Playdate-C++

for SDK version 2.0.3, but attempts will be made to keep this up to date

You want to use C++ on the playdate! Great, except you keep getting linker errors about exception handling, and your global variables aren't getting initialized properly, and __attribute__((constructor)) isn't helping, and...

Prerequisites

1. CMake
2. A compiler capable of handling C++20 (Only a concern for the simulator, the arm-none-eabi compiler referenced by prerequisites section from "Inside Playdate With C" supports this.)
3. For the Playdate hardware, you need to have the ARM toolchain of version 12.3.rel1 or later. If you don't you may encounter linker errors.
4. The Playdate SDK installed (and preferably added to the PATH)
5. The forward declaration of eventHandler in pd_api.h needs to be deleted or commented out. At time of writing, this is lines 58-61, there is also a comment indicating that is the main entry point function. This will not impact pure C builds, including the builds of all the Playdate examples. Not doing this will lead to linker errors, if you're seeing errors like "linkage specification contradicts earlier specification for 'eventHandler'", you did not remove this forward declaration.

How to use

Project Setup:

Follow along with the CMakeLists.txt file in the "Hello World" example:

1. Add this repo as a subdirectory of your project.
2. Use the add_subdirectory directive to include this package in your project
3. Use the add_playdate_application directive with your source to add your application to the build

Follow along with the main.cpp file in the "Hello World" example:

1. Surround the eventHandler function with and extern C statement to ensure correct linkage.
2. call eventHandler_pdnewlib first thing in your eventHandler

Building

This uses the CMake build system, which is fully cross-platform. Many IDEs like CLion and VSCode either integrate directly with CMake, or provide extensions which do so. Otherwise, refer to the documentation from CMake for the recommended process for building on your platform from the command line or CMake GUI.

To build for the playdate hardware

A toolchain file needs to be specified. This can be done in the CMake options field in a build configuration in CLion, or from the command line, with the following option:

-DCMAKE_TOOLCHAIN_FILE=<path_to_playdate_SDK>/C_API/buildsupport/arm.cmake

To build the examples

Same as the toolchain file, this is achieved with an option passed to CMake:

-DPDCPP_BUILD_EXAMPLES=ON

Building other libraries for the playdate

Ok, so now you can write your project in C++, so you want to link in that one library that makes your life super easy. Everything works in the simulator, you build for the hardware, boot it up and... Everything crashes; no error logs.

You can try this:

...
modify_target_for_playdate(the_library_that_does_the_thing_you_need)
...
target_link_libraries(my_project pdcpp the_library_that_does_the_thing_you_need)

The CMake function modify_target_for_playdate sets a handful of attributes on any CMake target in the project that are required for operation on the Playdate.

This function works for libraries which:

• are compiled from source by your project
• don't link in other libraries that haven't been modified for playdate.
• are reasonably platform-agnostic
• either don't throw exceptions, or provide options for disabling exceptions. (we're working on the exceptions thing, and would really rather support them.)

Caveat Emptor

The modify_target_for_playdate function alone may not be enough.

If the library expects a certain type of hardware, or does anything that expects there to be a traditional operating system backing it up (threads, file systems, networking, etc.) nothing about this build-system trickery will save it.

The best advice here is to test with the Playdate hardware early and often. The simulator can't sandbox the OS, so you will not see certain classes of errors until trying to run on the hardware. You will be far happier if you catch those failures without writing a bunch of code that won't work on the target.

This doesn't work for me

The base principles of this are explained on this forum thread. Good luck.

This doesn't work at all

Yikes!?‽!? Please submit a bug report to NaOH#1432 or MrBZapp on discord, or if you're able, a please submit pull request with a fix :) :)