[Freeciv-Dev] (PR#7251) new macros native_pos <-> index

["Jason Short" <jdorje@xxxxxxxxxxxxxxxxxxxxx>]

<URL: http://rt.freeciv.org/Ticket/Display.html?id=7251 >

The attached patch adds macros native_pos_to_index and index_to_native_pos.

These accomplish two things:

- They make the steps in the other macros more explicit.
- They will be of use in future functions that access values by native 
position.

Because of their extremely heavy use they obviously have to be macros 
(or inline functions).

jason

? diff
Index: common/map.h
===================================================================
RCS file: /home/freeciv/CVS/freeciv/common/map.h,v
retrieving revision 1.166
diff -u -r1.166 map.h
--- common/map.h        2004/01/13 03:20:17     1.166
+++ common/map.h        2004/01/16 05:00:20
@@ -209,6 +209,12 @@
 #define CHECK_INDEX(index) ((void)0)
 #endif
 
+#define native_pos_to_index(nat_x, nat_y)                                   \
+  ((nat_x) + (nat_y) * map.xsize)
+#define index_to_native_pos(pnat_x, pnat_y, index)                          \
+  (*(pnat_x) = (index) % map.xsize,                                         \
+   *(pnat_y) = (index) / map.xsize)
+
 /* Obscure math.  See explanation in doc/HACKING. */
 #define native_to_map_pos(pmap_x, pmap_y, nat_x, nat_y)                     \
   (topo_has_flag(TF_ISO)                                                    \
@@ -227,8 +233,7 @@
 /* index_to_map_pos(int *, int *, int) inverts map_pos_to_index */
 #define index_to_map_pos(pmap_x, pmap_y, index) \
   (CHECK_INDEX(index),                          \
-   *(pmap_x) = (index) % map.xsize,             \
-   *(pmap_y) = (index) / map.xsize,             \
+   index_to_native_pos(pmap_x, pmap_y, index),  \
    native_to_map_pos(pmap_x, pmap_y, *(pmap_x), *(pmap_y)))
 
 #define DIRSTEP(dest_x, dest_y, dir)   \
@@ -683,7 +688,7 @@
 
   CHECK_MAP_POS(map_x, map_y);
   map_to_native_pos(&nat_x, &nat_y, map_x, map_y);
-  return nat_x + nat_y * map.xsize;
+  return native_pos_to_index(nat_x, nat_y);
 }
 
 #endif  /* FC__MAP_H */