README.md 13.1 KB
Newer Older
Tobias Schuele committed
1
Embedded Multicore Building Blocks (EMB²)
2 3 4 5
=========================================


Overview
6
--------
7

Tobias Schuele committed
8 9
The Embedded Multicore Building Blocks (EMB²) are an easy to use yet powerful
and efficient C/C++ library for the development of parallel applications. EMB²
10 11 12 13 14 15 16 17
has been specifically designed for embedded systems and the typical
requirements that accompany them, such as real-time capability and constraints
on memory consumption. As a major advantage, low-level operations are hidden
in the library which relieves software developers from the burden of thread
management and synchronization. This not only improves productivity of
parallel software development, but also results in increased reliability and
performance of the applications.

Tobias Schuele committed
18
EMB² is independent of the hardware architecture (x86, ARM, ...) and runs on
19 20 21 22 23
various platforms, from small devices to large systems containing numerous
processor cores. It builds on MTAPI, a standardized programming interface for
leveraging task parallelism in embedded systems containing symmetric or
asymmetric multicore processors. A core feature of MTAPI is low-overhead
scheduling of fine-grained tasks among the available cores during runtime.
Tobias Schuele committed
24
Unlike existing libraries, EMB² supports task priorities, which allows the
25 26 27 28
creation of soft real-time systems. Additionally, the scheduling strategy can
be optimized for non-functional requirements such as minimal latency and
fairness.

Tobias Schuele committed
29
Besides the task scheduler, EMB² provides basic parallel algorithms, concurrent
30 31 32 33 34 35 36 37 38 39
data structures, and skeletons for implementing stream processing applications
(see figure below). These building blocks are largely implemented in a
non-blocking fashion, thus preventing frequently encountered pitfalls like
lock contention, deadlocks, and priority inversion. As another advantage in
real-time systems, the algorithms and data structures give certain progress
guarantees. For example, wait-free data structures guarantee system-wide
progress which means that every operation completes within a finite number of
steps independently of any other concurrent operations on the same data
structure.

40
<img src="doc/images/embb.png" alt="Building blocks of EMB²" width="500"/>
41 42

Community and Contact
43
---------------------
44

Tobias Schuele committed
45 46
Project home:
  - https://github.com/siemens/embb
47

Tobias Schuele committed
48 49 50
Git:
  - https://github.com/siemens/embb.git (HTTP)
  - git@github.com:siemens/embb.git (SSH)
51

Tobias Schuele committed
52 53 54
Mailing lists:
  - embb-announcements@googlegroups.com (announcements)
  - embb-dev@googlegroups.com (development)
55

Tobias Schuele committed
56 57 58
Subscription:
  - https://groups.google.com/forum/#!forum/embb-announcements/join
  - https://groups.google.com/forum/#!forum/embb-dev/join
59

Tobias Schuele committed
60 61 62
Contact:
  - embb.info@gmail.com or
  - tobias.schuele@siemens.com
63 64 65


License
66
-------
67

Tobias Schuele committed
68
See the file "COPYING.md" in the project's root directory.
69 70 71


Requirements
72
------------
73 74 75 76 77

This project is based on the standards C99 (for C code) and C++03 (for C++
code) to be usable on a wide range of target systems. It has been tested on
the following OS/compiler/architecture combinations:

78
  - Linux (Ubuntu 12.04) / GCC 4.8.1 / x86, x86_64
79
  - Linux (Ubuntu 12.04) / Clang 3.0.0 / x86_64
80 81
  - Linux (Ubuntu 14.04) / GCC 4.8.2 / ARMv7
  - Windows
Tobias Schuele committed
82
    * MSVC 12.0.21005.1 REL / x86, x86_64
83 84 85 86
    * MSVC 11.0.50727.42 VSLRSTAGE / x86, x86_64

Other compilers and operating systems may be supported without any changes to
the source code. The project includes unit tests that can be used to find out
Tobias Schuele committed
87
whether a system not officially supported is suitable to run EMB². If there is
88 89 90 91 92
a requirement to support a system on which the unit tests do not pass, please
contact us: embb-dev@googlegroups.com.


Directory Structure
93
-------------------
94

Tobias Schuele committed
95
EMB² is a technology stack consisting of various building blocks. For some of
96 97
them, there exist C and C++ versions, others are only implemented in C++. The
directory names are postfixed with either "_cpp" or "_c" for  the C++ and C
Tobias Schuele committed
98
versions, respectively. Currently, EMB² contains the following components:
99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120

  - base: base_c, base_cpp
  - mtapi: mtapi_c, mtapi_cpp
  - algorithms: algorithms_cpp
  - dataflow: dataflow_cpp
  - containers: containers_cpp

Each component consists of an include, a src, and a test subfolder that contain
the header files, source files, and unit tests, respectively.

Component base_c contains abstractions for threading, synchronization, atomic
operations, and other functionalities. As the name indicates, the code is
implemented in C. Component base_cpp is mainly a C++ wrapper around the base_c
functionalities. Component mtapi_c is a task scheduler written in C and
mtapi_cpp a C++ wrapper for the scheduler. Component algorithms_cpp provides
high-level constructs for typical parallelization task in C++, and
dataflow_cpp generic skeletons for the development of parallel stream-based
applications. Finally, component containers_cpp provides containers, i.e.,
data structures for storing object in an organized and thread-safe way.


