flintvn/flintjvm

Purpose and entry points

Flint is a C++ embedded Java-like virtual machine with native bindings for core runtime APIs, graphics, networking, storage, and RTOS/platform services. The VM public surface and likely integration entry point are vm/inc/flint.h and vm/src/flint.cpp; platform adopters supply system implementations modeled by template/src/flint_system_api.cpp.

VM lifecycle and execution

The VM coordinates class loading, object/runtime state, threading, native dispatch, and bytecode execution. vm/src/flint_execution.cpp is the interpreter/execution core; vm/src/flint.cpp owns top-level VM behavior; vm/src/flint_java_thread.cpp represents managed Java threads. Execution crosses into platform and native layers through vm/src/flint_native_interface.cpp.

Class, bytecode, and archive loading

Class metadata is parsed and retained through class-loader, constant-pool, field, and method subsystems. vm/src/flint_class_loader.cpp, vm/src/flint_java_class.cpp, and vm/src/flint_const_pool.cpp form the class-definition path. Input may come from raw files or ZIP/JAR-like archives via vm/src/flint_file_reader.cpp and vm/src/flint_zip_file_reader.cpp, creating a boundary between application artifacts/storage and VM-internal representations.

Managed object model and runtime services

Objects, arrays, strings, throwables, and dictionaries provide the VM’s managed runtime substrate. Key implementations are vm/src/flint_java_object.cpp, vm/src/flint_array_object.cpp, and vm/src/flint_java_string.cpp. These structures are consumed by the interpreter and native-interface boundary, where native code must preserve VM object/reference conventions.

Native Java API implementation

Native methods implement the Java-facing base library in C++. Shared binding infrastructure is in native/common/src/flint_native.cpp and native/common/src/flint_native_common.cpp. Core native APIs—object/class behavior, strings, files, math, reflection, and threading—reside under native/base/src/flint_native_object.cpp, native/base/src/flint_native_string.cpp, and native/base/src/flint_native_thread.cpp.

Graphics and networking extensions

Optional native domains extend the runtime beyond base APIs. Software RGB565 graphics, fixed-point support, and Java graphics bindings are implemented by native/draw/src/flint_native_graphics.cpp, native/draw/src/flint_native_rgb565_graphics.cpp, and native/draw/src/flint_rgb565_sw_gfx.cpp. Socket, datagram, address, and stream bindings are implemented in native/net/src/flint_native_flint_socket_impl.cpp, native/net/src/flint_native_flint_datagram_socket_impl.cpp, and native/net/src/flint_native_flint_socket_input_stream.cpp.

Platform abstraction and deployed runtime

The VM depends on system API abstractions for OS/platform operations, configured through template/inc/flint_conf.h and implemented by adopters. The provided embedded deployment targets FreeRTOS, FatFs, and lwIP: impl/src/freertos_system_thread_api.cpp, impl/src/fatfs_system_io_api.cpp, and impl/src/lwip_system_net_api.cpp. Control flows from VM/native APIs to these adapters, isolating platform-specific scheduling, filesystem I/O, and network stacks from interpreter code.