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Use std library to sort moves

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Functional change due to the fact that now pick_best() is
stable, but should be no change in strenght.

Example code and ideas by Rein Halbersma.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba
2011-07-14 12:12:49 +01:00
parent 0cfb30e5be
commit fbdabe2975
5 changed files with 36 additions and 82 deletions
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27
src/movepick.cpp
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@@ -18,6 +18,7 @@
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <algorithm>
#include <cassert>
#include "movegen.h"
@@ -49,6 +50,19 @@ namespace {
const uint8_t QsearchWithoutChecksTable[] = { PH_TT_MOVE, PH_QCAPTURES, PH_STOP };
const uint8_t QsearchRecapturesTable[] = { PH_TT_MOVE, PH_QRECAPTURES, PH_STOP };
const uint8_t ProbCutTable[] = { PH_TT_MOVE, PH_GOOD_PROBCUT, PH_STOP };
// Unary predicate used by std::partition to split positive scores from ramining
// ones so to sort separately the two sets, and with the second sort delayed.
inline bool has_positive_score(const MoveStack& move) { return move.score > 0; }
// Picks and pushes to the front the best move in range [firstMove, lastMove),
// it is faster then sorting all the moves in advance when moves are few, as
// normally are the possible captures.
inline MoveStack* pick_best(MoveStack* firstMove, MoveStack* lastMove)
{
std::swap(*firstMove, *std::max_element(firstMove, lastMove));
return firstMove;
}
}
/// Constructors for the MovePicker class. As arguments we pass information
@@ -164,14 +178,15 @@ void MovePicker::go_next_phase() {
case PH_NONCAPTURES_1:
lastNonCapture = lastMove = generate<MV_NON_CAPTURE>(pos, moves);
score_noncaptures();
sort_moves(moves, lastNonCapture, &lastMove);
lastMove = std::partition(curMove, lastMove, has_positive_score);
sort<MoveStack>(curMove, lastMove);
return;
case PH_NONCAPTURES_2:
curMove = lastMove;
lastMove = lastNonCapture;
if (depth >= 3 * ONE_PLY)
insertion_sort<MoveStack>(curMove, lastMove);
sort<MoveStack>(curMove, lastMove);
return;
case PH_BAD_CAPTURES:
@@ -306,7 +321,7 @@ Move MovePicker::get_next_move() {
break;
case PH_GOOD_CAPTURES:
move = pick_best(curMove++, lastMove).move;
move = pick_best(curMove++, lastMove)->move;
if (move != ttMove)
{
assert(captureThreshold <= 0); // Otherwise we must use see instead of see_sign
@@ -324,7 +339,7 @@ Move MovePicker::get_next_move() {
break;
case PH_GOOD_PROBCUT:
move = pick_best(curMove++, lastMove).move;
move = pick_best(curMove++, lastMove)->move;
if ( move != ttMove
&& pos.see(move) > captureThreshold)
return move;
@@ -349,12 +364,12 @@ Move MovePicker::get_next_move() {
break;
case PH_BAD_CAPTURES:
move = pick_best(curMove++, lastMove).move;
move = pick_best(curMove++, lastMove)->move;
return move;
case PH_EVASIONS:
case PH_QCAPTURES:
move = pick_best(curMove++, lastMove).move;
move = pick_best(curMove++, lastMove)->move;
if (move != ttMove)
return move;
break;