Memory Management Fun

Flash?

There comes a time in every programmer's life when they ask themselves, "how much memory is my code using?" Now is that time.

Background: what are we doing?

Being a first aid kid addon, the logical addition to our product is a way for people to find out first aid information in order to help people in trouble. So, of course, we decided to go and make essentially a new operating system for the Photon to run off of. What could go wrong?

C++ is Fun (this is a lie)

Though it's quite widely known and I do have a bit of experience, C++ still posed quite a few challenges in programming. To put it bluntly, I'm still working on it. The inclusion of libraries and a lot of other factors have made this project quite a bit more complicated than I would have liked, but this is the life that I've chosen.

Crashing and Memory Management

The Photon and its firmware are both quite fickle, and the slightest perturbation has caused countless crashes in our testing. Code that works fine one moment crashes the next, sometimes without any changes, though rarely in such a case. Much more common is random crashing caused by removal of code that has nothing to do with the cause of the crash!

When I was first prototyping the code, I decided to include an abbreviation field to store a menu's abbreviation. But I never used this field, and so I believed that I could free up some critical space by getting rid of this space. No dice, however, as the program crashed as soon as I pressed any buttons. No debug output could explain it; and at this point this memory-eating feature still exists.

Another fun bug came with changing the information that our device provided. I noticed that some characters were being cut off, so I decided to fix it in my code. And again, it just decided to crash randomly?

This issue is very confusing, and the only explanation I possibly have is that the method of allocating memory within the code is not allocating enough. After all, I am using an array of char pointer pointers as a 2 dimensional array, so I do not know the specifics of how the Photon manages its memory. Thus, attempting to read the memory at a certain point may exceed the bounds of the array and read other information that is complete gibberish.

But it this were the case, there still remains a puzzling bug. The location menu currently has no functionality built into its center button. In the final product, pressing the center button should call the Geolocation methods we worked so tediously on before and then display the results to the screen. But right now, we are still prototyping this "Operating System" so that functionality is not included. Despite this, pressing the button appears to be a toggle of some sort. Specifically, toggling whether some gibberish appears on the menu or not. We added tracing calls to see whether some other subclasses' method was being called instead, but it was not. The code within the method itself is just the tracing output.

Color me surprised. These random crashes happen for no apparent reason, either. It's quite frustrating trying to develop in such an environment. Perhaps it would be better to try and develop something similar for a computer instead, just to try and flesh out the concept.