Source Layout and Description (ICS)

Written by : Nanik (

Repo tag version - android-4.0.3_r1

  1. abi

The content of this directory is not clear what it is about as it contains several C++ files.

  1. bionic

Bionic is mainly a port of the BSD C library to our Linux kernel with the

following additions/changes:

- no support for locales

- no support for wide chars (i.e. multi-byte characters)

- its own smallish implementation of pthreads based on Linux futexes

- support for x86, ARM and ARM thumb CPU instruction sets and kernel interfaces        

This directory contains the different architecture that is supported to use bionic, namely - ARM (under the arch-arm/) and x86 (under the arch-x86/ directory). In order to understand in detail on how to add functions or port it to different architecture you want to read the file OVERVIEW.TXT under the docs/ folder

This directory what looks like a ‘stub’ program that are being used during linking process. The main function of the program is to open a library and read the symbol. The file that contains the main functionality is dlfcn.c under the /bionic/linker/ directory

Contains Math library. Several architecture are supported inside this directory.

This directory contains utility that is used during linking process. The tool is called Android Dynamic Linker what is does is it assign fix addresses to the library to reduce the size of the library and also increases the loading speed. .

  1. bootable

This directory contains a sample bootloader for a fictional SoC. The sample code is to show on how to implement a bootloader for a particular SoC. The directory contains a file called fastboot_protocol.txt which outlines the Fastboot protocol implemented by vendor. There is a good detail explanation about the code in the README file

There is no README file or any such file inside this directory that give some information about the content. Looking at the source code it seems to be code written to write image files into partition,  not sure for what kind of devices.

This directory contains code for creating recovery program. The code inside shows the different things that needs to be implemented. This can be used as a boilerplate to create your own custom recoveries like the ClockworkMod.

  1. build

The main entry point of the build system resides here -, if you follow the instruction in you will see that the first step before you do anything to build Android is to use the command source build/

The script will check few things to make sure all the needed application available in the local machine. It also setup the devices that can be built, which is extracted from the directory device 

This directory contains the heart of the build system, it consists of a number of files with the .mk extension (Makefile). The entry point of the build is the file

This directory contain a program which is written to replace the “cp” command to be used in Android. Not sure what is the rationale behind the use of this program.

This directory contains configuration for the target device that you are planning to build for. Looking at the content of this directory it looks like it is being used for emulators. The files inside this directory looks similar with the device directory where it contains .mk file for board specifics.

This directory contains a number of tools that can be used as part of the build process. [need to investigate later whether the tools inside this directory is used as part of the build process - document tools that are used in the build process].

  1. cts

This directory contains compatibility test suite ( The test coverage are broken down into different folders to cover different parts of Android.

This directory contains applications test suites. The test cases are written in Java and it test different device functionality from application layer such as - USB, sensors, camera, bluetooth, etc

[contains script file but it does not make sense how it is used in the Android build system]

[according to the README file classes were extracted from the project. Looking at the description of the project it is a command line test utility for Java]

This directory contains Java test cases testing different kind of things, mostly on features that are available from Java application.

This directory contains different kind of tools that are available for you to use. The tools are not used in the build process.

  1. dalvik

This directory contains the main Dalvik class that execute the .dex files

The "dexdump" tool is intended to mimic "objdump".  

Home of dexgen, the dex code generator project. It provides API for creating dex classes in runtime which is needed e.g. for class mocking. This solution is based on the dx tool and uses its classes extensively.  

List all methods in all concrete classes in one or more DEX files.

Command-line DEX optimization and verification entry point.

Dalvik documentation

Home of Dalvik eXchange, the thing that takes in class files and reformulates them for consumption in the VM. It also does a few other things; use "dx --help" to see a modicum of self-documentation.

This directory contains program to read HPROF file specific to Android. HPROF is a profiler tool in Android. The application in this directory can be run to read a sample .hprof file in the samples directory.

This directory contains .dex file related tools.

