Free virtual machine software for linux

C# Java Virtual Machine is a tiny implementation of the Java VM, including simple native classes. This project is written using the C# language. The VM is very easily expandable by writing additional native or Java classes.
Enhancements:
- The DbConnection class, which provides a connection to MS SQL or PostgreSQL using ADO.NET, was added.
- The Syst.MachineName method, which returns the machine name, was added.
- String.startsWith and String.endsWith functions were added.
- Some comments for VM.cs were written.

High Level Virtual Machine is a toolkit for developing virtual machines for dynamic languages.
The High Level Virtual Machine is:
- Based on LLVM (Low Level Virtual Machine). LLVM is HLVMs sister project. HLVM gains tremendous capability from LLVM in the areas of code generation, bytecode storage, runtime execution, etc.
- Aimed at supporting dynamic languages such as Ruby, Python, Perl, Jython, Haskell, Prolog, etc.
- A complete compiler developers toolkit for creating new languages easily. To write a new compiler, language designers simply write a plugin that describes the language to HLVM and how to translate the grammar productions into HLVMs comprehensive Abstract Syntax Tree (AST). After that, HLVM handles all aspects of code generation, bytecode storage, XML translation, JIT execution or interpretation, and native compilation.
- A language interoperability framework. Because all front end compilers generate code in the same AST, they can interoperate. Use of the runtime library for common constructs (e.g. "string") allow even complex data types to be shared between languages. Users of HLVM can write complex programs in multiple languages and be assured the result can be executed efficiently.
- A code management system including code revisioning, interface versioning, automated recompilation, separation of workspaces, etc.
- Currently under development. Project started April 20th, 2006. Stay tuned to this web site for future developments.

Joeq is a virtual machine and compiler infrastructure designed to facilitate research in virtual machine technologies such as Just-In-Time and Ahead-Of-Time compilation, advanced garbage collection techniques, distributed computation, sophisticated scheduling algorithms, and advanced run time techniques.
Joeq is entirely implemented in Java, leading to reliability, portability, maintainability, and efficiency. It is also language-independent, so code from any supported language can be seamlessly compiled, linked, and executed -- all dynamically.
Each component of the virtual machine is written to be independent with a general but well-defined interface, making it easy to experiment with new ideas.
Joeq is released as open source software, and is being used as a framework by researchers on five continents on topics ranging from automatic distributed virtual machines to whole-program pointer analysis.
Joeq is a virtual machine and compiler infrastructure designed to be a platform for research in compilation and virtual machine technologies. We had three main goals in designing the system. First and foremost, we wanted the system to be flexible. We are interested in a variety of compiler and virtual machine research topics, and we wanted a system that would not be specific to researching a particular area.
For example, we have interest in both static and dynamic compilation techniques, and in both type-safe and unsafe languages. We wanted a system that would be as open and general as possible, without sacrificing usability or performance.
Second, we wanted the system to be easy to experiment with. As its primary focus is research, it should be straightforward to prototype new ideas in the framework. With this in mind, we tried to make the system as modular as possible, so that each component is easily replaceable. Learning from our experience with Jalapeno, another virtual machine written in Java, we decided to implement the entire system in Java.
This makes it easy to quickly implement and prototype new ideas, and features like garbage collection and exception tracebacks ease debugging and improve productivity. Java, being a dynamic language, is also a good consumer for many of our dynamic compilation techniques; the fact that our dynamic compiler can compile the code of the virtual machine itself means that it can dynamically optimize the virtual machine code with respect to the application that is running on it. Javas object-oriented nature also facilitates modularity of the design and implementation.
Third, we wanted the system to be useful to a wide audience. The fact that the system is written in Java means that much of the system can be used on any platform that has an implementation of a Java virtual machine. The fact that Joeq supports popular input languages like Java, C, C++, Fortran, and even x86 binary code increases the scope of input programs. We released the system on the SourceForge web site as open source under the Library GNU Public License.
It has been picked up by researchers on five continents for various purposes, among them: automatic extraction of component interfaces, static whole-program pointer analysis, context-sensitive call graph construction, automatic distributed computation, versioned type systems for operating systems, sophisticated profiling of applications, advanced dynamic compilation techniques, system checkpointing, anomaly detection, secure execution platforms and autonomous systems. In addition, Joeq is now used as the basis of the Advanced Compilation Techniques class taught at Stanford University.
Joeq supports two modes of operation: native execution and hosted execution. In native execution, the Joeq code runs directly on the hardware. It uses its own run-time routines, thread package, garbage collector, etc. In hosted execution, the Joeq code runs on top of another virtual machine. Operations to access objects are translated into calls into the reflection library of the host virtual machine.
The user code that executes is identical, and only a small amount of functionality involving unsafe operations is not available when running in hosted execution mode. Hosted execution is useful for debugging purposes and when the underlying machine architecture is not yet directly supported by Joeq. We also use hosted execution mode to bootstrap the system and perform checkpointing, a technique for optimizing application startup times.
Joeq system consists of seven major parts:
- Front-end: Handles the loading and parsing of input files, such as Java class files, SUIF files, and binary object files.
- Compiler: A framework for performing analyses and optimizations on code. This includes the intermediate representation (IR) of our compiler.
- Back-end: Converts the compilers intermediate representation into native, executable code. This code can be output to an object file or written into memory to be executed. In addition, it generates metadata about the generated code, such as garbage collection maps and exception handling information.
- Interpreter: Directly interprets the various forms of compiler intermediate representations.
- Memory Manager: Organizes and manages memory. Joeq supports both explicitly-managed and garbage-collected memory.
- Dynamic: Provides profile data to the code analysis and optimization component, makes compilation policy decisions, and drives the dynamic compiler.
- Run-time Support: Provides runtime support for introspection, thread scheduling, synchronization, exception handling, interfacing to external code, and language-specific features such as dynamic type checking.

