[Freeciv-Dev] (PR#11886) faster city_map_iterate

["Jason Short" <jdorje@xxxxxxxxxxxxxxxxxxxxx>]

<URL: http://bugs.freeciv.org/Ticket/Display.html?id=11886 >

This patch makes city_map_iterate much faster.  It is changed to be a 
wrapper for city_map_iterate_outwards.  This means that simple pointer 
lookups take the place of a function call and arithmetic in 
is_valid_city_coords.

This speeds up the CM run on Boston in the 10203 savegame from 2210 ms 
to 2100 ms.  Of course it should also have an affect anywhere else 
city_map_iterate is used (but generic_city_refresh is surely the biggest 
user).

The only tricky part is that city_map_iterate may no longer be used in 
generating the city map indices, for obvious reasons.  This means a 
small change to city.c with a comment about it.

-jason

? diff
? gmon.out
Index: common/city.c
===================================================================
RCS file: /home/freeciv/CVS/freeciv/common/city.c,v
retrieving revision 1.303
diff -u -r1.303 city.c
--- common/city.c       8 Jan 2005 09:44:39 -0000       1.303
+++ common/city.c       10 Jan 2005 19:41:45 -0000
@@ -172,10 +172,17 @@
   int i = 0, dx, dy;
   struct iter_index *array = city_map_iterate_outwards_indices;
 
+  /* We don't use city-map iterators in this function because they may
+   * rely on the indices that have not yet been generated. */
+
   city_tiles = 0;
-  city_map_iterate(city_x, city_y) {
-    city_tiles++;
-  } city_map_iterate_end;
+  for (dx = -CITY_MAP_RADIUS; dx <= CITY_MAP_RADIUS; dx++) {
+    for (dy = -CITY_MAP_RADIUS; dy <= CITY_MAP_RADIUS; dy++) {
+      if (is_valid_city_coords(dx + CITY_MAP_RADIUS, dy + CITY_MAP_RADIUS)) {
+       city_tiles++;
+      }
+    }
+  }
 
   /* Realloc is used because this function may be called multiple times. */
   array = fc_realloc(array, CITY_TILES * sizeof(*array));
Index: common/city.h
===================================================================
RCS file: /home/freeciv/CVS/freeciv/common/city.h,v
retrieving revision 1.193
diff -u -r1.193 city.h
--- common/city.h       8 Jan 2005 05:14:17 -0000       1.193
+++ common/city.h       10 Jan 2005 19:41:45 -0000
@@ -80,19 +80,8 @@
  * city map (i.e., positions that are workable by the city) in unspecified
  * order.
  */
-#define city_map_iterate(x, y)                                             \
-{                                                                          \
-  int _itr;                                                                \
-                                                                           \
-  for (_itr = 0; _itr < CITY_MAP_SIZE * CITY_MAP_SIZE; _itr++) {           \
-    const int x = _itr % CITY_MAP_SIZE, y = _itr / CITY_MAP_SIZE;          \
-                                                                           \
-    if (is_valid_city_coords(x, y)) {
-
-#define city_map_iterate_end                                               \
-    }                                                                      \
-  }                                                                        \
-}
+#define city_map_iterate(x, y) city_map_iterate_outwards(x, y)
+#define city_map_iterate_end city_map_iterate_outwards_end
 
 /* Cost in luxuries to make one citizen happier by one level. */
 #define HAPPY_COST 2