Question

If I wanted to find the absolute value of a 24-bit two’s complement integer, would it be best to mask the integer, and if needed negate the original number?

To better illustrate what I mean:

public static int bitwiseAbsoluteValue(int n) {
      if (n == 0x800000) {
           return 0x000000;
      } else {
           if ((n & 0x800000) == 0x800000) {
                 return (~n + 1) & 0x7FFFFF;
           } else {
                 return n;
           }
      }
}

Would this work?

Answer 1

You’d also need to mask the first return value:

return (~num + 1) & 0x7FFFFF;

And you’d need to work out what you want to do if the the value passed in is 0x800000. The current function would return 0, which is obviously not correct.