application's directory.

Following these guidelines prevents other applications that use a standard ICU distribution from conflicting any libraries that you need. On operating systems that do not have a standard C++ ABI (name mangling) for compilers, it is recommended to do this special packaging anyway. More details on customizing ICU are available in the User's Guide. The ICU Source Code Organization section of this readme.html gives a more complete description of the libraries.

Normally only the above ICU libraries need to be considered for packaging. The versionless symbolic links to these libraries are only needed for easier development. The X, Y and Z parts of the name are the version numbers of ICU. For example, ICU 2.0.2 would have the name libicuuc.so.20.2 for the common library. The exact format of the library names can vary between platforms due to how each platform can handles library versioning.

Important Notes About Using ICU

Using ICU in a Multithreaded Environment

If you are using ICU in a multithreaded application, there may be a chance that the ICU global mutex is not initialized properly. Normally the ICU global mutex is initialized during C++ static initialization, but there are some compilers and linkers that do not properly perform C++ static initialization in a library. Here are some of the cases when the global mutex is not initialized:

• Static ICU libraries are used.
• ICU is used on Mac OS X
• ICU is used on HP-UX and the program's main() function is not declared in a C++ file.

Upon the first usage of most ICU APIs, the global mutex will get initialized. For example, you could call uloc_countAvailable() or uloc_getDefault() from your main() function before any threads are created. Those functions will initialize the global mutex. Without one of these function calls from a single thread, the data caches inside ICU may get initialized more than once, which may cause memory leaks and other problems. This problem normally does not happen when C++ static initialization works properly.

ICU does not use C++ static initialization for anything else, and disabling threads in ICU will disable all C++ static initialization in ICU. If you do not have a multithreaded application, you do not need to worry about the global mutex.

How to Make ICU Smaller

For some environments, ICU "is too large". There are two ways to remove parts and make it smaller: Remove some of its library code modules from the build (reducing functionality), or remove some of its data (possibly reducing only codepage/locale/etc. coverage without sacrificing overall functionality). For details about reducing the data size see the User Guide "ICU Data" chapter.

The header file source/common/unicode/uconfig.h contains source-code-level "switches" corresponding to #if directives in the ICU source code. Setting one of the UCONFIG_NO_... switches to 1 (by setting CFLAGS/CPPFLAGS or adding a #define at the beginning of uconfig.h) turns off the code associated with one of the ICU service modules. Setting one of the UCONFIG_ONLY_... switches to 1 turns off all modules that are not essential for the functioning of the associated "only" service. For the current set of available switches see uconfig.h itself.

When a source code module is turned off, then the data-building makefiles should be modified to not generate the data files that are used with that module. Some of the data-generating genxyz tools rely on the module itself to build its data; they will generate dummy data files to satisfy the dependencies of the unmodified makefiles (to make these switches easily testable). Other data files for which the tools do not rely on the related library modules (e.g., mapping tables [.cnv] and transliterator files [.res, from source/data/translit/]) continue to be built unless the data makefiles are modified. For further details on data building see the User Guide "ICU Data" chapter.

Using the default codepage

ICU has code to determine the default codepage of the system or process. This default codepage can be used to convert char * strings to and from Unicode.

Depending on system design, setup and APIs, it may not always be possible to find a default codepage that fully works as expected. For example,

• On Windows there are three encodings in use at the same time. Unicode (UTF-16) is always used inside of Windows, while for char * encodings there are two classes, called "ANSI" and "OEM" codepages. ICU will use the ANSI codepage. Note that the OEM codepage is used by default for console window output.
• On some Unix-type systems, non-standard names are used for encodings, or non-standard encodings are used altogether. Although ICU supports 200 encodings in its standard build and many more aliases for them, it will not be able to recognize such non-standard names.
• Some systems do not have a notion of a system or process codepage, and may not have APIs for that.

If you have means of detecting a default codepage name that are more appropriate for your application, then you should set that name with ucnv_setDefaultName() as the first ICU function call. This makes sure that the internally cached default converter will be instantiated from your preferred name.

Starting in ICU 2.0, when a converter for the default codepage cannot be opened, a fallback default codepage name and converter will be used. On most platforms, this will be US-ASCII. For z/OS (OS/390), ibm-1047-s390 is the default fallback codepage. For AS/400 (iSeries), ibm-37 is the default fallback codepage. This default fallback codepage is used when the operating system is using a non-standard name for a default codepage, or the converter was not packaged with ICU. The feature allows ICU to run in unusual computing environments without completely failing.

Windows Platform

If you are building on the Win32 platform, it is important that you understand a few of the following build details.

DLL directories and the PATH setting

As delivered, the International Components for Unicode build as several DLLs, which are placed in the "<ICU>\bin" directory. You must add this directory to the PATH environment variable in your system, or any executables you build will not be able to access International Components for Unicode libraries. Alternatively, you can copy the DLL files into a directory already in your PATH, but we do not recommend this. You can wind up with multiple copies of the DLL and wind up using the wrong one.

