Crunk-QRcode: Fast QRCodes from Lua (C-Accelerated)

SDK Development Discussion
1

Hey all!

I just published my first open-source Lua C-Extension: crunk-qrcode.

It takes an MIT licensed QRCode generator written in C (qrcodegen.c), tweaks it to compile for Playdate and provides a Lua wrapper. This is fast enough to do real-time QRCode generation (no async callbacks required). Speed-up is 75-150x over the playdate.graphics.generateQRCode in the SDK, depending on length:

Length Lua C Speedup
16 1050ms 7ms 150x
100 2267ms 21ms 100x
254 3934ms 46ms 85x
1323 16114ms 214ms 75x

Here's a stupid demo where I regenerated the qrcode in realitime via crank.
playdate-qrdemo

https://github.com/notpeter/crunk/tree/main/crunk/qrcode

9 Likes
2

I'd love to add that speed up! Hope to use it soon. Good job. Thx.

3

Looks like the colours are inverted, or is that okay? I don't seem to be able to scan it using Firefox on Android.

4

@thomastc Oops. That animated GIF is indeed inverted. It was from a pre-release version of the code.

Here's what the code in the repo produces:
qr

Also funny because iOS will happily read the inverted code.

1 Like
5

Ohhh nice, that's amazing. I was specifically for an option to set error recovery level to low, because we're showing it on a digital screen anyways, no need to protect against torn paper.