search_qsonly.cpp

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/*---------------------------------------------------------------------+
 * File: search_qsonly.cpp
 * Project: part of belofte - A Promising Chess Program
 * Author: yves
 * SPDX-License-Identifier: GPL-2.0-only
+----------------------------------------------------------------------*/
 
#include "belofte.h"
 
//-----------------------------------------------------------------------
 
SearchEvalPosOnly::SearchEvalPosOnly()
  : bSearchAlgorithm("StaticEval")
{
}
 
SearchEvalPosOnly::~SearchEvalPosOnly()
{
}
 
bScore SearchEvalPosOnly::CalcBestMove(bBoard& b)
{
  m_maxDepth = 1;
  bScore boardscore = RetrieveBoardEvaluation(b);
 
  bMoveList& ml = b.getMoveListRef();
  movenum_t n_moves = ml.getNumberOfMoves();
  DEBUG_sendInfoSearching(b, 0, "PV InitialPosScore", boardscore);
 
  for (movenum_t moveid = 1; moveid <= n_moves; moveid++) {
    CheckIfAbortingSearch();
    sendInfoCurrMove(b, 1, moveid);
    bBoard chldbrd(b, moveid);
    m_nonleafnodes++;
    bSearchScore chldscore(-Quiescence(chldbrd, -boardscore, 2), tScoreType::SC_CHILD);
    ml.setScoreOfMove(moveid, chldscore.getScore());
    DEBUG_sendInfoSearching(b, 0, "PV MoveValue", chldscore.getScore());
  }
 
  return SCORE_UNDEFINED;
}
 
//-----------------------------------------------------------------------
 
bScore SearchEvalPosOnly::Quiescence(bBoard& b, bScore nValueAtNullMove,
        depth_t const nDepth)
{
  if (nDepth > m_maxDepth) m_maxDepth = nDepth;
  bScore boardscore = RetrieveBoardEvaluation(b);
 
#if defined(_DEBUG)
  std::string izing = std::string(b.minimizing() > 0 ? "White" : "Black") + " to move";
#endif
 
  if (belofte::realScore(boardscore) > belofte::realScore(nValueAtNullMove)) {
    return DEBUG_returnInfoSearching(b, nDepth, izing + " st sc better than nullmove ("
            + belofte::to_string(nValueAtNullMove)
            + ") -- early cut off", boardscore);
  }
 
  bMoveList& ml = b.getMoveListRef();
  movenum_t n_moves = ml.generateMoves(b);
  if (!ml.getNumberOfQSMoves()) {
    // TODO: can be no moves position because of mate
    return DEBUG_returnInfoSearching(b, nDepth, "dead position (static eval)",
            boardscore);
  }
 
  DEBUG_sendInfoSearching(b, nDepth, izing + " (static eval)", boardscore);
 
  bSearchScore bestscore(boardscore, tScoreType::SC_BEST);
  for (movenum_t moveid = 1; moveid <= n_moves; moveid++) {
    if (ml[moveid].isNonSilent() || ml[moveid].isCheck()) {
      CheckIfAbortingSearch();
      sendInfoCurrMove(b, nDepth, moveid);
      bBoard chldbrd(b, moveid);
      m_nonleafnodes++;
      bSearchScore chldscore(-Quiescence(chldbrd, -nValueAtNullMove, nDepth + 1), tScoreType::SC_CHILD);
      ml.setScoreOfMove(moveid, chldscore.getScore());
      if (chldscore > bestscore) {
        b.setVariation(chldbrd);
        bestscore = chldscore.getScore();
        // TODO: first capture will always be better
        if (chldscore > belofte::realScore(nValueAtNullMove)) {
          return DEBUG_returnInfoSearching(b, nDepth, "better than nullmove ("
                  + belofte::to_string(nValueAtNullMove)
                  + ") -- cut-off", chldscore.getScore());
        }
      }
    }
  }
 
  return DEBUG_returnInfoSearching(b, nDepth, "(return best)", bestscore.getScore());
}
 
//-----------------------------------------------------------------------
 
// eof