constrain
#define constrain(amt,low,high) ((amt)<(low)?(low):((amt)>(high)?(high):(amt)))
This macro constrains a number bewtween a min and max value. It returns the value if it is between low and high, high if value is greater, and low it it is lower.
Usage:
const int MAX = 20;
const int MIN = 12;
int a = 15;
int b = 5;
int c = 32;
int d = constrain(a, MIN, MAX); //d is a, because a was between the values
int e = constrain(b, MIN, MAX); //e is MIN, because b was less than MIN
int f = constrain(c, MIN, MAX); //f is MAX, becuase c was greater than MAX