X-Git-Url: https://pd.if.org/git/?p=hexagon;a=blobdiff_plain;f=astar.c;h=cabe5d08c4c36dec8d0bf86490fe5e2424e4a2a2;hp=37bc404ac39a2486496df0ac1ad7d91b03390d23;hb=5c48a06bc8649958e69013c53e925b83398ebc74;hpb=67fdcec57ab31e7a972ed624ab5f6df866313206

diff --git a/astar.c b/astar.c
index 37bc404..cabe5d0 100644
--- a/astar.c
+++ b/astar.c
@@ -4,158 +4,292 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <limits.h>
+#include <errno.h>
 
-struct astar_hex {
-	int hex;
-	int f, g, h;
-	int parent;
-};
-
-struct astar {
-	int open, closed; /* how many in open or closed */
-	int closedroom, openroom; /* how much is malloced */
-	struct astar_hex *openlist;
-	struct astar_hex *closedlist;
-	int known, index;
-	int error;
-};
-
-static void astar_init(struct astar *state) {
+/*
+ * TODO use binary heap for the openlist and closed list.
+ * open list should be a min-heap on the f value
+ * closed list is just tested for existence, so a sort on
+ * the hex id is fine
+ */
+
+#if 0
+#define DEBUG_ASTAR 1 
+#endif
+
+static double default_metric(int a, int b) {
+	return 1.0;
+}
+
+static double default_heuristic(int a, int b) {
+	return (double)HL_distance(a, b);
+}
+
+struct HL_astar *HL_astar_init(struct HL_astar *state) {
+	if (!state) {
+		state = malloc(sizeof *state);
+		if (!state) return NULL;
+		state->malloced = 1;
+	}
+	state->sets = 0;
 	state->open = 0;
 	state->closed = 0;
-	state->closedroom = 0;
-	state->openroom = 0;
-	state->openlist = 0;
-	state->closedlist = 0;
+	state->nodes = 0;
+	state->allocated = 0;
 	state->error = 0;
 	state->known = 0;
 	state->index = 0;
+	state->pathlen = 0;
+
+	state->metric = default_metric;
+	state->heuristic = default_heuristic;
+	state->neighbor = HL_adjacent_hex;
 
-	return;
+	return state;
 }
 
-static void removeopen(struct astar *s, int hex) {
-	int index;
+/*
+ * Reset a state to enpty.  Doesn't free memory, so it
+ * can be reused.
+ */
+struct HL_astar *HL_astar_clear(struct HL_astar *s) {
+	if (!s) return NULL;
 
-	if (s->error) return;
-	if (s->open == 0) return;
+	s->open = 0;
+	s->closed = 0;
+	s->nodes = 0;
+	s->pathlen = 0;
 
-	if (s->known != hex) {
-		for (index = 0; index < s->open; index++) {
-			if (s->openlist[index].hex == hex) break;
-		}
-	} else {
-		index = s->index;
-		s->known = 0; s->index = 0;
+	return s;
+}
+
+void HL_astar_free(struct HL_astar *s) {
+	free(s->sets);
+	if (s->malloced) {
+		free(s);
 	}
-	s->openlist[index] = s->openlist[open];
-	s->open--;
 }
 
-static void addopen(struct astar *s, int hex) {
-	struct astar_hex *mem;
-	if (s->error) return;
+static struct HL_astar_hex *add_open(struct HL_astar *s, int hex) {
+	struct HL_astar_hex *node;
+
+	if (!s || s->error) return NULL;
+
+	/* TODO check in open or closed */
 
-	if (s->open + 1 > s->openroom) {
-		mem = realloc(s->openlist, s->openroom * 2 * sizeof *mem);
-		if (mem == NULL) {
-			s->error = errno;
-			return;
+	if (s->nodes == s->allocated) {
+		int newalloc;
+		struct HL_astar_hex *alloc;
+		if (s->allocated) {
+			newalloc = s->allocated * 2;
+		} else {
+			newalloc = 16;
 		}
-		state->openlist = mem;
-		s->openroom = s->openroom * 2;
+		alloc = realloc(s->sets, newalloc * sizeof *node);
+		if (!alloc) {
+			s->error = 1;
+			return NULL;
+		}
+		s->sets = alloc;
+		s->allocated = newalloc;
 	}
 
