/* cache DoGetDirection().
* To avoid excessive use of direction calculation, cache the values for
* [-5..5] for both x/y. Anything outside of that is calcualted on the fly.
*
* @return A bitmask for N, NE, S, SE, etc. indicating the directions for
* this movement.
*/
static int
GetDirection(int dx, int dy){
static int cache[DIRECTION_CACHE_SIZE][DIRECTION_CACHE_SIZE];
int dir;
if (abs(dx) <= DIRECTION_CACHE_RANGE && abs(dy) <= DIRECTION_CACHE_RANGE) {
/* cacheable */
dir = cache[DIRECTION_CACHE_RANGE+dx][DIRECTION_CACHE_RANGE+dy];
if(dir == 0) {
dir = DoGetDirection(dx, dy);
cache[DIRECTION_CACHE_RANGE+dx][DIRECTION_CACHE_RANGE+dy] = dir;
}
}else{
/* non-cacheable */
dir = DoGetDirection(dx, dy);
}
return dir;
}
/* cache DoGetDirection(). */
static int
GetDirection(int dx, int dy){
static int cache[DIRECTION_CACHE_SIZE][DIRECTION_CACHE_SIZE];
int i;
if (abs(dx) <= DIRECTION_CACHE_RANGE &&
abs(dy) <= DIRECTION_CACHE_RANGE) {
/* cacheable */
i = cache[DIRECTION_CACHE_RANGE+dx][DIRECTION_CACHE_RANGE+dy];
if(i != 0){
return i;
}else{
i = DoGetDirection(dx, dy);
cache[DIRECTION_CACHE_RANGE+dx][DIRECTION_CACHE_RANGE+dy] = i;
return i;
}
}else{
/* non-cacheable */
return DoGetDirection(dx, dy);
}
}
