Support XBoard/CECP protocol

src/Makefile

@@ -38,7 +38,7 @@ PGOBENCH = ./$(EXE) bench
 ### Object files
 OBJS = benchmark.o bitbase.o bitboard.o endgame.o evaluate.o main.o \
 	material.o misc.o movegen.o movepick.o pawns.o position.o psqt.o \
-	search.o thread.o timeman.o tt.o uci.o ucioption.o syzygy/tbprobe.o
+	search.o thread.o timeman.o tt.o uci.o ucioption.o xboard.o syzygy/tbprobe.o
 
 ### Establish the operating system name
 KERNEL = $(shell uname -s)

src/position.cpp

@@ -259,26 +259,61 @@ Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Th
 
   ss >> std::noskipws;
 
+  // Detect FEN format
+  bool xboard = ss.str().find('*') != std::string::npos;
+
   // 1. Piece placement
-  while ((ss >> token) && !isspace(token))
+  // Black gating pieces in XBoard format
+  if (xboard)
+  {
+      for (Square s = SQ_A8; (ss >> token) && token != '/' && s <= SQ_H8; s++)
+      {
+          if ((idx = PieceToChar.find(token)) != string::npos)
+          {
+              set_gating_type(type_of(Piece(idx)));
+              put_gating_piece(BLACK, s);
+          }
+      }
+  }
+
+  while ((ss >> token) && !isspace(token) && token != '[')
   {
       if (isdigit(token))
           sq += (token - '0') * EAST; // Advance the given number of files
 
       else if (token == '/')
+      {
           sq += 2 * SOUTH;
+          if (sq < SQ_A1)
+              break;
+      }
 
       else if ((idx = PieceToChar.find(token)) != string::npos)
       {
           put_piece(Piece(idx), sq);
           ++sq;
       }
+  }
 
-      else if (token == '[')
-          break; // Stop before gating pieces
+  // White gating pieces in XBoard format
+  if (xboard)
+  {
+      Square s1 = SQ_A1, s2 = SQ_A1;
+      for (Square s = SQ_A1; (ss >> token) && !isspace(token) && s <= SQ_H1; s++)
+      {
+          if ((idx = PieceToChar.find(token)) != string::npos)
+          {
+              if (type_of(Piece(idx)) == gating_piece(GATE_1))
+                  s1 = s;
+              else
+                  s2 = s;
+          }
+      }
+      put_gating_piece(WHITE, s1);
+      put_gating_piece(WHITE, s2);
   }
   // Gating pieces
-  if (!isspace(token))
+  else if (token == '[')
       while ((ss >> token) && !isspace(token))
       {
           // Allow various formats here. Rank and slash are optional.
@@ -331,7 +366,7 @@ Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Th
       else if (token == 'Q')
           for (rsq = relative_square(c, SQ_A1); piece_on(rsq) != rook; ++rsq) {}
 
-      else if (token >= 'A' && token <= 'H')
+      else if (isChess960 && token >= 'A' && token <= 'H')
           rsq = make_square(File(token - 'A'), relative_rank(c, RANK_1));
 
       else

src/search.cpp

@@ -134,7 +134,7 @@ namespace {
             pos.undo_move(m);
         }
         if (Root)
-            sync_cout << UCI::move(m, pos.is_chess960()) << ": " << cnt << sync_endl;
+            sync_cout << UCI::move(m, pos) << ": " << cnt << sync_endl;
     }
     return nodes;
   }
@@ -199,6 +199,12 @@ void MainThread::search() {
   if (rootMoves.empty())
   {
       rootMoves.emplace_back(MOVE_NONE);
+      if (Options["Protocol"] == "xboard")
+          sync_cout << (  !rootPos.checkers() ? "1/2-1/2 {Draw}"
+                        : rootPos.side_to_move() == BLACK ? "1-0 {White mates}"
+                                                          : "0-1 {Black mates}")
+                    << sync_endl;
+      else
       sync_cout << "info depth 0 score "
                 << UCI::value(rootPos.checkers() ? -VALUE_MATE : VALUE_DRAW)
                 << sync_endl;
@@ -237,7 +243,7 @@ void MainThread::search() {
       Time.availableNodes += Limits.inc[us] - Threads.nodes_searched();
 
   // Check if there are threads with a better score than main thread
-  Thread* bestThread = this;
+  bestThread = this;
   if (    Options["MultiPV"] == 1
       && !Limits.depth
       && !Skill(Options["Skill Level"]).enabled()
@@ -261,10 +267,17 @@ void MainThread::search() {
   if (bestThread != this)
       sync_cout << UCI::pv(bestThread->rootPos, bestThread->completedDepth, -VALUE_INFINITE, VALUE_INFINITE) << sync_endl;
 