Build and Installation
121
----------------------
122

123 124 125
Note: It is recommended to build from a release file and not from a repository
snapshot in order to get the documentation and the examples out-of-the box.
The release files can be found at https://github.com/siemens/embb/releases.
126

Tobias Schuele committed
127
EMB² is built using CMake (version 2.8.9 or higher). CMake is a build file
128 129 130 131 132 133 134
generator which allows to abstract from the concrete build tools. To generate
and invoke the platform-specific build files, open a shell (on Windows, use
the Visual Studio developer shell to have the correct environment variables)
and change to the project's root directory. Create a subdirectory, where you
want to build the library, e.g., "build". Change to that subdirectory. It is
assumed that the project's root directory is now the parent directory.

135
### 1. Generation of native build files
136 137 138

Choose an appropriate build file generator for your system.

139
  - For Linux, GCC/Clang, x86/x86_64/ARM: "Unix Makefiles"
140 141 142 143 144 145 146 147
  - For Windows, MSVC of VS 2013, x86:    "Visual Studio 12"
  - For Windows, MSVC of VS 2013, x86_64: "Visual Studio 12 Win64"
  - For Windows, MSVC of VS 2012, x86:    "Visual Studio 11"
  - For Windows, MSVC of VS 2012, x86_64: "Visual Studio 11 Win64"

A list of all available generators can be displayed by typing "cmake" without
any options. The build files can be generated using the following command:

Roger Meier committed
148
    cmake -G <generator> .. [OPTIONS]
149 150 151 152 153 154 155

Note that on Linux, the architecture (32/64 bit) cannot be selected by the
generator. However, the build mode (Release/Debug) can be specified using the
option -DCMAKE_BUILD_TYPE=[Release|Debug]. If no build mode is given on Linux,
the default (Release) is used. The Visual Studio generators create build files
for both modes (the selection is done at build time).

156
You may choose a custom compiler instead the default one by defining
157 158
CMAKE_CXX_COMPILER and/or CMAKE_C_COMPILER. For example, to use Clang on Linux
use:
159 160 161

    cmake .. -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_C_COMPILER=clang

162
In the same way you may cross compile to another platform. For example, to cross
163 164
compile to ARM Linux using GCC, you need to specify the cross compiler itself and
the target architecture as an argument to the compiler:
165 166 167 168 169 170

    cmake .. -DCMAKE_CXX_COMPILER=arm-linux-gnueabi-gcc++
             -DCMAKE_CXX_FLAGS=-march=armv7-a
             -DCMAKE_C_COMPILER=arm-linux-gnueabi-gcc
             -DCMAKE_C_FLAGS=-march=armv7-a

Tobias Schuele committed
171
EMB² can be built with and without C++ exception handling, which has to be
172
specified on build file generation. When exceptions are turned off, an error
Tobias Schuele committed
173
message is emitted and the program aborts in case of an exception within EMB².
174 175
To disable exceptions, add the option -DUSE_EXCEPTIONS=OFF.

Tobias Schuele committed
176
The tutorial of EMB² comes with example source files in doc/examples/. These
177 178 179 180 181 182 183 184
can be built with the other source files using CMake option -DBUILD_EXAMPLES=ON
in the generation step. Note, however, that the examples use C++11 features and
require a corresponding compiler.

Now you can generate the build files as shown by the following examples.

For a Linux Debug build with exception handling, type

Roger Meier committed
185
    cmake -G "Unix Makefiles" .. -DCMAKE_BUILD_TYPE=Debug
186 187 188

For a Windows build (VS 2013, x86) without exception handling, type

Roger Meier committed
189
    cmake -G "Visual Studio 12" .. -DUSE_EXCEPTIONS=OFF
190 191 192 193

Note that "Visual Studio 12" refers to the version number of Visual Studio and
not to the year in which it was released (2013).

194
### 2. Compiling and linking
195 196 197 198 199 200 201

As the next step, you can compile the library using the generated build files.
On Linux, the build mode (Release|Debug) is already given in the build files,
whereas on Windows, it has to be specified now.

For a Linux build, type

Roger Meier committed
202
    cmake --build .
203 204 205

For a Windows Release build, type

Roger Meier committed
206
    cmake --build . --config Release
207

208
### 3. Running the tests
209

Tobias Schuele committed
210
To check whether EMB² was compiled correctly, run the tests. The test
211 212 213 214
executables are contained in the subfolder "binaries".

On Linux, type

Roger Meier committed
215
    binaries/run_tests.sh
216 217 218

On Windows, type

Roger Meier committed
219
    binaries\run_tests.bat
220

Tobias Schuele committed
221
If no error message occurs, EMB² is working fine.
222

223
### 4. Installation
224 225 226

The default installation path on Linux is

Roger Meier committed
227
    /usr/local/
228 229 230

and on Windows

Roger Meier committed
231
    C:\Program Files\embb-X.Y.Z\ or C:\Program Files (x86)\embb-X.Y.Z
232 233 234 235 236

depending on the target architecture.

