showNumber() function uses abs() instead of labs() for long variables

[KelevraSlevin7]

When trying to display a number bigger than 32.767 it overflows because the used abs() function returns an int and not long. When abs() is changed to labs() the function is working as intended.

Or I did something wrong handling the function and didnt realize it...

[jasonacox]

Great find @KelevraSlevin7 ! I was confused as to why you were seeing this but I wasn't. I use an Uno for testing. I remember testing for overflow on the Uno and didn't see a problem. It turns out that Arduino uses this macro for their device core:

#define abs(x) ((x)>0?(x):-(x))

Which works with any type. Of course, that isn't standard for C and there is no macro for ESP or other MCUs. To test, I added #undef abs to the top of TM1637TinyDisplay6.cpp which causes it to default to the C library abs(). I saw the error with the int overflow occuring.

In any case, you are right. We need to switch to labs() or we could add the override macro to TM1637TinyDisplay6.cpp.

[jasonacox]

I see you have submitted PR #33

[jasonacox]

We need to apply the same change to the 4-digit display (TM1637TinyDisplay.cpp). For the most part, the 4-digit display which can only render up to 9,999 would not see this and would overflow (show ----) above the digit capacity. However, if you send display.showNumber(66000) you will get 464 in the display (the overflow above the max unsigned int 65,536).

[jasonacox]

Actually, as I test this, the labs() function call adds about 16 bytes to the progmem, likely due to the C library function call overhead. The use of abs() in the display calculations are simple and aren't stacking so a macro would work fine. I'm going to override the labs() function with a macro at the top of the cpp files and see if everything still works.

#define labs(x) ((x)>0?(x):-(x))

Note: I'm not putting the macro in the header files so it won't override the users calls to labs().

[KelevraSlevin7]

Ah yeah didnt think about the added overhead of the labs() function. Thanks for the fast response and change of the code.