From 9ef3fe06a9e4dc439cb3be297d536a53aa87c254 Mon Sep 17 00:00:00 2001
From: ianfab <ianfab@users.noreply.github.com>
Date: Wed, 27 Jun 2018 22:37:20 +0200
Subject: [PATCH] Fix king of the hill and racing kings

Furthermore introduce some basic variant-specific bonuses.
---
 src/evaluate.cpp |   45 +++++++++++++++++++++++++++++++++++++++++++--
 src/position.h   |    5 +++++
 src/variant.cpp  |    4 ++--
 3 files changed, 50 insertions(+), 4 deletions(-)

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 7d1cd04..aaf3f89 100644
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -35,7 +35,7 @@ namespace Trace {
   enum Tracing { NO_TRACE, TRACE };
 
   enum Term { // The first 8 entries are reserved for PieceType
-    MATERIAL = 8, IMBALANCE, MOBILITY, THREAT, PASSED, SPACE, INITIATIVE, TOTAL, TERM_NB
+    MATERIAL = 8, IMBALANCE, MOBILITY, THREAT, PASSED, SPACE, INITIATIVE, VARIANT, TOTAL, TERM_NB
   };
 
   Score scores[TERM_NB][COLOR_NB];
@@ -201,6 +201,7 @@ namespace {
     template<Color Us> Score threats() const;
     template<Color Us> Score passed() const;
     template<Color Us> Score space() const;
+    template<Color Us> Score variant() const;
     ScaleFactor scale_factor(Value eg) const;
     Score initiative(Value eg) const;
 
@@ -758,6 +759,44 @@ namespace {
   }
 
 
+  // Evaluation::variant() computes variant-specific evaluation bonuses for a given side.
+
+  template<Tracing T> template<Color Us>
+  Score Evaluation<T>::variant() const {
+
+    constexpr Color Them = (Us == WHITE ? BLACK : WHITE);
+
+    Score score = SCORE_ZERO;
+
+    // Capture the flag
+    if (pos.capture_the_flag(Us))
+    {
+        Bitboard target_squares = pos.capture_the_flag(Us);
+        while (target_squares)
+        {
+            Square s = pop_lsb(&target_squares);
+            int dist =  distance(pos.square<KING>(Us), s)
+                      + popcount(pos.attackers_to(s) & pos.pieces(Them))
+                      + !!(pos.pieces(Us) & s);
+            score += make_score(3000, 3000) / (1 + dist * dist);
+        }
+    }
+
+    // nCheck
+    if (pos.max_check_count())
+    {
+        int remainingChecks = pos.max_check_count() - pos.checks_given(Us);
+        assert(remainingChecks > 0);
+        score += make_score(3000, 1000) / (remainingChecks * remainingChecks);
+    }
+
+    if (T)
+        Trace::add(VARIANT, Us, score);
+
+    return score;
+  }
+
+
   // Evaluation::initiative() computes the initiative correction value
   // for the position. It is a second order bonus/malus based on the
   // known attacking/defending status of the players.
@@ -870,7 +909,8 @@ namespace {
     score +=  king<   WHITE>() - king<   BLACK>()
             + threats<WHITE>() - threats<BLACK>()
             + passed< WHITE>() - passed< BLACK>()
-            + space<  WHITE>() - space<  BLACK>();
+            + space<  WHITE>() - space<  BLACK>()
+            + variant<WHITE>() - variant<BLACK>();
 
     score += initiative(eg_value(score));
 
@@ -938,6 +978,7 @@ std::string Eval::trace(const Position& pos) {
      << "     Threats | " << Term(THREAT)
      << "      Passed | " << Term(PASSED)
      << "       Space | " << Term(SPACE)
+     << "     Variant | " << Term(VARIANT)
      << " ------------+-------------+-------------+------------\n"
      << "       Total | " << Term(TOTAL);
 
diff --git a/src/position.h b/src/position.h
index 6fc2006..7e73ace 100644
--- a/src/position.h
+++ b/src/position.h
@@ -104,6 +104,7 @@ public:
   Bitboard capture_the_flag(Color c) const;
   bool flag_move() const;
   CheckCount max_check_count() const;
+  CheckCount checks_given(Color c) const;
   bool is_variant_end() const;
   bool is_variant_end(Value& result, int ply = 0) const;
 
@@ -328,6 +329,10 @@ inline CheckCount Position::max_check_count() const {
   return var->maxCheckCount;
 }
 
+inline CheckCount Position::checks_given(Color c) const {
+  return st->checksGiven[c];
+}
+
 inline bool Position::is_variant_end() const {
   Value result;
   return is_variant_end(result);
diff --git a/src/variant.cpp b/src/variant.cpp
index 75988fb..6fa79fc 100644
--- a/src/variant.cpp
+++ b/src/variant.cpp
@@ -116,7 +116,7 @@ void VariantMap::init() {
     const Variant* kingofthehill = [&]{
         Variant* v = new Variant();
         v->whiteFlag = make_bitboard(SQ_D4, SQ_E4, SQ_D5, SQ_E5);
-        v->whiteFlag = make_bitboard(SQ_D4, SQ_E4, SQ_D5, SQ_E5);
+        v->blackFlag = make_bitboard(SQ_D4, SQ_E4, SQ_D5, SQ_E5);
         v->flagMove = false;
         return v;
     } ();
@@ -124,7 +124,7 @@ void VariantMap::init() {
         Variant* v = new Variant();
         v->startFen = "8/8/8/8/8/8/krbnNBRK/qrbnNBRQ w - - 0 1";
         v->whiteFlag = Rank8BB;
-        v->whiteFlag = Rank8BB;
+        v->blackFlag = Rank8BB;
         v->flagMove = true;
         v->castling = false;
         v->checking = false;
-- 
1.7.0.4