-	s->openlist[s->open].hex = hex;
-	s->openlist[s->open].f = 0;
-	s->openlist[s->open].g = 0;
-	s->openlist[s->open].h = 0;
-	s->known = hex;
-	s->index = s->open;
-	s->open = s->open + 1;
+	node = &s->sets[s->nodes++];
+
+	node->hex = hex;
+	node->g = 0.0;
+	node->f = 0.0;
+	node->h = 0.0;
+	node->open = 1;
+	node->parent = 0;
+	if (s->open) s->open->prev = node;
+	node->next = s->open;
+	node->prev = NULL;
+	s->open = node;
+
+	return node;
 }
 
-int lowrank(struct astar *s) {
-	int f;
-	int hex;
-	int i;
+static struct HL_astar_hex *closehex(struct HL_astar *s, struct HL_astar_hex *h) {
+	if (!s || s->error) return NULL;
+	if (!h) {
+		s->error = 1;
+		return NULL;
+	}
 
-	if (!s || s->open = 0) return 0;
+#ifdef DEBUG_ASTAR
+	fprintf(stderr, "Closing hex: (%d,%d)\n",  HL_cantor_x(h->hex), HL_cantor_y(h->hex));
+#endif
+	h->open = 0;
+	if (h->prev) h->prev->next = h->next;
+	if (h->next) h->next->prev = h->prev;
+	if (s->closed) s->closed->prev = h;
+	if (s->open == h) s->open = h->next;
+	h->next = s->closed;
+	s->closed = h;
+	h->prev = NULL;
 
-	hex = s->openlist[0].hex;
-	f = s->openlist[0].f;
+	return h;
+}
 
-	for(i=1; i < s->open; i++) {
-		if (s->openlist[i].f < f) {
-			hex = s->openlist[i].hex;
-			f = s->openlist[i].f;
-		}
-		/* TODO check s->openlist[i].tiebreak */
+struct HL_astar_hex *in_closed(struct HL_astar *s, int hex) {
+	struct HL_astar_hex *h;
+	if (!s) return 0;
+
+	for(h = s->closed; h; h = h->next) {
+		if (h->hex == hex) return h;
 	}
+	return NULL;
+}
+
+struct HL_astar_hex *in_open(struct HL_astar *s, int hex) {
+	struct HL_astar_hex *h;
+	if (!s) return 0;
 
-	return hex;
+	for(h = s->open; h; h = h->next) {
+		if (h->hex == hex) return h;
+	}
+	return NULL;
 }
 
-static int default_metric(int a, int b) {
-	return 1;
+static struct HL_astar_hex *lowrank(struct HL_astar *s) {
+	struct HL_astar_hex *n, *r;
+
+	if (!s || s->open == 0) return 0;
+
+	r = s->open;
+	for(n = r; n; n = n->next) {
+		if (n->f < r->f) {
+			r = n;
+		}
+	}
+
+	return r;
 }
 