This directory contains support functions for Android's class libraries. These are VM-agnostic native functions that implement methods for system class libraries.  All code here:

 - MUST not be associated with an android.* class (that code lives in


 - SHOULD be written in C rather than C++ where possible.

Some helper functions are defined in include/nativehelper/JNIHelp.h.

This directory contains sets of defined opcodes and instruction formats for Dalvik.

This directory contains test cases to test Dalvik op-codes.

This directory contains Dalvik related tools

This directory contains the core of the Dalvik code.

  1. development

This directory contains application that are not part of the deployed app in the OS. There are some useful application such as widget builder, etc

This directory contains the monkey tool that allows you to inject key events into an app.

This directory contains network carrier information.

This directory contains copyright templates

This directory contains Windows binary files for USB.

This directory contains IDE specific information/configuration. Eclipse, EMacs, IntelliJ and XCode are the IDEs supported.

        From the README.txt

Stereo Camera Libraries for Android. This SDK component contains static libraries for computing the depth map of a pair of stereo images. To use the libraries, simply copy them as static libraries into your project.

This directory contains NDK (Native Development Kit) for Android. This particular directory is not build as part of the Android build process.

This directory contains PDK (Platform Development Kit) for Android. It contains documentation rather than any code.

This directory contains Android application sample files. There are a lot of sample projects that can be used by developers.

Some Google App Engine specific scripts.

This directory contains .properties file related to SDK, can’t figure out what exactly it is used for as there aren’t that much information inside.

Overlay resource files that are used for different device

Utility to run the test cases based on Python.

- remove all private members.

- only include a subset of classes.

- exclude specific classes, fields or methods.

This directory contain a Notepad tutorial application development tutorial.

  1. device

This directory contains gps information and also a script that allows you to extract proprietary binary files from your phone to be part of the build process.

This directory contains the generic device configuration that is called ‘goldfish’. This is the device classification used when building the emulator.

This directory contains the Android Accessories Kit code. It contains a demokit Android app that allows you to control the ADK board. The ADK firmware can be check out here There is a good article about this

This directory contains a full example of writing your own Android platform shared library, without changing the Android framework.  It also shows how to write JNI code for incorporating native code into the library, and a client application that uses the library.

This example is ONLY for people working with the open source platform to create a system image that will be delivered on a device which will include a custom library as shown here.  It can not be used to create a third party shared library, which is not currently supported in Android.

This directory contains Samsung specific configuration

This directory contains TI Pandaboard configuration for build process.

  1. docs

Contains tutorials, references, and miscellaneous information relating to the Android Open Source Project (AOSP). The current iteration of this site is fully static HTML (notably lacking in javascript and doxygen content), and is and/or was maintained by skyler (illustrious intern under Dan Morrill and assistant to the almighty JBQ).

  1. external

Android Mock is a wrapper for EasyMock (2.4) which allows for real Class mocking on

an Android (Dalvik) VM. All methods on Android Mock are syntactically equivalent to EasyMock method calls, and will delegate calls to EasyMock, while performing the required transformations to avoid Dalvik VM troubles.

        From the project website

ANTLR, ANother Tool for Language Recognition, is a language tool that provides a framework for constructing recognizers, interpreters, compilers, and translators from grammatical descriptions containing actions in a variety of target languages.

Apache Harmony software is a modular Java runtime with class libraries and associated tools.

HTTP API for Java from Apache

From project website 

Xalan-Java is an XSLT processor for transforming XML documents into HTML, text, or other XML document types. It implements XSL Transformations (XSLT) Version 1.0 and XML Path Language (XPath) Version 1.0 and can be used from the command line, in an applet or a servlet, or as a module in other program.

ASTL (Android STL) is a slimmed-down version of the regular C++ STL.

This directory contains the Bison parser generator.