Changing your PATH

• Windows 2000: Use the System Icon in the Control Panel. Pick the "Advanced" tab. Select the "Environment Variables..." button. Select the variable PATH in the lower box, and select the lower "Edit..." button. In the "Variable Value" box, append the string ";<ICU>\bin" to the end of the path string. If there is nothing there, just type in "<ICU>\bin". Click the Set button, then the OK button.
• Windows NT: Use the System Icon in the Control Panel. Pick the "Environment" tab, and select the variable PATH in the lower box. In the "value" box, append the string ";<ICU>\bin" at the end of the path string. If there is nothing there, just type in "<ICU>\bin". Click the Set button, then the OK button.
• Windows 95/98/ME: Edit the autoexec.bat, and add the following line to the end of file, "SET PATH=%PATH%;<ICU>\bin"

Note: When packaging a Windows application for distribution and installation on user systems, copies of the ICU DLLs should be included with the application, and installed for exclusive use by the application. This is the only way to insure that your application is running with the same version of ICU, built with exactly the same options, that you developed and tested with. Refer to Microsoft's guidelines on the usage of DLLs, or search for the phrase "DLL hell" on msdn.microsoft.com.

Unix Type Platform

If you are building on a Unix platform, and if you are installing ICU in a non-standard location, you may need to add the location of your ICU libraries to your LD_LIBRARY_PATH or LIBPATH environment variable (or the equivalent runtime library path environment variable for your system). The ICU libraries may not link or load properly without doing this.

Note that if you do not want to have to set this variable, you may instead use the --enable-rpath option at configuration time. This option will instruct the linker to always look for the libraries where they are installed. You will need to use the appropriate linker options when linking your own applications and libraries against ICU, too. Please refer to your system's linker manual for information about runtime paths. The use of rpath also means that when building a new version of ICU you should not have an older version installed in the same place as the new version's installation directory, as the older libraries will used during the build, instead of the new ones, likely leading to an incorrectly build ICU. (This is the proper behavior of rpath.)

Platform Dependencies

The platform dependencies have been mostly isolated into the following files in the common library. This information can be useful if you are porting ICU to a new platform.

• unicode/platform.h.in (autoconf'ed platforms)
  unicode/pXXXX.h (others: pwin32.h, pmacos.h, ..): Platform-dependent typedefs and defines:
  
  
  • XP_CPLUSPLUS for C++ only.
  • TRUE and FALSE, UBool, int8_t, int16_t etc.
  • U_EXPORT and U_IMPORT for specifying dynamic library import and export
  • int64_t and uint64_t. If the platform does not support 64 bit values, the macro U_INT64_T_UNAVAILABLE must be defined. For example, this will disable Rule-based number formatting.
  
  
• unicode/putil.h, putil.c: platform-dependent implementations of various functions that are platform dependent:
  
  
  • uprv_isNaN, uprv_isInfinite, uprv_getNaN and uprv_getInfinity for handling special floating point values.
  • uprv_tzset, uprv_timezone, uprv_tzname and time for getting platform specific time and time zone information.
  • u_getDataDirectory for getting the default data directory.
  • uprv_getDefaultLocaleID for getting the default locale setting.
  • uprv_getDefaultCodepage for getting the default codepage encoding.
  
  
• umutex.h, umutex.c: Code for doing synchronization in multithreaded applications. If you wish to use International Components for Unicode in a multithreaded application, you must provide a synchronization primitive that the classes can use to protect their global data against simultaneous modifications. See Users' guide for more information.
  
  
  • We supply sample implementations for WinNT, Win95, Win98, Sun/Solaris, RedHat/Linux, HP-UX and for AIX on an RS/6000.
  
  
• umapfile.h, umapfile.c: functions for mapping or otherwise reading or loading files into memory. All access by ICU to data from files makes use of these functions.
  
  
• For the intltest test suite, intltest.cpp in "icu/source/test/intltest/" contains the method pathnameInContext, which must also be adapted to any new platform.
• Using platform specific #ifdef macros are highly discouraged outside of the scope of these files. When the source code gets updated in the future, these #ifdef's can cause testing problems for your platform.

It is possible to build each library individually. They must be built in the following order:

1. stubdata
2. common
3. i18n
4. toolutil
5. makeconv
6. gencnval
7. genprops
8. gennames
9. genpname
10. gennorm
11. genbrk
12. genuca
13. genrb
14. gentz
15. genccode
16. gencmn
17. pkgdata
18. makedata (a project on Windows, or source/data/Makefile on Unix)
19. ctestfw, intltest and cintltst, if you want to run the test suite.
20. uconv and ustdio can also be optionally built.

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