[Freeciv-Dev] PATCH: is_border_pos macro (PR#1006)

[jdorje@xxxxxxxxxxxxxxxxxxxxx]

This teeny-tiny patch introduces the desired topology expression
IS_BORDER_POS(x, y).  This macro returns TRUE iff (x, y) is on the
"border" of the map; that is, if any of its 8 neighbors are not normal
(proper).  It is not truly needed for any operations (yet), but is of
use in optimizing adjcancy iterators.

To preserve locality, I stuck the macro definition right in the middle
of the other is_*** topological functions.  It can be moved up above or
below them as desired.

jason

Index: common/map.h
===================================================================
RCS file: /home/freeciv/CVS/freeciv/common/map.h,v
retrieving revision 1.96
diff -u -r1.96 map.h
--- common/map.h        2001/10/09 16:26:46     1.96
+++ common/map.h        2001/10/12 13:03:19
@@ -232,6 +232,11 @@
 int check_coords(int *x, int *y);
 int is_real_tile(int x, int y);
 int is_normal_map_pos(int x, int y);
+/* A "border position" is any one that has adjacent positions
+   that are not normal/proper. */
+#define IS_BORDER_POS(x, y)                  \
+  ((y) == 0 || (x) == 0 ||                   \
+   (y) == map.ysize-1 || (x) == map.xsize-1)
 int normalize_map_pos(int *x, int *y);
 void nearest_real_pos(int *x, int *y);
 
@@ -404,10 +409,7 @@
   int MACRO_center_y = (center_y);                                            \
   assert(0 <= MACRO_center_y && MACRO_center_y < map.ysize                    \
          && 0 <= MACRO_center_x && MACRO_center_x < map.xsize);               \
-  MACRO_border = (MACRO_center_y == 0                                         \
-                  || MACRO_center_x == 0                                      \
-                  || MACRO_center_y == map.ysize-1                            \
-                  || MACRO_center_x == map.xsize-1);                          \
+  MACRO_border = IS_BORDER_POS(MACRO_center_x, MACRO_center_y);               \
   for (dir_itr = 0; dir_itr < 8; dir_itr++) {                                 \
     DIRSTEP(x_itr, y_itr, dir_itr);                                           \
     x_itr += MACRO_center_x;                                                  \