This directory contains Block IO Tracing. blktrace was integrated into the mainline kernel between 2.6.16 and 2.6.17-rc1. The website

This directory contains project for Bluetooth communication

This directory contains ported version of encryption project. The document in patches/README outlined the changes made to use it in Android

This directory contains bsdiff and bspatch project. These are tools for building and applying patches to binary files. The project can be found in

This directory contains bzip-1.0.6 from According to the file no changes were made

This directory contains the Chromium project.

This directory contains Clang project. This is a compiler front-end for the C family of languages (C, C++, Objective-C, and Objective-C++) which is built as part of the LLVM

compiler infrastructure project.

This directory contains code for the COLLADA project COLLADA is a royalty-free XML schema that enables digital asset exchange within the interactive 3D industry

This directory contains D-Bus project. D-Bus is a simple system for interprocess communication and coordination.

This is a DHCP client daemon project.

This directory contains the Dnsmasq project - a lightweight, easy to configure DNS forwarder and DHCP server -

This directory contains the Doclava project - a custom Javadoc doclet used to generate documentation. Project page for this

This directory contains  Dropbear, a smallish SSH 2 server and client.

Is a set of utilities for maintaining the ext2, ext3 and ext4 file systems. 

This directory contains easymoch project - a Java library that provides an easy way to use Mock Objects in unit testing with JUnit and TestNG. Project page -

This directory contains varieties of tools and libraries that are related to ELF file.

This directory contains  embunit - a unit testing framework for Embedded C System. Project page -

This directory contains

This directory contains Expat, a C library for parsing XML, written by James Clark.

Expat is a stream-oriented XML parser.  

This directory contains FDLIBM (Freely Distributable LIBM). It is a C math library

for machines that support IEEE 754 floating-point arithmetic. In this release, only double

precision is supported.

This directory contains the source for FLAC project - Free Lossless Audio Codec -

This directory contains code for Freetype project FreeType 2 is a software font engine that is designed to be small, efficient, highly customizable, and portable while capable of producing high-quality output (glyph images).

This directory contains MS-DOS file system check code.

genext2fs generates an ext2 filesystem as a normal (non-root) user. It does not require you to mount the image file to copy files on it, nor does it require that you become the superuser to make device nodes.

This contains the GIF library

This directory contains

This is GNU GRUB, the GRand Unified Bootloader.  GRUB is intended to provide important bootloader features that are missing from typical personal computer BIOSes

Google's framework for writing C++ tests on a variety of platforms (Linux, Mac OS X, Windows, Windows CE, Symbian, and etc).

Guava-libraries are a grab bag of utility libraries published by Google as open source, including among other things the Google collections libraries.

HarfBuzz, an OpenType Layout engine library. 

Hyphen - hyphenation library to use converted TeX hyphenation patterns

ICU is a mature, widely used set of C/C++ and Java libraries providing Unicode and Globalization support for software applications -

This directory contains iproute2, it is a collection of utilities for controlling TCP / IP networking and traffic control in Linux

This directory contains IPsec-Tools project, it is a port of KAME's IPsec utilities to the Linux-2.6 IPsec implementation. Project website

This directory contains iptables project, it is a user space application program that allows a system administrator to configure the tables provided by the Linux kernel firewall

This directory contains the Java JDBC wrapper project for SQLLite.

This directory contains Javassist project. Javassist (JAVA programming ASSISTant) makes Java bytecode manipulation simple. It is a class library for editing bytecodes in Java; it enables Java programs to define a new class at runtime and to modify a class file when the JVM loads it.

This directory contains JDiff Doclet project. The JDiff doclet is used to generate a report describing the difference between two public Java APIs. Project page

This directory contains the jhead project. jhead is an Exif Jpeg header manipulation tool. Project website

This directory contains project for JPEG image compression and decompression.

This directory contains Java wrapper project for the ClearSilver project - ClearSilver is a fast, powerful, and language-neutral HTML template system.

This directory contains the JSR 305 specification implementation. JSR 305 is an  Annotations for Software Defect Detection in Java. Project website

This directory contains JUnit project. This project is a Java testing framework, project website

This directory contains header files for the Linux Kernel.

