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 have 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
  • Defragmentation
  • 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.

First, ensure submodules are installed with:

git submodule update --init --recursive

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
• jvsTSX

Collaborators

• Andrew Apperley
• Patrick Kowalik
• Walter Tetzner
• Tulio Goncalves
• Kresna Susila
• Sam Hellawell

Special Thanks

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