Developers: How to Build System and Core Plugins

Getting Started

You will need the latest Xcode (4.2 or greater) running on OS X 10.7 to build OpenEmu.

About OpenEmu

The goal of OpenEmu is to be system agnostic so that plugins can be created to add support for new systems.

OpenEmu can be described as three layers:

1. The Application handles audio and video output to the OS and input from HID devices.
2. The System Plugin describes a system and provides an interface for cores to plug into.
3. The Core Plugin is the implementation of the emulator which then ties into a system plugin.

System Plugins

Overview

System Plugins describe a core system and contain:

• SystemController and SystemResponder classes
• Plugin name and system identifier
• Supported rom types (file suffixes)
• Button mapping defaults and settings
• Controller preference layouts, graphics and icons.

These settings are stored in property list (.plist) files.

Structure of a System Plugin

Once compiled, system plugins take on the Product Name of the core they were built for if a target is set in the OpenEmu project. They are stored in ~/Library/Application Support/OpenEmu/Systems/

For example: Genesis.oesystemplugin, NES.oesystemplugin, SuperNES.oesystemplugin, etc.

The contents of the system plugin bundle include the compiled SystemController and SystemResponder classes, the .plists and supporting files for controller preference graphics and icons.

How to build a System Plugin

OpenEmu includes plugins for several systems. In this example, we will create a new system plugin for the TurboGrafx-16/PC Engine.

Our first step will be adding a new Target to the OpenEmu project. Choose the Bundle template under Framework & Library for Mac OS X and then give it a Product Name.

Once created, you will then have to add some custom OE-related values to the info plist. These will include, OEArchiveIDs, OEControlListKey, OEFileSuffixes, Principal Class, OESystemIcon, OESystemPluginName and OESystemIdentifier.

Since all plugins follow the same structure, we can duplicate a set from another system and then edit accordingly.

NSString *OEPCEButtonNameTable[] =
{
    @"OEPCEButton1",
    @"OEPCEButton2",
    @"OEPCEButtonUp",
    @"OEPCEButtonDown",
    @"OEPCEButtonLeft",
    @"OEPCEButtonRight",
    @"OEPCEButtonRun",
    @"OEPCEButtonSelect"
};

How to use a System Plugin

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Core Plugins

Overview

Core Plugins implement systems and contain: ...

Structure of a Core Plugin

oecoreplugin, SystemResponderClient.h, GameCore.h, GameCore.mm ...

How to build a Core Plugin

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How to use a Core Plugin

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