-  sync_cout << "bestmove " << UCI::move(bestThread->rootMoves[0].pv[0], rootPos.is_chess960());
+  if (Options["Protocol"] == "xboard")
+  {
+      // Send move only when not in analyze mode and not at game end
+      if (!Options["UCI_AnalyseMode"] && rootMoves[0].pv[0] != MOVE_NONE)
+          sync_cout << "move " << UCI::move(bestThread->rootMoves[0].pv[0], rootPos) << sync_endl;
+      return;
+  }
+  sync_cout << "bestmove " << UCI::move(bestThread->rootMoves[0].pv[0], rootPos);
 
   if (bestThread->rootMoves[0].pv.size() > 1 || bestThread->rootMoves[0].extract_ponder_from_tt(rootPos))
-      std::cout << " ponder " << UCI::move(bestThread->rootMoves[0].pv[1], rootPos.is_chess960());
+      std::cout << " ponder " << UCI::move(bestThread->rootMoves[0].pv[1], rootPos);
 
   std::cout << sync_endl;
 }
@@ -866,9 +879,9 @@ namespace {
 
       ss->moveCount = ++moveCount;
 
-      if (rootNode && thisThread == Threads.main() && Time.elapsed() > 3000)
+      if (rootNode && thisThread == Threads.main() && Time.elapsed() > 3000 && Options["Protocol"] == "uci")
           sync_cout << "info depth " << depth / ONE_PLY
-                    << " currmove " << UCI::move(move, pos.is_chess960())
+                    << " currmove " << UCI::move(move, pos)
                     << " currmovenumber " << moveCount + thisThread->pvIdx << sync_endl;
       if (PvNode)
           (ss+1)->pv = nullptr;
@@ -1585,6 +1598,21 @@ string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) {
       if (ss.rdbuf()->in_avail()) // Not at first line
           ss << "\n";
 
+      if (Options["Protocol"] == "xboard")
+      {
+          ss << d << " "
+             << UCI::value(v) << " "
+             << elapsed / 10 << " "
+             << nodesSearched << " "
+             << rootMoves[i].selDepth << " "
+             << nodesSearched * 1000 / elapsed << " "
+             << tbHits << "\t";
+
+          for (Move m : rootMoves[i].pv)
+              ss << " " << UCI::move(m, pos);
+      }
+      else
+      {
       ss << "info"
          << " depth "    << d / ONE_PLY
          << " seldepth " << rootMoves[i].selDepth
@@ -1605,7 +1633,8 @@ string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) {
          << " pv";
 
       for (Move m : rootMoves[i].pv)
-          ss << " " << UCI::move(m, pos.is_chess960());
+          ss << " " << UCI::move(m, pos);
+      }
   }
 
   return ss.str();

src/thread.h

@@ -73,6 +73,7 @@ class Thread {
   CapturePieceToHistory captureHistory;
   ContinuationHistory contHistory;
   Score contempt;
+  Thread* bestThread; // to fetch best move when in XBoard mode
 };
 
 
@@ -107,9 +108,9 @@ struct ThreadPool : public std::vector<Thread*> {
 
   std::atomic_bool stop, ponder, stopOnPonderhit;
 
-private:
   StateListPtr setupStates;
 
+private:
   uint64_t accumulate(std::atomic<uint64_t> Thread::* member) const {
 
     uint64_t sum = 0;

src/types.h

@@ -188,6 +188,7 @@ enum Value : int {
   VALUE_DRAW      = 0,
   VALUE_KNOWN_WIN = 10000,
   VALUE_MATE      = 32000,
+  XBOARD_VALUE_MATE = 200000,
   VALUE_INFINITE  = 32001,
   VALUE_NONE      = 32002,
 

src/uci.cpp

@@ -31,6 +31,7 @@
 #include "timeman.h"
 #include "tt.h"
 #include "uci.h"
+#include "xboard.h"
 #include "syzygy/tbprobe.h"
 
 using namespace std;
@@ -198,6 +199,9 @@ void UCI::loop(int argc, char* argv[]) {
   for (int i = 1; i < argc; ++i)
       cmd += std::string(argv[i]) + " ";
 
+  // XBoard state machine
+  XBoard::StateMachine xboardStateMachine;
+
   do {
       if (argc == 1 && !getline(cin, cmd)) // Block here waiting for input or EOF
           cmd = "quit";
@@ -220,6 +224,18 @@ void UCI::loop(int argc, char* argv[]) {
       else if (token == "ponderhit")
           Threads.ponder = false; // Switch to normal search
 