This directory contains libffi project. The libffi library provides a portable, high level programming interface to various calling conventions.  This allows a programmer to

call any function specified by a call interface description at run time. Project website

This directory contains GSM 06.10 13 kbit/s RPT/LTP implementation. According to the README::

“......we are publishing an implementation of the European GSM 06.10 provisional standard for full-rate speech transcoding, prI-ETS 300 036, which uses RPE/LTP (residual pulse excitation/long term prediction) coding at 13 kbit/s”

This directory contains liblzf project. This project is an extremely fast compression algorithm. Project website

This directory contains NFC library from NXP Semiconductors.

This directory contains network related library. [ Not sure what this project do ?? ]

This directory contains  source code for libpcap, a system-independent interface for user-level packet capture.  libpcap provides a portable framework for low-level network monitoring.  Applications include network statistics collection, security monitoring, network debugging,etc. Project website

This directory contains Google's phone number handling library. Project website

This directory contains library source code for manipulating .png file format.

This directory contains source for vpx Multi-Format Codec SDK. Project website

This directory contains source library for manipulating XML.

This directory contains source code for XSLT toolkit. This project is part of the XML toolkit from the GNOME project. Project website

This directory contains the LLVM project. LLVM project is a Low Level Virtual Machine, a toolkit for the construction of highly optimized compilers,optimizers, and runtime environments. There is an interesting read inside the file that shows some of the issues on the reason why Google can’t push to upstream and also some indication on how to sync to upstream.

This directory contains open source font project called Lohit, it is for Telugu language. The project is hosted in

This directory contains the Markdown project. Markdown is a text-to-HTML conversion tool for web writers. Markdown allows you to write using an easy-to-read, easy-to-write plain text format, then convert it to structurally valid XHTML (or HTML). Project page

This directory contains Mesa 3D project. Mesa is an open-source implementation of the OpenGL specification - a system for rendering interactive 3D graphics. Project website

This directory contains the minimum implemention of the mkshrc application for Android.

This directory contains a library for testing HTTP and HTTPS clients. Project page

This directory contains  ????

From README file:

“Netcat is a simple Unix utility which reads and writes data         across network connections, using TCP or UDP protocol. It is designed to be a reliable "back-end" tool that can be used directly or easily driven by other programs and scripts. “

This directory contains Hewlett Packard netperf tool. According to the project page 

“Netperf is a benchmark that can be use to measure various aspect of networking performance.”

There isn’t much information can be found inside this directory about the project. Reading through the source code and also the filenames it looks like a face recognition library.

This directory contains code for VOIP implementation

This directory contains code for the oauth authentication project code.

This directory contains an optimized port of OpenCV for Android

This directory contains OpenSSL project code for Android. The file contains information on how to port the latest version of OpenSSL

        According to the README file

“This is an alpha release version of oprofile, a transparent low-overhead system-wide profiler.“

This is a Perl-compatible regular expression library project

This directory contains code for the ping command

This directory contains code for the ping command for IPv6

This directory contains code for the ppp protocol

This directory contains ProGuard code. ProGuard is a Java class file shrinker, optimizer, obfuscator, and preverifier

This directory contains Protobuf code. Protobuf is a Google's data interchange format project. Link to the project page -

        This directory contains the QEMU project ( ).

This project has the source code to build two binaries: bios.bin and vgabios-cirrus.bin, which are required for x86 emulation in the Android emulator: platform/external/qemu.

This directory contains source for the Quaker games. The Quake games in this directory is optimized to run on Android

This directory contains source code for the safe-iop project ( ). This library provides a collection of (macro-based) functions for performing safe integer operations across platform and architecture with a straightforward API.

Skia ( ) is a complete 2D graphic library for drawing Text, Geometries, and Images. Features include: 3x3 matrices w/ perspective, antialiasing, transparency, filters, shaders, xfermodes, maskfilters, patheffects.

