X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitboard.cpp;h=ba00c78d876fb23fa0ebe3becf58185deb40429f;hp=04d12c5ebfe389d942a85236542a75b0cf095d90;hb=cad300cfab869a4e8dcc6b286f9b2e60d2827bed;hpb=6d24ef8585c2ed5618eb9b4ab1d8ee35a05ce2cd

diff --git a/src/bitboard.cpp b/src/bitboard.cpp
index 04d12c5e..ba00c78d 100644
--- a/src/bitboard.cpp
+++ b/src/bitboard.cpp
@@ -2,7 +2,7 @@
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
   Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2017 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2015-2018 Marco Costalba, Joona Kiiski, Gary Linscott, 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
@@ -54,7 +54,7 @@ namespace {
   Bitboard RookTable[0x19000];  // To store rook attacks
   Bitboard BishopTable[0x1480]; // To store bishop attacks
 
-  void init_magics(Bitboard table[], Magic magics[], Square deltas[]);
+  void init_magics(Bitboard table[], Magic magics[], Direction directions[]);
 
   // bsf_index() returns the index into BSFTable[] to look up the bitscan. Uses
   // Matt Taylor's folding for 32 bit case, extended to 64 bit by Kim Walisch.
@@ -188,7 +188,7 @@ void Bitboards::init() {
           for (Square s = SQ_A1; s <= SQ_H8; ++s)
               for (int i = 0; steps[pt][i]; ++i)
               {
-                  Square to = s + Square(c == WHITE ? steps[pt][i] : -steps[pt][i]);
+                  Square to = s + Direction(c == WHITE ? steps[pt][i] : -steps[pt][i]);
 
                   if (is_ok(to) && distance(s, to) < 3)
                   {
@@ -199,11 +199,11 @@ void Bitboards::init() {
                   }
               }
 
-  Square RookDeltas[] = { NORTH,  EAST,  SOUTH,  WEST };
-  Square BishopDeltas[] = { NORTH_EAST, SOUTH_EAST, SOUTH_WEST, NORTH_WEST };
+  Direction RookDirections[] = { NORTH,  EAST,  SOUTH,  WEST };
+  Direction BishopDirections[] = { NORTH_EAST, SOUTH_EAST, SOUTH_WEST, NORTH_WEST };
 
-  init_magics(RookTable, RookMagics, RookDeltas);
-  init_magics(BishopTable, BishopMagics, BishopDeltas);
+  init_magics(RookTable, RookMagics, RookDirections);
+  init_magics(BishopTable, BishopMagics, BishopDirections);
 
   for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1)
   {
@@ -225,14 +225,14 @@ void Bitboards::init() {
 
 namespace {
 
-  Bitboard sliding_attack(Square deltas[], Square sq, Bitboard occupied) {
+  Bitboard sliding_attack(Direction directions[], Square sq, Bitboard occupied) {
 
     Bitboard attack = 0;
 
     for (int i = 0; i < 4; ++i)
-        for (Square s = sq + deltas[i];
-             is_ok(s) && distance(s, s - deltas[i]) == 1;
-             s += deltas[i])
+        for (Square s = sq + directions[i];
+             is_ok(s) && distance(s, s - directions[i]) == 1;
+             s += directions[i])
         {
             attack |= s;
 
@@ -249,8 +249,9 @@ namespace {
   // chessprogramming.wikispaces.com/Magic+Bitboards. In particular, here we
   // use the so called "fancy" approach.
 
-  void init_magics(Bitboard table[], Magic magics[], Square deltas[]) {
+  void init_magics(Bitboard table[], Magic magics[], Direction directions[]) {
 
+    // Optimal PRNG seeds to pick the correct magics in the shortest time
     int seeds[][RANK_NB] = { { 8977, 44560, 54343, 38998,  5731, 95205, 104912, 17020 },
                              {  728, 10316, 55013, 32803, 12281, 15100,  16645,   255 } };
 
@@ -268,7 +269,7 @@ namespace {
         // the number of 1s of the mask. Hence we deduce the size of the shift to
         // apply to the 64 or 32 bits word to get the index.
         Magic& m = magics[s];
-        m.mask  = sliding_attack(deltas, s, 0) & ~edges;
+        m.mask  = sliding_attack(directions, s, 0) & ~edges;
         m.shift = (Is64Bit ? 64 : 32) - popcount(m.mask);
 
         // Set the offset for the attacks table of the square. We have individual
@@ -280,7 +281,7 @@ namespace {
         b = size = 0;
         do {
             occupancy[size] = b;
-            reference[size] = sliding_attack(deltas, s, b);
+            reference[size] = sliding_attack(directions, s, b);
 
             if (HasPext)
                 m.attacks[pext(b, m.mask)] = reference[size];