+      else if (token == "uci" || token == "xboard")
+      {
+          Options["Protocol"] = token;
+          if (token == "uci")
+              sync_cout << "id name " << engine_info(true)
+                          << "\n" << Options
+                          << "\n" << token << "ok"  << sync_endl;
+      }
+
+      else if (Options["Protocol"] == "xboard")
+          xboardStateMachine.process_command(pos, token, is, states);
+
       else if (token == "uci")
           sync_cout << "id name " << engine_info(true)
                     << "\n"       << Options
@@ -256,6 +272,14 @@ string UCI::value(Value v) {
 
   stringstream ss;
 
+  if (Options["Protocol"] == "xboard")
+  {
+      if (abs(v) < VALUE_MATE - MAX_PLY)
+          ss << v * 100 / PawnValueEg;
+      else
+          ss << (v > 0 ? XBOARD_VALUE_MATE + VALUE_MATE - v + 1 : -XBOARD_VALUE_MATE - VALUE_MATE - v - 1) / 2;
+  } else
+
   if (abs(v) < VALUE_MATE - MAX_PLY)
       ss << "cp " << v * 100 / PawnValueEg;
   else
@@ -277,7 +301,7 @@ std::string UCI::square(Square s) {
 /// normal chess mode, and in e1h1 notation in chess960 mode. Internally all
 /// castling moves are always encoded as 'king captures rook'.
 
-string UCI::move(Move m, bool chess960) {
+string UCI::move(Move m, const Position& pos) {
 
   Square from = from_sq(m);
   Square to = to_sq(m);
@@ -288,7 +312,7 @@ string UCI::move(Move m, bool chess960) {
   if (m == MOVE_NULL)
       return "0000";
 
-  if (type_of(m) == CASTLING && !chess960)
+  if (type_of(m) == CASTLING && !pos.is_chess960())
       to = make_square(to > from ? FILE_G : FILE_C, rank_of(from));
 
   if (type_of(m) == SET_GATING_TYPE)
@@ -302,6 +326,8 @@ string UCI::move(Move m, bool chess960) {
 
   if (type_of(m) == PROMOTION)
       move += PieceToChar[make_piece(BLACK, promotion_type(m))];
+  else if (Options["Protocol"] == "xboard" && (pos.gates() & from))
+      move += PieceToChar[make_piece(BLACK, pos.gating_piece(from))];
 
   return move;
 }
@@ -315,8 +341,11 @@ Move UCI::to_move(const Position& pos, string& str) {
   if (str.length() == 5) // Junior could send promotion piece in uppercase
       str[4] = char(tolower(str[4]));
 
+  // allow optional gating suffix
+  string strNoSuffix = str.substr(0, 4);
+
   for (const auto& m : MoveList<LEGAL>(pos))
-      if (str == UCI::move(m, pos.is_chess960()))
+      if (str == UCI::move(m, pos) || strNoSuffix == UCI::move(m, pos))
           return m;
 
   return MOVE_NONE;

src/uci.h

@@ -23,6 +23,7 @@
 
 #include <map>
 #include <string>
+#include <vector>
 
 #include "types.h"
 
@@ -49,20 +50,22 @@ class Option {
   Option(OnChange = nullptr);
   Option(bool v, OnChange = nullptr);
   Option(const char* v, OnChange = nullptr);
+  Option(const char* v, const std::vector<std::string>& combo, OnChange = nullptr);
   Option(double v, int minv, int maxv, OnChange = nullptr);
-  Option(const char* v, const char *cur, OnChange = nullptr);
 
   Option& operator=(const std::string&);
   void operator<<(const Option&);
   operator double() const;
   operator std::string() const;
   bool operator==(const char*);
+  const std::string get_type() const;
 
 private:
   friend std::ostream& operator<<(std::ostream&, const OptionsMap&);
 
   std::string defaultValue, currentValue, type;
   int min, max;
+  std::vector<std::string> comboValues;
   size_t idx;
   OnChange on_change;
 };
@@ -71,7 +74,7 @@ void init(OptionsMap&);
 void loop(int argc, char* argv[]);
 std::string value(Value v);
 std::string square(Square s);
-std::string move(Move m, bool chess960);
+std::string move(Move m, const Position& pos);
 std::string pv(const Position& pos, Depth depth, Value alpha, Value beta);
 Move to_move(const Position& pos, std::string& str);