t_process *engine_process_get(t_engine *engine,char *name)
{
void *ptr;
ptr=lst_get(engine->processes,name);
if(ptr)
{
return (t_process *)ptr;
}
else
{
return NULL;
}
}
/** Build the maze by removing walls according to Prim's algorithm.
*
* @param maze a maze with all walls present.
*/
static void build_prim(maze_t* maze) {
// MST edges and cells. If (a, b) in mst_edges, then (b, a) not in
// mst_edges. (a, b) in mst_edges iff a, b both in mst_cells.
list356_t* mst_edges = make_list() ;
list356_t* mst_cells = make_list() ;
// The frontier. This is the collection of edges between cells in the MST
// and cells not in the MST. If (a, b) in frontier, then a in mst_cells
// and b not in mst_cells.
list356_t* frontier = make_list() ;
// Choose two adjacent cells at random to put into the MST, then
// populate the frontier accordinately. For simplicitly, choose a
// cell in the interior of the maze, then randomly choose a direction
// for the other cell.
cell_t* start =
get_cell(maze, random_limit(1, maze->nrows-1),
random_limit(1, maze->ncols-1));
unsigned char direction = 1 << random_limit(0, 4) ;
cell_t* next = get_neighbor(maze, start, direction) ;
/*
debug("Removing (%d, %d) - (%d, %d).\n",
start->r, start->c, next->r, next->c) ;
*/
remove_wall(maze, start, direction) ;
edge_t init_edge = (edge_t){start, next} ;
lst_add(mst_edges, &init_edge) ;
lst_add(mst_cells, start) ;
lst_add(mst_cells, next) ;
for (int d=0; d<4; ++d) {
if (directions[d] != direction && is_cell(maze, start, directions[d])) {
cell_t* c = get_neighbor(maze, start, directions[d]) ;
edge_t* e = malloc(sizeof(edge_t)) ;
e->a = start ; e->b = c ;
lst_add(frontier, e) ;
}
}
for (int d=0; d<4; ++d) {
if (directions[d] != opposite(direction)
&& is_cell(maze, next, directions[d])) {
cell_t* c = get_neighbor(maze, next, directions[d]) ;
edge_t* e = malloc(sizeof(edge_t)) ;
e->a = next ; e->b = c ;
lst_add(frontier, e) ;
}
}
// As long as we don't have all the cells in the MST, choose an
// edge in the frontier at random. Put the edge in the MST
// and compute the new edges to add to the frontier.
while (lst_size(mst_cells) < (maze->nrows)*(maze->ncols)) {
int p = random_limit(0, lst_size(frontier)) ;
edge_t* edge = lst_get(frontier, p) ;
cell_t* old_cell = edge->a ;
cell_t* new_cell = edge->b ;
/*
debug("Removing (%d, %d) - (%d, %d).\n",
old_cell->r, old_cell->c, new_cell->r, new_cell->c) ;
*/
remove_wall(maze, old_cell, get_direction(old_cell, new_cell)) ;
lst_add(mst_edges, edge) ;
lst_add(mst_cells, new_cell) ;
for (int d=0; d<4; ++d) {
unsigned char dir = directions[d] ;
if (is_cell(maze, new_cell, dir)) {
cell_t* adj_cell = get_neighbor(maze, new_cell, dir) ;
edge_t* edge2 = malloc(sizeof(edge_t)) ;
edge2->a = new_cell ; edge2->b = adj_cell ;
if (lst_contains(mst_cells, adj_cell, cell_cmp)) {
lst_remove(frontier, edge2, edge_cmp) ;
if (adj_cell != old_cell) free(edge2) ;
}
else {
lst_add(frontier, edge2) ;
}
}
}
}
}
