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libEVMU

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