Sonivox is an embedded audio synthesis project, it contains source code as well binary files for the music. There is quite a lot of documentation inside the /docs folder

Project website according to their website

Speex is an Open Source/Free Software patent-free audio compression format designed for speech. The Speex Project aims to lower the barrier of entry for voice applications by providing a free alternative to expensive proprietary speech codecs. Moreover, Speex is well-adapted to Internet applications and provides useful features that are not present in most other codecs. Finally, Speex is part of the GNU Project and is available under the revised BSD license.

        Project website according to their website

SQLite is a software library that implements a self-contained, serverless, zero-configuration, transactional SQL database engine. SQLite is the most widely deployed SQL database engine in the world. The source code for SQLite is in the public domain

SREC embedded speech recognition engine. There is a doc/ folder containing few .pdf documentation. On reading the documentation the library is from a company NUANCE PROFESSIONAL SERVICES 

Provides an implementation of the Secure Real-time Transport Protocol (SRTP), the Universal Security Transform (UST), and a supporting cryptographic kernel. From the documentation it shows that this project was from Cisco

STLport is a full ANSI C++ Standard library. Project website 

Strace 4.0, a system call tracer for SunOS 4.x, Linux, System V release 4, Solaris 2.x and Irix 5.x. Project website -

        From the documentation

SVOX Pico system is a software solution aimed at enabling Text-to-Speech (TTS) functionalities in low CPU/memory platforms. The Pico core system will be deployed as a set of libraries accessible through an API available to application developers. While benefitting from SVOX knowhow and ‘lessons learned’, SVOX Pico is an entirely new TTS

system designed from scratch and coded in native ANSI-C. This document describes the Pico core system in terms of the underlying design principles, its architecture and main components, and some guidelines for developers who would like to extend Pico’s functionality. (website redirected to Nuance Professional Services website)

        Project website, from the website

This is the home page of TagSoup, a SAX-compliant parser written in Java that, instead of parsing well-formed or valid XML, parses HTML as it is found in the wild: poor, nasty and brutish, though quite often far from short. TagSoup is designed for people who have to process this stuff using some semblance of a rational application design. By providing a SAX interface, it allows standard XML tools to be applied to even the worst HTML. TagSoup also includes a command-line processor that reads HTML files and can generate either clean HTML or well-formed XML that is a close approximation to XHTML.

        From the README file

This directory contains source code for tcpdump, a tool for network monitoring and data acquisition.  This software was originally developed by the Network Research Group at the Lawrence Berkeley National Laboratory.  The original distribution is available via anonymous ftp to, in tcpdump.tar.Z.  More recent development is performed at,

From the README file

a small library to interface with ALSA in the Linux kernel

The aims are:

- Provide a basic pcm and mixer API

- If it's not absolutely needed, don't add it to the API

- Avoid supporting complex and unnecessary operations that could be

  dealt with at a higher level

From readme.txt file

In brief, TinyXml parses an XML document, and builds from that a Document Object Model (DOM) that can be read, modified, and saved.


Tremolo is an ARM optimised version of the Tremor lib from For those that don't know, the Tremor lib is an integer only library for doing Ogg Vorbis decompression.

Javascript engine from Google

        Project website,from the documentation:

The Valgrind tool suite provides a number of debugging and profiling tools that help you make your programs faster and more correct. The most popular of these tools is called Memcheck. It can detect many memory-related errors that are common in C and C++ programs and that can lead to crashes and unpredictable behaviour

Project website from the website:

WebKit is an open source web browser engine. WebKit is also the name of the Mac OS X system framework version of the engine that's used by Safari, Dashboard, Mail, and many other OS X applications. WebKit's HTML and JavaScript code began as a branch of the KHTML and KJS libraries from KDE.

        Project website -, according to README file:

WEBP decoder: is a simple library for decoding WEBP image files.

        Project website -, from the website

WebRTC is a free, open project that enables web browsers with Real-Time Communications (RTC) capabilities via simple Javascript APIs.

