for short lighthouse ranges, don't use lists.

src/reports.c

@@ -1112,30 +1112,43 @@ void reports_done(void) {
     }
 }
 
-static int get_regions_distance_arr(region *r, int radius,
+int get_regions_distance_arr(region *rc, int radius, region *result[], int size)
-                                    region *result[], int size)
 {
     int n = 0, i;
     
     if (size>n) {
-        result[n++] = r;
+        result[n++] = rc;
     }
     for (i = 0; i != n; ++i) {
+        region *r;
+        int dist;
+
+        r = result[i];
+        dist = distance(rc, r);
+        if (dist<radius) {
             region *adj[MAXDIRECTIONS];
             int d;
 
-        r = result[i];
             get_neighbours(r, adj);
             for (d = 0; d != MAXDIRECTIONS; ++d) {
                 r = adj[d];
+                if (r) {
                     if (size > n) {
+                        if (dist < distance(rc, r)) {
                             result[n++] = r;
                         }
                     }
+                    else {
+                        return -1;
                     }
                 }
+            }
+        }
+    }
+    return n;
+}
 
-static quicklist *get_regions_distance(region * root, int radius)
+quicklist *get_regions_distance(region * root, int radius)
 {
     quicklist *ql, *rlist = NULL;
     int qi = 0;
@@ -1193,11 +1206,8 @@ static void add_seen_nb(faction *f, region *r, seen_mode mode) {
 
 /** mark all regions seen by the lighthouse.
  */
-static void prepare_lighthouse(building * b, report_context *ctx)
+static void prepare_lighthouse_ql(faction *f, quicklist *rlist) {
-{
+    quicklist *ql;
-    faction *f = ctx->f;
-    int range = lighthouse_range(b, f);
-    quicklist *ql, *rlist = get_regions_distance(b->region, range);
     int qi;
 
     for (ql = rlist, qi = 0; ql; ql_advance(&ql, &qi, 1)) {
@@ -1209,6 +1219,29 @@ static void prepare_lighthouse(building * b, report_context *ctx)
     ql_free(rlist);
 }
 
+static void prepare_lighthouse(building * b, report_context *ctx)
+{
+    faction *f = ctx->f;
+    int range = lighthouse_range(b, f);
+
+    if (range > 2) {
+        prepare_lighthouse_ql(f, get_regions_distance(b->region, range));
+    }
+    else {
+        region *result[64];
+        int n, i;
+
+        n = get_regions_distance_arr(b->region, range, result, 64);
+        assert(n > 0 && n <= 64);
+        for (i = 0; i != n; ++i) {
+            region *rl = result[i];
+            if (!fval(rl->terrain, FORBIDDEN_REGION)) {
+                add_seen_nb(f, rl, seen_lighthouse);
+            }
+        }
+    }
+}
+
 void reorder_units(region * r)
 {
     unit **unext = &r->units;

src/reports.h

@@ -49,7 +49,8 @@ extern "C" {
     struct unit *can_find(struct faction *, struct faction *);
 
     bool omniscient(const struct faction *f);
-
+    struct quicklist *get_regions_distance(struct region * root, int radius);
+    int get_regions_distance_arr(struct region *r, int radius, struct region *result[], int size);
     /* funktionen zum schreiben eines reports */
     void sparagraph(struct strlist **SP, const char *s, unsigned int indent, char mark);
     void lparagraph(struct strlist **SP, char *s, unsigned int indent, char mark);

src/reports.test.c

@@ -425,9 +425,47 @@ static void test_seen_travelthru(CuTest *tc) {
     test_cleanup();
 }
 
+static void test_region_distance(CuTest *tc) {
+    region *r;
+    region *result[8];
+    test_setup();
+    r = test_create_region(0, 0, 0);
+    CuAssertIntEquals(tc, 1, get_regions_distance_arr(r, 0, result, 8));
+    CuAssertPtrEquals(tc, r, result[0]);
+    CuAssertIntEquals(tc, 1, get_regions_distance_arr(r, 1, result, 8));
+    test_create_region(1, 0, 0);
+    test_create_region(0, 1, 0);
+    CuAssertIntEquals(tc, 1, get_regions_distance_arr(r, 0, result, 8));
+    CuAssertIntEquals(tc, 3, get_regions_distance_arr(r, 1, result, 8));
+    CuAssertIntEquals(tc, 3, get_regions_distance_arr(r, 2, result, 8));
+    test_cleanup();
+}
+
+static void test_region_distance_ql(CuTest *tc) {
+    region *r;
+    quicklist *ql;
+    test_setup();
+    r = test_create_region(0, 0, 0);
+    ql = get_regions_distance(r, 0);
+    CuAssertIntEquals(tc, 1, ql_length(ql));
+    CuAssertPtrEquals(tc, r, ql_get(ql, 0));
+    ql_free(ql);
+    test_create_region(1, 0, 0);
+    test_create_region(0, 1, 0);
+    ql = get_regions_distance(r, 1);
+    CuAssertIntEquals(tc, 3, ql_length(ql));
+    ql_free(ql);
+    ql = get_regions_distance(r, 2);
+    CuAssertIntEquals(tc, 3, ql_length(ql));
+    ql_free(ql);
+    test_cleanup();
+}
+
 CuSuite *get_reports_suite(void)
 {
     CuSuite *suite = CuSuiteNew();
+    SUITE_ADD_TEST(suite, test_region_distance);
+    SUITE_ADD_TEST(suite, test_region_distance_ql);
     SUITE_ADD_TEST(suite, test_prepare_report);
     SUITE_ADD_TEST(suite, test_seen_neighbours);
     SUITE_ADD_TEST(suite, test_seen_travelthru);