If you want a different installation path, you can change it now by typing

Roger Meier committed
237
    cmake -DINSTALL_PREFIX=YourCustomPath ..
238 239 240 241 242

The option "-DINSTALL_PREFIX=YourCustomPath" can also be given in Step 1.

To install the files, use the command

Roger Meier committed
243
    cmake --build . --target install
244 245 246 247 248 249 250

which copies the contents of the "install" folder to the "bin", "lib", and
"include" folders in the installation path. For the default paths, the
installation has to be run with administrator / root privileges.


Using the Library
251
-----------------
252

Tobias Schuele committed
253
To use EMB², the include files have to be made available during compilation of
254 255
your application and the libraries have to be added during linking.

256
### 1. Using C++
257

Tobias Schuele committed
258
If you want to use the C++ functionalities of EMB², you have to link the
259 260 261
following libraries (names will be different on Windows and on Linux) in the
given order:

Roger Meier committed
262 263
    embb_base, embb_base_cpp, embb_mtapi_c, embb_mtapi_cpp, embb_containers_cpp,
    embb_algorithms_cpp, embb_dataflow_cpp
264 265 266

The C++ header files can be included as follows:

Roger Meier committed
267 268 269 270
    #include<embb/mtapi/mtapi.h>
    #include<embb/base/base.h>
    #include<embb/containers/containers.h>
    #include<embb/dataflow/dataflow.h>
271

272
### 2. Using C
273 274 275

The following libraries have to be linked in the given order:

Roger Meier committed
276
    embb_base_c, mtapi_c
277 278 279

The C header files can be included as follows:

Roger Meier committed
280 281
    #include<embb/mtapi/c/mtapi.h>  or  #include<mtapi.h>
    #include<embb/base/c/base.h>
282 283 284


Documentation
285
-------------
286

Tobias Schuele committed
287
EMB² comes with a tutorial, example programs, and an HTML reference
288 289 290 291 292
documentation describing the APIs, which can be found in the "doc" folder.
The root document of the HTML reference is "doc/reference/index.html".


Code Quality
293
------------
294

Tobias Schuele committed
295
For the C++ parts of EMB², we respect most rules of the "Google C++ Style
296 297 298 299 300 301 302 303 304
Guide" which are checked using the cpplint tool. However, we ignore some
rules, as they are not applicable or yield false results for this project.
For example, we respect the include order of the Google Style Guide, but use
<> instead of "" for project includes, which confuses the cpplint tool.
Moreover, we do not tolerate compiler warnings and regularly check the source
code using Cppcheck, a static analysis tool for C++.


Known Bugs and Limitations
305
--------------------------
306

Tobias Schuele committed
307 308
- The MTAPI implementation is currently limited to homogeneous systems.
  Support for heterogeneous systems will be added in the near future.
Tobias Schuele committed
309
- For memory management reasons, the number of threads EMB² can deal with
Tobias Schuele committed
310 311 312
  is bounded by a predefined but modifiable constant (see functions
  embb_thread_get_max_count() / embb_thread_set_max_count() and class
  embb::base::Thread).
Tobias Schuele committed
313

314

315
Development and Contribution
316
----------------------------
317 318 319 320 321

The EMB² team welcomes all kinds of contributions, preferably as pull requests
or patches via the development mailing lists (see above). If possible, please
refer to a current snapshot of the development branch.

322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347
EMB² is supposed to be easily portable to platforms unsupported so far. Almost
all platform specific code is located in the base_c and base_cpp modules. All
existing platform specific code is fenced by EMBB_PLATFORM_* defines.

To distinguish between compilers, EMB² currently uses the following defines:

  - EMBB_PLATFORM_COMPILER_GNUC
  - EMBB_PLATFORM_COMPILER_MSVC
  - EMBB_PLATFORM_COMPILER_UNKNOWN

Different architectures are distinguished using:

  - EMBB_PLATFORM_ARCH_X86
  - EMBB_PLATFORM_ARCH_X86_32
  - EMBB_PLATFORM_ARCH_X86_64
  - EMBB_PLATFORM_ARCH_ARM
  - EMBB_PLATFORM_ARCH_UNKNOWN

Threading APIs are switched by:

  - EMBB_PLATFORM_THREADING_WINTHREADS
  - EMBB_PLATFORM_THREADING_POSIXTHREADS

Please use these defines for new platform specific code. If additional defines
are needed, they can be defined in the config.h or cmake_config.h.in files.

348

349
Links
350
-----
351 352 353 354 355 356 357

  - Multicore Association:
    http://www.multicore-association.org
  - MTAPI:
    http://www.multicore-association.org/workgroup/mtapi.php
  - CMake:
    http://www.cmake.org/
Tobias Schuele committed
358
  - Google C++ Style Guide:
359 360 361 362 363
    http://google-styleguide.googlecode.com/svn/trunk/cppguide.html
  - cpplint:
    http://google-styleguide.googlecode.com/svn/trunk/cpplint/
  - Cppcheck:
    http://cppcheck.sourceforge.net/