2016-07-08: Week 2: Day 8

Agenda

1. Weekly goal: by end of today, each group should demonstrate a fully functioning game simulation which extends PinballLogic example.

Integer Functions

Mappings from integers to integers can be implemented many, many ways. Here are just a few simple examples. First, pure program logic:

int func(int score)
{
   switch(score) {
      case 0:
         return 0;
      case 1:
         return 1;

      // what happens for other values?
      default:
         return -1;
   }
 }

Following is a table-driven example. Note that use of const to hint that the table itself won't be changed. (Aside: to really save memory space, see the use of PROGMEM with access functions to place tables in physical read-only memory.)

const int table[2] = {0, 1};

int func(int score)
{
   if (score >= 0 && score < 2) {
      return table[score];
   } else {
      return -1;
   }
}

Of if the mapping can be written as a closed-form expression, then plain arithmetic can often be the most compact code:

int func(int score)
{
   if (score >= 0 && score < 2) {
      return (score & 1);  // bitwise-and operation
   } else {
      return -1;
   }
}