Disc Spin-Off Channel Development Environment: Description

Introduction

The Revolution SDK Disc Spin-Off Channel Development Environment package is the development environment for disc spin-off channels and channel installer applications. Use this package to create applications that use a disc spin-off channel.

A disc spin-off channel is the name for a certain kind of NAND application that is installed in the Wii console NAND memory by a disc application and, once installed, can be started from the Wii Menu. By using a disc spin-off channel, you can provide the features of an application without the need to insert the application's disc into the Wii.

Disc Spin-Off Channel Development Environment Package

1. Channel Installation API

This API provides functions for checking whether installation is possible and for executing the installer. It is provided as part of the features of the OS.

2. Disc Application Startup API

This API provides functions for executing disc applications. It is provided as part of the features of the OS. A disc recognition sequence is generated when the disc application is executed, so an error-handling process needs to be implemented. With this API, you can pass arguments and LaunchCode to the application at startup.

3. Tools

In addition to the tools necessary for developing channel installer applications, tools that are designed to support the development process are also provided.

4. Sample Demos

Simple sample demos have been prepared that use the Channel Installation API and the Disc Application Startup API. There is also a procedure here that uses the demos to show an example of how to develop a simple channel installer application.

The title-id of Disc Spin-Off Channels

A disc spin-off channel must be created as a NAND application with the same title-id as the disc application. When a disc spin-off channel is created, the value of 00010004 is assigned to <title-id (Hi)> for both the disc application and the disc spin-off channel. By specifying 4 as the value of the setpcode argument in the disc application, the value -pc 0x4 is specified for the makeWad argument in the NAND application.

Application DLF files

When normal disc applications are being developed, each DLF (disk layout file) file corresponds to a single application. However, when developing applications that use disc spin-off channels, you need to create one application DLF file and one installer DLF file and then use this pair of files to create the application's ultimate DLF file.

You can develop these DLF files separately, just as long as the installed channel information is in sync.

Launching the Channel Installer

Launching the channel installer with OSLaunchInstaller transfers all control over the application to the channel installer. After the installation sequence has completed, the channel installer reloads the application and jumps to the start of the application.

If OSGetResetCode returns the value OS_RESETCODE_INSTALLER when the application starts, the process has returned from the channel installer. At this time, you can use OSGetLaunchCode to get the launch code that was passed when the channel installer was launched.

Once the process has returned from the channel installer, use OSGetReturnCode to get the error information. Below is a list of the return codes that can be returned from the channel installer.

(Note: These codes are not returned except when OSLaunchInstaller has been called. If they occur at any other time, treat it as a fatal error.)

Return Values	Description
`OSINSTALL_RETURN_OK`	Ended successfully
`OSINSTALL_RETURN_INVALID`	Invalid argument at launch
`OSINSTALL_RETURN_INIT_FAILED`	Installer failed to initialize
`OSINSTALL_RETURN_NOEXISTS`	Could not find the data on the disc that was supposed to be installed
`OSINSTALL_RETURN_EXISTS`	Specified channel has already been installed
`OSINSTALL_RETURN_MAXBLOCKS`	No free space in system
`OSINSTALL_RETURN_MAXFILES`	Could not create file in system
`OSINSTALL_RETURN_MAXCHANNELS`	No free channels
`OSINSTALL_RETURN_IMPORT_FAILED`	Installation failed
`OSINSTALL_RETURN_UNKNOWN`	Unknown error code
`OSINSTALL_RETURN_FATAL_ERROR`	Error code for program design error

Current Limitations and Cautions

Disc Spin-Off Channels

Make sure that the firmware version being used for disc spin-off channels is the same as the firmware version being used by the application.

Channel Installer

The channel installer does not operate correctly if the Wii Menu or version 1.14 or later of the DEVKIT system menu has never been installed. (When this is the case, OSCheckInstall returns -1 and ends on an error.)
Also, if you repeatedly install and delete channels while the Wii Menu is not installed, the system's channel information becomes disarranged (for example, causing OSCheckInstall to fail even though there are free channels). To prevent this from happening, periodically install the Wii Menu.
Up to 16 channels can be installed at the same time. Due to guideline restrictions, a disc application can install only one disc spin-off channel.
The channel installer does not use the version of firmware being used by the game application. Rather, it uses the 33 system firmware. If the 33 system firmware is not installed, the installer will fail to run.

Launch Restriction

Only applications with the same company code can be launched.

Guideline Restrictions

There are a number of guideline restrictions concerning the development of disc spin-off channels. For details, read the Programming Guidelines Disc Spin-Off Channel Edition.

Revision History

2009/12/21 Added precaution about the firmware used by disc spin-off channels.
2009/10/13 Added precaution about the firmware used by the installer.
2009/01/09 Deleted precautions relating to terminology.
2008/12/26 Revised some terminology.
2008/11/18 Made revisions.
2008/10/29 Initial version.

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