RubyNDS

Write DSi Homebrew apps in pure Ruby!

Documentation and setup at DOCS.md

RubyNDS is an SDK which includes an embedded mruby runtime, thin bindings to native DS libraries, build tooling and examples. There is both a low-level Ruby API for finer-grained control without C, and an idiomatic high-level Ruby API for developer happiness. The focus is DSi development, but inherently most RubyNDS applications will run on DS/2DS/3DS as well.

These 3 scripts all do the same thing.

• Connect to wifi
• Fetch some data
• Display the result through the libnds on-screen console (unparsed)

Here's the scary C example:

// This specific example is generated.
// Please read "What's the purpose?" in this README to understand why.
Wifi_InitDefault(WFC_CONNECT);

struct hostent *host = gethostbyname("wttr.in");
int sock = socket(AF_INET, SOCK_STREAM, 0);

struct sockaddr_in server = { 0 };
server.sin_family = AF_INET;
server.sin_port = htons(80);
memcpy(&server.sin_addr, host->h_addr_list[0], 4);

connect(sock, (struct sockaddr *)&server, sizeof server);

char request[] =
  "GET /NewYork?format=3 HTTP/1.1\r\n"
  "Host: wttr.in\r\n"
  "Connection: close\r\n\r\n";

send(sock, request, strlen(request), 0);

char response[512];
int bytes;
while ((bytes = recv(sock, response, sizeof response, 0)) > 0)
  printf("%.*s", bytes, response);

closesocket(sock);

Then that same example using the low-level Ruby API:

Net.wifi

sock = Net.connect("wttr.in", 80)

request_lines = [
  "GET #{PATH} HTTP/1.1",
  "Host: #{HOST}",
  "User-Agent: curl/8.0",
  "Connection: close"
]
request = request_lines.join("\r\n") + "\r\n\r\n"

Net.send(sock, request)

loop do
  chunk = Net.recv(sock, 512)
  break if chunk == ""
  print chunk
end

Net.close(sock)

Then again using the beautiful high-level Ruby API:

puts HTTP.get("wttr.in/NewYork?format=3") # Response has header auto-trimmed

See more low-level and high-level Ruby-only examples in examples

I wanted to write homebrew apps for the DSi using a favorable language. And since I don't really know any C, I wanted to avoid having an LLM create an entire framework for me. Not only is that pretty lame, but I learn nothing in the process as the majority of the hard work is done.

So the goal is that the C layer only exists as primitive bindings to a small-ish low-level Ruby API, which I've attempted to design myself, but haven't written myself since it's obviously in a language I don't know. The high-level Ruby API is a conglomeration of mrbgems that wrap one or more low-level Ruby API calls into much more idiomatic Ruby methods. Fortunately for me, that is pure Ruby that I get to write! (trust me, you can tell.)

For full transparency sake. I am crudely punching above my weight with this project. What I thought was going to be some tiny bindings to allow me to write small homebrew projects turned into a full SDK. I'm researching and learning on the fly, so be aware that many concepts and implementations will not be strong. I am merely a hobbiest Ruby programmer 🥀

That being said. This is only possible thanks to all of the DS native libraries and SDK components available like libnds, DSWiFi, Maxmod. And obviously devkitPro for even providing the cross-compilation tools and whatnot in the first place.

Thank you for reading.

RubyNDS is built on the work of many open-source projects:

• mruby and its contributors for the embedded Ruby runtime.
• devkitPro and its contributors for the toolchain and DS development ecosystem, including libnds, DSWifi, Maxmod, Calico, and libfat.
• Ariya Hidayat for FastLZ, used by R15V video.
• Thomas Pornin for BearSSL, used for on-device TLS and HTTPS.
• Larry Bank / BitBank Software for JPEGDEC, used for JPEG and MJPEG decoding.
• PacketVideo for the OpenCORE MP3 decoder, used for MP3 decoding.

All third-party components remain the property of their respective authors and are distributed under their respective licenses.

Although RubyNDS is available under the MIT License, it would be greatly appreciated, and highly encouraged if you could please contribute to this repository!

Also, you don't have to, but if you use RubyNDS for anything, please let me know! I'd love to see. 🙂