From 1c03f7b10ce8492b50630fce83dce6b62ba53734 Mon Sep 17 00:00:00 2001
From: Pavel <pavel-demin@outlook.com>
Date: Tue, 9 Nov 2021 10:05:06 +0100
Subject: [PATCH] fix heuristic in astar.cpp

---
 synchrod/astar.cpp | 29 +++++++++++++++++++----------
 1 file changed, 19 insertions(+), 10 deletions(-)

diff --git a/synchrod/astar.cpp b/synchrod/astar.cpp
index dfb8636..eccbf45 100644
--- a/synchrod/astar.cpp
+++ b/synchrod/astar.cpp
@@ -19,6 +19,12 @@ using namespace std;
 
 int deltas[4] = {-16, 16, -1, 1};
 
+union bytes
+{
+  int i;
+  char b[4];
+};
+
 struct result
 {
   double cost;
@@ -27,35 +33,38 @@ struct result
 
 struct result cost(const vector<double> &t, int players, int exits, int m, int l)
 {
-  int i, n, dn, p, e, mask;
+  int i, n, dn;
   double c, v;
+  union bytes p, e;
   struct result r;
-  p = players;
+  p.i = players;
+  e.i = exits;
   dn = deltas[m];
   c = 1;
   for(i = 0; i < 4; ++i)
   {
-    n = p >> i * 8 & 0xff;
-    e = exits >> i * 8 & 0xff;
-    if(n == e) continue;
+    n = p.b[i];
+    if(n == e.b[i]) continue;
     n += dn;
     v = t[n + i * l];
     if(v < 0) continue;
-    mask = 0xff << i * 8;
-    p = (p & ~mask) | (n << i * 8);
+    p.b[i] = n;
     c += v;
   }
   r.cost = c;
-  r.players = p;
+  r.players = p.i;
   return r;
 }
 
 double heuristic(int u, int d)
 {
-  int result, dx[4], i;
+  int dx[4], i;
+  union bytes a, b;
+  a.i = u;
+  b.i = d;
   for(i = 0; i < 4; ++i)
   {
-    dx[i] = abs(u >> i * 8 & 0xff) % 16 - abs(d >> i * 8 & 0xff) % 16 ;
+    dx[i] = abs(a.b[i] % 16 - b.b[i] % 16);
   }
   return MAX(dx[0], dx[2]) + MAX(dx[1], dx[3]);
 }