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Use st->gamePly to store fullMoves

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This allow to retire do_setup_move() and also to simplify
draw detection logic becuase now we always have:

Min(st->rule50, st->gamePly) = st->rule50

This was already true when starting from starting position,
but now is true even when starting from a FEN string because
now we take in account fullmove number in counting gamePly so
that it is always.

st->rule50 <= st->gamePly

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba
2011-07-20 10:01:12 +02:00
parent 3d8140a541
commit 3185c36a65
4 changed files with 13 additions and 29 deletions
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28
src/position.cpp
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@@ -190,7 +190,11 @@ void Position::from_fen(const string& fenStr, bool isChess960) {
}
// 5-6. Halfmove clock and fullmove number
fen >> std::skipws >> st->rule50 >> fullMoves;
fen >> std::skipws >> st->rule50 >> st->gamePly;
// Convert from fullmove starting from 1 to ply starting from 0,
// handle also common incorrect FEN with fullmove = 0.
st->gamePly = Max(2 * (st->gamePly - 1), 0) + int(sideToMove == BLACK);
// Various initialisations
chess960 = isChess960;
@@ -310,7 +314,7 @@ const string Position::to_fen() const {
fen << '-';
fen << (ep_square() == SQ_NONE ? " -" : " " + square_to_string(ep_square()))
<< " " << st->rule50 << " " << fullMoves;
<< " " << st->rule50 << " " << 1 + (st->gamePly - int(sideToMove == BLACK)) / 2;
return fen.str();
}
@@ -759,23 +763,6 @@ bool Position::move_gives_check(Move m, const CheckInfo& ci) const {
}
/// Position::do_setup_move() makes a permanent move on the board. It should
/// be used when setting up a position on board. You can't undo the move.
void Position::do_setup_move(Move m, StateInfo& newSt) {
assert(move_is_ok(m));
// Update the number of full moves after black's move
if (sideToMove == BLACK)
fullMoves++;
do_move(m, newSt);
assert(is_ok());
}
/// Position::do_move() makes a move, and saves all information necessary
/// to a StateInfo object. The move is assumed to be legal. Pseudo-legal
/// moves should be filtered out before this function is called.
@@ -1528,7 +1515,6 @@ void Position::clear() {
castleRightsMask[sq] = ALL_CASTLES;
}
sideToMove = WHITE;
fullMoves = 1;
nodes = 0;
}
@@ -1670,7 +1656,7 @@ bool Position::is_draw() const {
// Draw by repetition?
if (!SkipRepetition)
{
int i = 4, e = Min(Min(st->gamePly, st->rule50), st->pliesFromNull);
int i = 4, e = Min(st->rule50, st->pliesFromNull);
if (i <= e)
{