How to make artificial underflow/ overflow?

February 3, 2022

I’d like to clamp calculations in the range of 0-360 in my program. I know if you have an 8-bit integer adding 255 + 1 will overflow to 0 and likewise, 0 – 1 will underflow to 255.
I wrote this function as a test:

//only for negative numbers
function clampTo360 (a) {
  if (a < 0) {
    var b = 361 + a;
    if (b > 0) {
      return b;
    } else {
      clampTo360(b);
    }
  }
}

Is there a better way to code a function so the calculation 0 – 1 will return 360?

>Solution :

You can make use of the modulo operator here. However, underflowing inputs will result in negative values.

To avoid that you can add 360 to get a number in the interval [0; 720), and apply the modulo operator again to get a result between 0 and 360:

function clampTo360(g) {
    return (g % 360 + 360) % 360
}
console.log(clampTo360(720))
console.log(clampTo360(360))
console.log(clampTo360(-360))
console.log(clampTo360(-720))