I can explain this a bit more, it's not that hard once you get the hang of it.
This code does exactly the same thing as your code, it's just shorter.
return PREMIUM_TIMER_ENABLE != 0;
PREMIUM_TIMER_ENABLE equals to a number value, most likely this will
only be 0 or 1.
So let's say that PREMIUM_TIMER_ENABLE = 0.
According to your original code, 0 means false.
This is also exactly what 'PREMIUM_TIMER_ENABLE != 0' does.
if (PREMIUM_TIMER_ENABLE == 0)
return_type = false;
The expression, in this case is: 0 isn't equal to 0 (0 != 0),
which obviously is false because 0 is equal to 0, so it will return false.
Now, if PREMIUM_TIMER_ENABLE = 1, the expression is 1 isn't equal to 0 (1 != 0).
This expression is true because 1 isn't equal to 0, and so it returns true.
So basically, whenever PREMIUM_TIMER_ENABLE is 0, it will return false.
Because 0 is equal to 0. With any other value, it will return true,
because 1, 2, 3, 4, 5, 6 etc. isn't equal to 0, which is what we asked for.