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zava

Mini Java VM in Zig v0.13.0

What it is

Zava is a Java^* VM implementation in Zig. This is a sister project of Gava which is using Go. The goal of Zava is to implement a couple of features which are not capable of doing by Go, such as GC and fine control of memory allocation.

The reference of the implement is JVM Spec 8 edition and it is supposed to be compatible with Java 8 bytecode.

* JAVA is a trademark of Oracle America, Inc.

Roadmap

Feature:

• type system definition
• class file parser
• instructions interpretion
• native methods bridge to support HelloWorld
• class loading
  • bootstrap class loader
  • user defined class loader
• string pool
• basic reflection support (Class, Field, Method, Consutructor)
• multi-thread and concurrency
• garbage collector
• profiling and Debugger integration

Non-functional:

• sufficent unit test coverage
• code readability and clear documentation of high-level design
• mini ebook to describe how to evolve a mini VM from scratch
• VSCode debugging extension

Get started

Download JDK and extract to jdk folder. The default class path is examples/classes and jdk/classes, so any classes located in the path can be loaded by zava.

• HelloWorld

zig build

./zava HelloWorld

Debugging

A VS code launch.json is configured for your debugging.

And after running the program, a zava.log is produced to trace the execution.

• info level: only method calls are logged
• debug level: per instruction executions are also logged with the context