map function high to low

[jbobrow]

Currently the map() function works with the following:
map(var, low_input, high_input, low_output, high_output)

i.e. lo,hi,lo,hi

I would like to have the function also work for the following:
lo,hi,hi,lo
hi,lo,hi,lo
hi,lo,lo,hi

Some common use case examples are mapping the remaining time from a timer which is going from high to low or wanting to dim brightness with the increase of a variable... All in all these are conveniences, but I have found that only working properly for the lo,hi,lo,hi makes it easy to make mistakes the the 3 other possible configurations. Working with words still makes sense, no need to account for negative numbers, I think that is a fine place to draw the line.

[bigjosh]

Of course it is easy to make a map() function that covers these additional cases, but these will expand the flash used by this already-too-big function by several times.

Maybe make a new expensive_map() function that does not require the arguments to be in min < max order and instead covers all the combinations?

Or maybe we could change the type of the inputs to be ints so that the function could use signed math rather than special casing out the combinations?

[jbobrow]

Using int makes a lot of sense, I’m trying to think of the main consequences of that change. Ints are twice the size, but I imagine the math is the expensive portion. This isn’t prohibitive for our launch games, but trying to make the platform friendlier for beginners.

[bigjosh]

Both int and word are 16 bits on this platform, only difference is that int uses one of those bits for sign so goes from -32768 to 32767 whereas word goes from 0-65535.