💾 Archived View for runjimmyrunrunyoufuckerrun.com › src › games › chessengines › crafty › root.c captured on 2021-12-17 at 13:26:06.
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#include "chess.h"
#include "data.h"
#include "epdglue.h"
/* last modified 04/21/15 */
/*
*******************************************************************************
* *
* RootMoveList() is used to set up the ply one move list. It is a more *
* accurate ordering of the move list than that done for plies deeper than *
* one. Briefly, Quiesce() is used to obtain the positional score plus the *
* expected gain/loss for pieces that can be captured. *
* *
*******************************************************************************
*/
void RootMoveList(int wtm) {
TREE *const tree = block[0];
unsigned mvp, *lastm, rmoves[256];
int temp, value;
#if !defined(NOEGTB)
int tb_value;
#endif
/*
************************************************************
* *
* If the position at the root is a draw, based on EGTB *
* results, we are going to behave differently. We will *
* extract the root moves that are draws, and toss the *
* losers out. Then, we will do a normal search on the *
* moves that draw to try and chose the drawing move that *
* gives our opponent the best chance to make an error. *
* This search will be done sans EGTB probes since we al- *
* ready know this is a draw at the root. We simply find *
* the best move (based on search/eval) that preserves the *
* draw. *
* *
************************************************************
*/
#if !defined(NOEGTB)
EGTB_draw = 0;
if (EGTBlimit && TotalAllPieces <= EGTBlimit &&
Castle(1, white) + Castle(1, black) == 0 &&
EGTBProbe(tree, 1, wtm, &tb_value)) {
if (swindle_mode && (tb_value == DrawScore(wtm)))
if ((wtm && Material > 0) || (!wtm && Material < 0))
EGTB_draw = 1;
}
#endif
/*
************************************************************
* *
* First, use GenerateMoves() to generate the set of legal *
* moves from the root position. *
* *
************************************************************
*/
lastm = GenerateCaptures(tree, 1, wtm, rmoves);
lastm = GenerateNoncaptures(tree, 1, wtm, lastm);
n_root_moves = lastm - rmoves;
for (mvp = 0; mvp < n_root_moves; mvp++)
root_moves[mvp].move = rmoves[mvp];
/*
************************************************************
* *
* Now make each move and use Quiesce() to analyze the *
* potential captures and return a minimax score. *
* *
* Special case: if this is an egtb draw at the root, *
* then this is where we cull the non-drawing moves by *
* doing an EGTB probe for each move. Any moves that lose *
* are left with a very bad sorting score to move them to *
* the end of the root move list. *
* *
************************************************************
*/
abort_search = 0;
for (mvp = 0; mvp < n_root_moves; mvp++) {
value = -4000000;
#if defined(TRACE)
if (trace_level >= 1) {
tree->curmv[1] = root_moves[mvp].move;
Trace(tree, 1, 0, wtm, -MATE, MATE, "RootMoves()", serial, HASH,
mvp + 1);
}
#endif
MakeMove(tree, 1, wtm, root_moves[mvp].move);
tree->nodes_searched++;
if (!Check(wtm))
do {
tree->curmv[1] = root_moves[mvp].move;
#if !defined(NOEGTB)
if (TotalAllPieces <= EGTBlimit && EGTB_draw &&
Castle(1, white) + Castle(1, black) == 0) {
temp = EGTBProbe(tree, 2, Flip(wtm), &tb_value);
if (temp && tb_value != DrawScore(Flip(wtm)))
break;
}
#endif
value = -Quiesce(tree, 2, Flip(wtm), -MATE, MATE, 0);
/*
************************************************************
* *
* Add in a bonus if this move is part of the previous *
* principal variation. It was good in the search, we *
* should try it first now. *
* *
************************************************************
*/
if ((Piece(root_moves[mvp].move) == Piece(last_pv.path[1]))
&& (From(root_moves[mvp].move) == From(last_pv.path[1]))
&& (To(root_moves[mvp].move) == To(last_pv.path[1]))
&& (Captured(root_moves[mvp].move) == Captured(last_pv.path[1]))
&& (Promote(root_moves[mvp].move) == Promote(last_pv.path[1])))
value += 2000000;
/*
************************************************************
* *
* Fudge the score for promotions so that promotion to a *
* queen is tried first. *
* *
************************************************************
*/
if (Promote(root_moves[mvp].move) &&
(Promote(root_moves[mvp].move) != queen))
value -= 50;
} while (0);
root_moves[mvp].path = tree->pv[1];
root_moves[mvp].path.pathv = value;
root_moves[mvp].status = 0;
root_moves[mvp].bm_age = 0;
UnmakeMove(tree, 1, wtm, root_moves[mvp].move);
}
/*
************************************************************
* *
* Sort the moves into order based on the scores returned *
* by Quiesce() which includes evaluation + captures. *
* *
************************************************************
*/
SortRootMoves();
/*
************************************************************
* *
* Trim the move list to eliminate those moves that hang *
* the king and are illegal. This also culls any non- *
* drawing moves when we are in the swindle-mode situation *
* and want to do a normal search but only on moves that *
* preserve the draw. *
* *
************************************************************
*/
for (; n_root_moves; n_root_moves--)
if (root_moves[n_root_moves - 1].path.pathv > -3000000)
break;
if (root_moves[0].path.pathv > 1000000)
root_moves[0].path.pathv -= 2000000;
/*
************************************************************
* *
* Debugging output to dump root move list and the stuff *
* used to sort them, for testing and debugging. *
* *
************************************************************
*/
if (display_options & 128) {
Print(128, "%d moves at root\n", n_root_moves);
Print(128, " score move/pv\n");
for (mvp = 0; mvp < n_root_moves; mvp++)
Print(128, "%10s %s\n", DisplayEvaluation(root_moves[mvp].path.pathv,
wtm), DisplayPath(tree, wtm, &root_moves[mvp].path));
}
/*
************************************************************
* *
* Finally, before we return the list of moves, we need to *
* set the values to an impossible negative value so that *
* as we sort the root move list after fail highs and lows *
* the un-searched moves won't pop to the top of the list. *
* *
************************************************************
*/
for (mvp = 1; mvp < n_root_moves; mvp++)
root_moves[mvp].path.pathv = -99999999;
return;
}