[Wesnoth-cvs-commits] wesnoth/src pathutils.cpp

[ott]

CVSROOT:        /cvsroot/wesnoth
Module name:    wesnoth
Branch:         
Changes by:     ott <address@hidden>    05/05/04 21:20:05

Modified files:
        src            : pathutils.cpp 

Log message:
        Small tweak to reduce code complexity, with also a 5-8% performance gain

CVSWeb URLs:
http://savannah.gnu.org/cgi-bin/viewcvs/wesnoth/wesnoth/src/pathutils.cpp.diff?tr1=1.4&tr2=1.5&r1=text&r2=text

Patches:
Index: wesnoth/src/pathutils.cpp
diff -u wesnoth/src/pathutils.cpp:1.4 wesnoth/src/pathutils.cpp:1.5
--- wesnoth/src/pathutils.cpp:1.4       Sat Feb 19 09:26:31 2005
+++ wesnoth/src/pathutils.cpp   Wed May  4 21:20:05 2005
@@ -7,12 +7,16 @@
 {
        const size_t hdistance = abs(a.x - b.x);
 
-       const size_t vpenalty = (is_even(a.x) && is_odd(b.x) && a.y < b.y ||
-                                is_even(b.x) && is_odd(a.x) && b.y < a.y) ? 
1:0;
-       const size_t vdistance = abs(a.y - b.y) + vpenalty;
-       const size_t vsavings = minimum<int>(vdistance,hdistance/2 + 
hdistance%2);
+       const size_t vpenalty = ( (is_even(a.x) && is_odd(b.x) && (a.y < b.y))
+               || (is_even(b.x) && is_odd(a.x) && (b.y < a.y)) ) ? 1 : 0;
 
-       return hdistance + vdistance - vsavings;
+       // for any non-negative integer i, i - i/2 - i%2 == i/2
+       // previously returned (hdistance + vdistance - vsavings)
+       // = hdistance + vdistance - minimum(vdistance,hdistance/2+hdistance%2)
+       // = maximum(hdistance, vdistance+hdistance-hdistance/2-hdistance%2)
+       // = maximum(hdistance,abs(a.y-b.y)+vpenalty+hdistance/2)
+
+       return maximum<int>(hdistance, abs(a.y - b.y) + vpenalty + hdistance/2);
 }
 
 void get_adjacent_tiles(const gamemap::location& a, gamemap::location* res)