Parrot is a virtual machine designed from scratch to support dynamic languages, including Perl 6, Perl 5, Python, Ruby, Tcl, and many others. Parrot was born from the Perl 6 development effort, but currently treats Perl 6 as only one of its many client languages.

Virtual Drum Machine is a simple drum machine.
It works for little endian/linux kind of machines. You may let it work on others machines, but you probably will get troubles with it.
You definitely need oss (or maybe alsa) for sound output, and a posix-like operating system. To let it work on a big endian machine should be painful.
You write a rhythm, then you compile it, then you are able to play it to your sound card or save it to a file.
The Virtual Drum Machine is made of
- the Rhythm Compiler,
- the runtime library.
The Virtual Drum Machine is in the public domain. Who needs a license? money makers? Protection against robbery? let me laugh... Read any text of law, you will see where the robbers reside.
A simple file would look like :
void main_rhythm(void)
{
tempo = 120;
- a
. b
. b
.
- a
.b
- a
.
. b
. b
- a c
. b
}
Install:
Do a "./configure" in the drums directory, then "make", then "make install", it should be alright. You can listen to some examples in the examples/ directory.
Who yo use it?
Write a rhythm. Compile it with "rc". Run the produced program. You are done.
See the examples/ directory to get the point.
When you run an example, try "-h" to get the available options.
It should be self-explanatory.
The rhythm compiler has several options. By running "rc --help", all should be clear.
Technical Details:
The compiler will parse the input file line by line.
If a line starts with "*" or "." (not counting leading white spaces), the whole line is seen as a rhythm line, and is transformed into C code. If not, it is passed as is to the C file.
Beware! You MUST NOT start any C code line by "*" or "."!
You can create as much functions as you want, write any C code you want. But remember that a line starting by "*" or "." is seen as a rhythm line and is translated by "rc" into C code.
You must provide a "void main_rhythm(void)" function, that will be called by the library. It is the starting point of your rhythm. It can be "void main_rhythm(int argc, char *argv[])" too, with common meaning for those parameters (non-C coders will have trouble with the Virtual Drum Machine).
You can change the tempo (ex. "tempo=100;") or the volume (ex "vol=0.4;") at any time. Each sample comes with its own volume and panning (ex. "a.vol = 0.1;" "a.pan=-0.8;"). Volumes range from 0 to what you want. 1 is for the normal volume. Panning ranges from -1 (left) to 1 (right). 0 is center. All values are double. You can use "volume" instead of "vol", and "panning" instead of "pan". There is no global panning, if you want all left, set all samples to left.
To run in stereo mode, dont forget "-s" when running the generated program. It is mono by default.
You absolutely need to compile and run the examples, and read them to get the point out of it!
The "rc.conf" file contains configuration informations. You specify the sample by "sample" followed by its name (the one you will use in your rhythm files), then the file that will be played. The name of the sample must start by a letter, followed by letters and/or numbers (it must be a valid C identifier, without "_" though). The configuration file contains the install directory, used by "rc" to compile your rhythms. Take a look at the one that is provided to see how to use it.
The sound files are simple wav files. They all should be of the same rate, which can be specified to the generated program, using the "-f" option (44100 is the default). (The library only handles very basic wav files, if yours dont work, you probably will have to modify the library for the program to handle it.)
When you add a sample, you must modify "rc.conf" for the changes to appear. The samples are hard-linked to the produced program, so if you change "sample a /some/dir/file1.wav" by "sample a /one/other/dir/file2.wav" in the configuration file, the previously generated programs will still use "/some/dir/file1.wav". You will have to compile them again to take the changes into account.
Enhancements:
- The code has been modified to let gcc 4 compile it.

The Java Brainfuck Compiler is a compiler for the uniquely powerful Brainfuck language, which produces Java bytecode that will run on any Java Virtual Machine (with no intermediate steps such as going by way of Java code).