libElysianVMU

C17-Based Library for emulating the Sega Dreamcast's Visual Memory Unit
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Accurate · Full-Featured · Cross-Platform

Overview

libElysianVMU (libEVMU) is a standalone emulator core of the Sega Dreamcast's 8-bit Visual Memory Unit (VMU), written in C17. It is the core powering the ElysianVMU emulator for Windows, MacOS, and Linux, which has been separated from any platform-specific back-end or UI front-end. Several years of meticulous research and reverse engineering has gone into the creation of this core, which has now been open-sourced in hopes of benefitting the Dreamcast community at-large.

Goals

The primary goal of libEVMU is to provide a one-stop, all-encompassing framework exposing everything the VMU has to offer in a standard C codebase that can be ported to any platform or wrapped to any language, allowing for everyone to use it in their projects and to benefit from a common codebase. At a high-level, this goal encompasses:

Fully and accurately emulating the VMU as a standalone gaming device
Providing tooling and APIs around its filesystem and all relevant file formats
Meticulously documenting every aspect of the codebase to expose everything that was previously undiscovered
Being performant enough to be ported to a Sega Saturn, N64, or toaster oven
Offering a high-level entity/component-based API that is intuitive and easy to work with
Allowing for modeling exotic, customized, nonstandard VMUs with extended volumes or capabilities
Providing low-level hooks for supporting debuggers and high-level tooling
Rigorously unit testing all aspects of the codebase to ensure correctness

Features

Battery
- Emulated low-voltage signal
BIOS Support
- Official (US and Japanese)
  - Skip directly to GAME
  - Modify date/time
- Emulated Software back-end
Buzzer
- Creates and manages PCM buffers for audio back-end
File System
- Import + export files
- Formatting
- Dragmentation
- Unlock/lock extra flash blocks
- Diagnostics and validation
- Changing volume icons or color
- Loading custom ICONDATA
- Modifying copy protection bits
- Loading a GAME file from only a VMS and no VMI
- Recalculating checksums
- Extracting and texturing icons
- Extracting and texturing eyecatches
- Supported File Formats
  - .VMI
  - .VMS
  - .DCI
  - .DCM
  - .flash
  - .bin
Gamepad
- Polling or event-driven input back-ends
- Supports turbo buttons, slow motion, and fast-forward
LCD Screen
- Emulated pixel ghosting and grayscale effects
- Extra options for bilinear filtering, color inversion, etc
- Provides a simple virtual framebuffer abstraction for renderer back-end
- Provides asynchronous screen refresh callbacks, only when contents change

Platforms

libEVMU is being actively tested in CI on the following targets:

Windows
MacOS
Linux
Sega Dreamcast
Sony PSVita
WebAssembly
iOS
Android

Compilers

libEVMU is being built in CI with the following compilers:

GCC
Clang
MinGW-w64
Emscripten

NOTE: Microsoft Visual Studio support is currently a work in progress!

Building

Building is done with standard CMake. You should be able to open CMakeLists.txt directly as a project file in most IDEs such as XCode, Qt Creator, CLion, etc if you wish to build from a UI.

To build the project and its unit tests from the command-line, you can do the following:

mkdir build
cd build
cmake -DEVMU_ENABLE_TESTS=ON ..
cmake --build .

Credits

Author

Falco Girgis

Contributors

Colton Pawielski

Collaborators

Andrew Apperley
Patrick Kowalik
Walter Tetzner
jvsTSX
Tulio Goncalves
Kresna Susila

Special Thanks

Marcus Comstedt
Shirobon
Deunan Knute
Dmitry Grinberg
RinMaru
UltimaNumber
Joseph-Eugene Winzer

cykoder / libevmu