 /*
  * find a path from start to end.  we use A*
  */
-int HL_findpath(int start, int end, int psize, int *path,
-		double (*metric)(int,int)) {
-	int neighbors[6];
-	int count;
-	int cur = 0;
-	struct astar state;
-	int neighbor;
-
-	if (start == end) return 0;
-	if (!metric) metric = default_metric;
-
-	astar_init(&state);
-	addopen(&state, start);
-
-	while (1) {
-		cur = lowrank(&state);
-		if (cur == end) {
+int HL_findpath(struct HL_astar *s, int loops) {
+	int dir, y;
+	struct HL_astar_hex *node, *x, *yopen;
+	int tent_better;
+	double cost;
+
+	s->error = 0;
+
+	if (s->start == s->goal) return 0;
+
+	node = add_open(s, s->start);
+	node->g = 0.0;
+	node->h = s->heuristic(s->start, s->goal);
+	node->f = node->h;
+
+#ifdef DEBUG_ASTAR
+	fprintf(stderr, "A* findpath: ");
+	fprintf(stderr, "(%d,%d)",  HL_cantor_x(s->start), HL_cantor_y(s->start));
+	fprintf(stderr, " -> ");
+	fprintf(stderr, "(%d,%d)",  HL_cantor_x(s->goal), HL_cantor_y(s->goal));
+	fprintf(stderr, "\n");
+#endif
+
+	while (s->open) {
+
+#ifdef DEBUG_ASTAR
+	fprintf(stderr, "open list: ");
+	for(x = s->open; x; x = x->next) {
+		fprintf(stderr, "(%d,%d)",  HL_cantor_x(x->hex), HL_cantor_y(x->hex));
+	}
+	fprintf(stderr, "\n");
+	fprintf(stderr, "closed list: ");
+	for(x = s->closed; x; x = x->next) {
+		fprintf(stderr, "(%d,%d)",  HL_cantor_x(x->hex), HL_cantor_y(x->hex));
+	}
+	fprintf(stderr, "\n");
+#endif
+
+		x = lowrank(s);
+#ifdef DEBUG_ASTAR
+		fprintf(stderr, "checking lowest f hex = (%d,%d) f = %f, g = %f, h = %f\n",
+			HL_cantor_x(x->hex), HL_cantor_y(x->hex),
+				x->f, x->g, x->h
+				);
+#endif
+		if (x->hex == s->goal) {
 			break;
 		}
-		addclosed(&state, cur);
-		count = HL_hexes_at_range(cur->hex, 1, neighbors, 6);
-		for (i=0;i<count;i++) {
-			neighbor = neighbors[i];
-			cost = g(&state, current) + metric(current, neighbor);
-			if (inopen(&state, neighbor) && cost < g(&state, neighbor)) {
-				removeopen(&state, neighbor);
-			} else
-			if (inclosed(&state, neighbor) && cost < g(&state, neighbor)) {
-				/* should never happen with
-				 * admissible heuristic
-				 */
-				removeclosed(&state, neighbor);
-			} else
-			if (!inopen(&state, neighbor) && !inclosed(&state, neighbor)) {
-				addopen(&state, neighbor);
-				setg(&state, neighbor, cost);
-				setrank(&state, neighbor, cost + h(neighbor,end));
-				setparent(&state, neighbor, current);
+		closehex(s, x);
+		for (dir = 0; y = s->neighbor(x->hex, dir); dir++) {
+			if (in_closed(s, y)) {
+				continue;
+			}
+
+			cost = x->g + s->metric(x->hex, y);
+
+			yopen = in_open(s, y);
+			if (! yopen) {
+				yopen = add_open(s, y);
+
+				tent_better = 1;
+			} else if (cost < yopen->g) {
+				tent_better = 1;
 			} else {
-				abort();
+				tent_better = 0;
+			}
+
+			if (tent_better) {
+				if (yopen->parent) {
+					if (x->f < yopen->parent->f) {
+						yopen->parent = x;
+					}
+				} else {
+					yopen->parent = x;
+				}
+				yopen->g = cost;
+				yopen->h = s->heuristic(y, s->goal);
+				yopen->f = yopen->g + yopen->h;
+#ifdef DEBUG_ASTAR
+		fprintf(stderr, "maybe better hex = (%d,%d) f = %f, g = %f, h = %f\n",
+			HL_cantor_x(yopen->hex), HL_cantor_y(yopen->hex),
+				yopen->f, yopen->g, yopen->h
+				);
+#endif
 			}
 		}
 	}
 
-	count = 0;
-	while (parent(&state, cur) != start) {
-		count++;
-		cur = parent(&state, cur);
-	}
-	cur = end;
-	while (parent(&state, cur) != start) {
-		path[count--] = cur;
-		cur = parent(&state, cur);
+	/* error no path ? */
+	if (x->hex != s->goal) {
+		s->error = 1;
+		return 0;
 	}
 
+#ifdef DEBUG_ASTAR
+	fprintf(stderr, "found path: ");
+#endif
+
+	/* reconstruct path */
+	s->to = x;
+	x->next = 0;
+	for (s->pathlen = 0, yopen = x; yopen; yopen = yopen->parent) {
+		if (yopen->parent) {
+			yopen->parent->next = yopen;
+		}
+		if (yopen->hex == s->start) s->from = yopen;
+#ifdef DEBUG_ASTAR
+		fprintf(stderr, "(%p %d %d,%d)",
+				yopen, yopen->hex,
+				HL_cantor_x(yopen->hex),
+				HL_cantor_y(yopen->hex)
+				);
+#endif
+		s->pathlen++;
+	};
+	s->pathlen--;
+
+#ifdef DEBUG_ASTAR
+	fprintf(stderr, "\n");
+#endif
+
+	return s->pathlen;
 }