Compressor

This app is a file compressor that runs on the NumWorks calculator. It allows you to compress your files on-calc, without needing a computer, with compression ratios around 2. It allows you to store twice the files you could have stored without!

How to use the app

When you open this app, you need to choose between two mode, which are complementary: compress and decompress

Compressing a file

To compress a file, press the 1 button on the calculator.

Then, you will find a file selector, just select the file you want to compress using the up and down keys before pressing OK or EXE.

If everything worked fine, the app should exit almost immediately. Otherwise, check the troubleshooting section.

If you want to access the compressed file again, read the next section to decompress it.

Decompressing

To compress a file, press the 2 button on the calculator.

Then, you will find a file selector, just select the file you want to decompress using the up and down keys before pressing OK or EXE. Your file will have the .pylz4 extension.

If everything worked fine, the app should exit almost immediately, and your file will be available again, as if it had never been compressed. Otherwise, check the troubleshooting section.

Download

You can download the Compressor app from this link:

Installation

To install the Compressor app, follow the instructions in the how to install guide.

Troubleshooting

Here are solutions to some common problems you can encounter with this app

Error: Storage is full

You don't have enough free space to store the new file. This should mainly happen when decompressing files. In this case, try to compress or delete other files before retrying.

This error also show required free space and current free space to help you to visualize how much memory you need to free.

Note that you can't delete compressed files without decompressing them for now without a computer, see #2.

Error: Couldn't write file

You don't have enough free space to store the new file. This should never happen as you would get Error: Storage is full instead. If you get this error, the file is definitely lost.

In this case, please open an issue to investigate this case.

Error: Output file already exists

This error means the output file is already created.

When compressing, it means you already have a compressed file with the same name. In this case, rename the file you want to compress from the Python app and retry.

When decompressing, it means you already have a decompressed file with the same name. In this case, rename the already exiting file from the Python app and retry.

Error: Compression/Decompression failed

This error shouldn't happen in most case.

If you get this error during compressing, it means the compressed file is more than 10 bytes bigger than the source file, in which case compressing the file is useless anyway.

If you get this error during decompressing, it means that your uncompressed file is bigger than 60KB, bigger than the current storage size on locked NumWorks.

This error can also means that the compressed file is invalid, which shouldn't happen unless you are editing the file using another way. When I'm writing this app, no such tool exist without a computer so it shouldn't be a problem.

Compressing other files than Python

Compressing other files than Python scripts is not implemented as there would be near-zero benefit to it.

Here are the files present on the NumWorks:

  • Internal files (settings, calculation variables, functions, equations…) which are often useful and lightweight, and wouldn't benefit much from compression
  • Emulator saves, which are already compressed by default using the same algorithm as this app
  • KhiCAS sessions, not implemented as not really widespread, with most people only using one session, which would need to be compressed/decompressed on each KhiCAS launch. It would better be implemented internally to KhiCAS, like emulators saves

We also need to keep the file list clean for easy navigation.

Access from computer

To manage compressed files from a computer, you can use any tool that can display the calculator files, including non-Python ones, like

  • Upsilon Workshop (only removing and rename, no compressed file downloading)
  • NumWorks Connector, handling everything, including rename, deletion, backup and uploading without any account

Note that, for now, none of these tools allow transparent decompression.

Compressed files should be decompressibles using LZ4 on a computer, but I didn't actually test.

Source code

Source code for Compressor is available here.