X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fdirection.cpp;h=ebff65b16b9b781f307810524a005f2f32cab3cc;hp=abbd0aca00bf8ebaa1eb32c25854da47cdfee217;hb=cb7f20913e04b051fea6ac9a4055a4e86be452d1;hpb=c97104e8540b72ee2c6c9c13d3773d2c0f9ec32f

diff --git a/src/direction.cpp b/src/direction.cpp
index abbd0aca..ebff65b1 100644
--- a/src/direction.cpp
+++ b/src/direction.cpp
@@ -1,7 +1,7 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
-  Copyright (C) 2008 Marco Costalba
+  Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -22,42 +22,39 @@
 //// Includes
 ////
 
-#include "direction.h"
 #include "square.h"
 
+int8_t DirectionTable[64][64];
 
-////
-//// Variables
-////
 
-uint8_t DirectionTable[64][64];
-uint8_t SignedDirectionTable[64][64];
+static SquareDelta direction(Square orig, Square dest) {
 
+  const SquareDelta directions[] = {
+      DELTA_E, DELTA_N, DELTA_NE, DELTA_NW, DELTA_W, DELTA_S, DELTA_SW, DELTA_SE
+  };
 
-////
-//// Functions
-////
+  Square from, to;
 
-void init_direction_table() {
-  SquareDelta deltas[8] = {
-    DELTA_E, DELTA_W, DELTA_N, DELTA_S, DELTA_NE, DELTA_SW, DELTA_NW, DELTA_SE
-  };
-  for(Square s1 = SQ_A1; s1 <= SQ_H8; s1++)
-    for(Square s2 = SQ_A1; s2 <= SQ_H8; s2++) {
-      DirectionTable[s1][s2] = uint8_t(DIR_NONE);
-      SignedDirectionTable[s1][s2] = uint8_t(SIGNED_DIR_NONE);
-      if(s1 == s2) continue;
-      for(SignedDirection d = SIGNED_DIR_E; d <= SIGNED_DIR_SE; d++) {
-        SquareDelta delta = deltas[d];
-        Square s3, s4;
-        for(s4 = s1 + delta, s3 = s1;
-            square_distance(s4, s3) == 1 && s4 != s2 && square_is_ok(s4);
-            s3 = s4, s4 += delta);
-        if(s4 == s2 && square_distance(s4, s3) == 1) {
-          SignedDirectionTable[s1][s2] = uint8_t(d);
-          DirectionTable[s1][s2] = uint8_t(d/2);
-          break;
-        }
+  for (int idx = 0; idx < 8; idx++)
+  {
+      from = orig;
+      to = from + directions[idx];
+
+      while (to != dest && square_distance(to, from) == 1 && square_is_ok(to))
+      {
+          from = to;
+          to += directions[idx];
       }
-    }
+
+      if (to == dest && square_distance(from, to) == 1)
+          return directions[idx];
+  }
+  return DELTA_NONE;
+}
+
+void init_direction_table() {
+
+  for (Square s1 = SQ_A1; s1 <= SQ_H8; s1++)
+      for (Square s2 = SQ_A1; s2 <= SQ_H8; s2++)
+          DirectionTable[s1][s2] = uint8_t(direction(s1, s2));
 }