#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;
}
projects / hexagon / blobdiff