A leap year check in three instructions

I suspect most IOT device manufacturers expect/design their device to be landfill before worrying about leap year math. (In my least optimistic moments, I suspect some of them may intentionally implement known broken algorithms that make their eWaste stop working correctly at some point in the near future that's statistically likely to bear beyond the warranty period.)

"Is year divisible by four" will work perfectly fine for the next 75 years. Random consumer devices are definitely not going to survive that long, so being capable of dealing with it adds exactly zero value to the product.

It's hard to imagine being in a situation where the cost of the additional "year divisible by 100" check, or even the "year divisible by 400" check is too much to bear, and it's trivial enough that the developer overhead is negligible, but you never know when you need those extra handful of bytes of memory I guess...

> but you never know when you need those extra handful of bytes of memory I guess...

I guess on all those crappiest of 32 bit devices with 2.6 based kernels (which are practically unupgradeable due to vendor patches[1]) which will never make it to 2100 to the "year divisible by 100" check, because their time_t overflows in 2038.

On the plus side, that overflow turns the date into 1901, so perhaps they won't actually blow up due to leapyear bugs for another couple of years? That'll be a fun vintage computing archeological bug fix for someone.

[1] I am at least partly responsible for one of these products from a failed hardware startup I work at in 2012/13.