Our mission: To enable rich, high quality, RTC applications to be developed in the browser via simple Javascript APIs and HTML5.


wpa_supplicant is a free software implementation of an IEEE 802.11i supplicant for Linux, FreeBSD, NetBSD and Microsoft Windows. In addition to being a full-featured WPA2 supplicant, it also implements WPA and older wireless LAN security protocols.

Looking at the files this folder contains similar project to wpa_supplicant except it could be that the version is older. One thing is obvious there is an extra project included in this folder as per the README file, the project is hostapd 0.6.x

Similar to wpa_supplicant_6 but the version for hostapd is also older (??)

Inside this folder there is only 1 file and the author’s website is

        Project website -, from the website

YAFFS (Yet Another Flash File System) is now in its second generation and provides a fast robust file system for NAND and NOR Flash. It is widely used with Linux and RTOSs, in consumer devices.

Project website -, from the website

A Massively Spiffy Yet Delicately Unobtrusive Compression Library

  1. frameworks

Provides classes for managing DRM content and determining the capabilities of DRM plugins (agents).

Provides low level graphics tools such as canvases, color filters, points, and rectangles that let you handle drawing to the screen directly.

Ported with minor modifications from ICU4J 4.2's class.

Contains classes that define Android location-based and related services.


This directory contains OpenGL ES and EGL extension specifications that have

been or are being defined for Android.

Provides APIs for RTP (Real-time Transport Protocol), allowing applications to manage on-demand or interactive data streaming. In particular, apps that provide VOIP, push-to-talk, conferencing, and audio streaming can use these APIs to initiate sessions and transmit or receive data streams over any available network. 

Provides classes to manage Wi-Fi functionality on the device.

support UI classes for different Android version

  1. hardware

        Broadcom wireless device drivers (binary format).

        Sensors source code

        HAL (Hardware Abstraction Layer) source code

        Legacy hardware interface code

        Qualcomm MSM7000 hardware source code

Qualcomm specific code for media and GPS

Radio Inteface Layer (RIL) interface and sample interface. RIL is the layer for radio based communication like the phone call

Texas Instruments OMAP3 and OMAP4 hardware source code - media framework, camera, security,etc

  1. libcore

VM runtime for Android

        Java test classes for DOM

        Contains information about the test cases

        Some C/C++ include files that used for Array and String handling

        JSON based Java implementation

        JUnit source code

        Contains test source code for loading .jar and .dex files

        Contains support class file for testing Dalvik

        XML pull and push implementation

  1. ndk

        Contains build scripts and helper files for building the NDK

        NDK documentation

        NDK source code and library source

        Test files for testing NDK

        Build file for building the toolchain both for x86 and ARM based platform

  1. packages

Standard Android application that are available as part of the AOSP - Camera, SMS, Dialer, Launcher, etc

Experimental apps that are not part of the AOSP such as RPC, Bugreport, Security tool, etc

        Provider based services application such as - Calendar, Contacts, Media, Telephony, etc

        Input applications

        Standard AOSP wallpaper

  1. prebuilt

Contains prebuilt gdbserver and QEMU kernel

x86 based QEMU kernel for emulator

Common Java open source project that are used during build process

Contains GCC toolchains for compiling Android along with several open source projects

        Android NDK

        Android SDK (.jar file) that normally used by Android apps

        32bit Windows specific files and libraries

        64bit Windows specific ibraries

  1. sdk

This directory contains lots of apps that are not part of operating system. There are quite useful apps that developers can leverage on and can be enhanced further as part of the operating system.

  1. system

This directory contains source for bluetooth

This directory contains number of utilities that are used by Android for maintenance and also during startups such as - adb, mkbootimg, run-as, fastboot, etc.

Contains extra utility and application such as - timeinfo, fat utility, ext4 utility, etc

                Audio related samples and utilties

        Android network daemon

Init startup utility containing several functions such as mounting volume, process handler, device mapper, etc