Simple data-flow programming in C/C++.

CppLink is inspired by Simulink and HAL from the LinuxCNC project. CppLink takes the basics from data-flow programming and presents them in the simplest form available.

CppLink contains two parts - C++ data-flow programming library with predefined modules for data transformation and CppLink translator which translates netlist files into C++ code that simulates the system described by the netlist file.

There are two ways to use CppLink. Either you can use the data-flow C++ library directly and write a C++ code using it, or you can describe your system's netlist in CppLink language and let CppLink perform the translation to C++ code.

Consider the following simple example:

ModuleSaw saw
net saw.amplitude <- sawamp
net saw.period <- sawper
net saw.out -> a
net 10.0 -> sawamp
net 25.0 -> sawper

ModuleSin sin
net sin.amplitude <- sinamp
net sin.period <- sinper
net sin.out -> b
net 10.0 -> sinamp
net 10.0 -> sinper

ModuleSum<REAL> sum
net sum.in1 <- a
net sum.in2 <- b
net sum.out -> out

This example instantiates three data-transformation boxes - one saw generator with a period of 25 ticks and amplitude 10 and a sine wave generator with amplitude 10 and a period of 10 ticks. Output signal of these generators is then combined together.

Issuing cpplink examples.cpplink output.cpp --steps=200 --interface=csv --watch=a,b,out translates the netlist into C++ code that performs simulation of 200 steps of this system and produces CSV table output with values of nets a, b and out on stdout. The produced code has to be translated with C++11 standard.

Issuing cpplink examples.cpplink output.cpp --steps=-1 produces C++ code that has no output and simulates an infinite number of system steps. This code is not meant to be run, however it can be verified using any verification tool that accepts C++ as an input language.

There are several options user can specify when translating netlist into C++ code:

• By-default produced code is self-contained (CppLink library is embedded into the source code). This produces quite large output files. If CppLink is installed and correct include paths to CppLink libraries are present, --uselib flag produces code without embedded library.

• There are three supported output interfaces. These interfaces can be specified using the --interface=<type> flag.

  • csv - simple CSV output format with quoted strings

  • excel - CSV output with MS Excel-specific dialect

  • plain - tab-separated columns. This format is suitable e.g. for GNUplot.

• To specify which columns should be output in the type, a comma-separated list of net names can be specified using --watch=<columns>.

To build CppLink you need Bison, Flex, Cmake >= 2.8 and Clang >= 3.6. Run mkdir build; cd build; cmake ..; make to compile CppLink. CppLink translator binary is located in build directory.

Input language is easy - there are only three types of commands; module instantiation, connect pin to net and connect constant value to net. Every command has to be on a separate line. When # appears, everything to the end of line is considered as a comment.

To instantiate module of ModuleType with name InstanceName, write ModuleType InstanceName or ModuleType<Arguments> InstanceName when the module features template arguments. For list of available module types and their arguments, see our documentation.

Each module instance features several input and output pins, whose description can be found in documentation. To connect an output pin to a net, write net module.pin -> NetName, to connect an input pin, write net module.pin <- NetName. Also constants can be connected to a net instead of an output pin - e.g. net 10.0 -> NetName. There can be at most one output pin connected to a net. Number of input pins is unlimited.

Developed by Zuzana Baranová and Jan Mrázek as a project in PB173 class at FI MUNI.