-
Notifications
You must be signed in to change notification settings - Fork 10
/
Copy pathsearch.c
2062 lines (1678 loc) · 44.8 KB
/
search.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
/*
Sjeng - a chess variants playing program
Copyright (C) 2000-2001 Gian-Carlo Pascutto
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
File: search.c
Purpose: contains functions related to the recursive search
*/
#include "sjeng.h"
#include "extvars.h"
#include "protos.h"
#include "limits.h"
unsigned long FH, FHF;
unsigned long razor_drop, razor_material, drop_cuts, ext_recap, ext_onerep, ext_check;
char true_i_depth;
int bestmovenum;
int ugly_ep_hack;
char postpv[STR_BUFF];
char searching_move[20];
int moveleft;
int movetotal;
int legals;
int failed;
int extendedtime;
int tradefreely;
int s_threat;
unsigned long rootnodecount[MOVE_BUFF];
bool checks[PV_BUFF];
#define KINGCAP 50000
#define NONE 0
#define SINGLE 1
void order_moves (move_s moves[], long int move_ordering[], long int see_values[], int num_moves, int best) {
int promoted, captured;
int i, from, target, seev;
/* fill the move ordering array: */
/* if searching the pv, give it the highest move ordering, and if not, rely
on the other heuristics: */
if (searching_pv) {
searching_pv = FALSE;
for (i = 0; i < num_moves; i++) {
from = moves[i].from;
target = moves[i].target;
promoted = moves[i].promoted;
captured = moves[i].captured;
/* give captures precedence in move ordering, and order captures by
material gain */
if (captured != npiece)
{
seev = see(ToMove, target, from);
if (seev >= -50)
move_ordering[i] = 50000 + seev;
else
move_ordering[i] = seev;
see_values[i] = seev;
}
else
move_ordering[i] = 0;
/* make the pv have highest move ordering: */
if (from == pv[1][ply].from
&& target == pv[1][ply].target
&& promoted == pv[1][ply].promoted) {
searching_pv = TRUE;
move_ordering[i] = INF;
if (captured != npiece)
see_values[i] = see(ToMove, target, from);
}
else if ((best != -1) && (best != -2) && (i == best))
{
move_ordering[i] = INF;
if (captured != npiece)
see_values[i] = see(ToMove, target, from);
}
else if (best == -2)
{
/* we have an iterative deepening move */
if (from == pv[ply+1][ply+1].from
&& target == pv[ply+1][ply+1].target
&& promoted == pv[ply+1][ply+1].promoted)
{
move_ordering[i] = INF;
}
}
/* heuristics other than pv (no need to use them on the pv move - it is
already ordered highest) */
else
{
if (ply != 1 || i_depth < 2)
{
/* add the history heuristic bonus: */
move_ordering[i] += (history_h[from][target]>>i_depth);
/* add the killer move heuristic bonuses: */
if (from == killer1[ply].from && target == killer1[ply].target
&& promoted == killer1[ply].promoted)
move_ordering[i] += 10000;
else if (from == killer2[ply].from && target == killer2[ply].target
&& promoted == killer2[ply].promoted)
move_ordering[i] += 5000;
else if (from == killer3[ply].from && target == killer3[ply].target
&& promoted == killer3[ply].promoted)
move_ordering[i] += 2500;
}
else
{
if ((nodes / 100) > INF)
{
move_ordering[i] = rootnodecount[i] / 1000;
}
else
{
move_ordering[i] = rootnodecount[i] / 100;
}
}
}
}
}
/* if not searching the pv: */
else {
for (i = 0; i < num_moves; i++) {
from = moves[i].from;
target = moves[i].target;
promoted = moves[i].promoted;
captured = moves[i].captured;
/* give captures precedence in move ordering, and order captures by
material gain */
if ((best != -1) && (i == best))
{
move_ordering[i] = INF;
/* make sure we have SEE data */
if (captured != npiece)
see_values[i] = see(ToMove, target, from);
}
else if (best == -2)
{
/* we have an iterative deepening move */
if (from == pv[ply+1][ply+1].from
&& target == pv[ply+1][ply+1].target
&& promoted == pv[ply+1][ply+1].promoted)
{
move_ordering[i] = INF;
if (captured != npiece)
see_values[i] = see(ToMove, target, from);
}
}
else if (captured != npiece)
{
seev = see(ToMove, target, from);
if (seev >= -50)
move_ordering[i] = 50000 + seev;
else
move_ordering[i] = seev;
see_values[i] = seev;
}
else
move_ordering[i] = 0;
/* heuristics other than pv */
/* add the history heuristic bonus: */
move_ordering[i] += (history_h[from][target]>>i_depth);
/* add the killer move heuristic bonuses: */
if (from == killer1[ply].from && target == killer1[ply].target
&& promoted == killer1[ply].promoted)
move_ordering[i] += 10000;
else if (from == killer2[ply].from && target == killer2[ply].target
&& promoted == killer2[ply].promoted)
move_ordering[i] += 5000;
else if (from == killer3[ply].from && target == killer3[ply].target
&& promoted == killer3[ply].promoted)
move_ordering[i] += 2500;
}
}
}
void perft (int depth) {
move_s moves[MOVE_BUFF];
int num_moves, i;
int ic;
//ep_temp = ep_square;
num_moves = 0;
/* return if we are at the maximum depth: */
if (!depth) {
raw_nodes++;
return;
}
/* generate the move list: */
gen (&moves[0]);
num_moves = numb_moves;
ic = in_check();
/* loop through the moves at the current depth: */
for (i = 0; i < num_moves; i++) {
make (&moves[0], i);
/* check to see if our move is legal: */
if (check_legal (&moves[0], i, ic)) {
/* go deeper into the tree recursively, increasing the indent to
create the "tree" effect: */
perft (depth-1);
}
/* unmake the move to go onto the next: */
unmake (&moves[0], i);
}
//ep_square = ep_temp;
}
long int qsearch (int alpha, int beta, int depth) {
/* perform a quiscense search on the current node using alpha-beta with
negamax search */
move_s moves[MOVE_BUFF];
int num_moves, i, j;
long int score = -INF, standpat,
move_ordering[MOVE_BUFF],
see_values[MOVE_BUFF];
bool legal_move, no_moves = TRUE;
int sbest, best_score, best, delta, bound;
int originalalpha;
long int oldtime;
int seev;
pv_length[ply] = ply;
/* before we do anything, see if we're out of time: */
if (!(nodes & 8191))
{
if (interrupt())
{
time_exit = TRUE;
return 0;
}
else if (((rdifftime (rtime (), start_time) >= time_for_move)) && (i_depth > 1))
{
if (failed == 1 && !extendedtime
&& !fixed_time
&& !go_fast
&& Variant != Bughouse
&& (time_left > max(time_for_move*4, 1000)))
{
extendedtime = 1;
oldtime = time_for_move;
time_for_move += allocate_time();
printf("Extended from %ld to %ld, time left %ld\n", oldtime,
time_for_move,
time_left);
}
else
{
time_exit = TRUE;
return 0;
}
}
}
/* return our score if we're at a leaf node: */
if (depth <= 0 || ply > maxdepth)
{
/* remove leafcounting effect */
qnodes--;
nodes--;
score = eval ();
return score;
}
originalalpha = alpha;
switch (QProbeTT(&bound, alpha, beta, &best))
{
case EXACT:
return bound;
break;
case UPPER:
if (bound <= alpha)
return bound;
if (bound < beta)
beta = bound;
break;
case LOWER:
if (bound >= beta)
return bound;
if (bound > alpha)
alpha = bound;
break;
case DUMMY:
break;
case HMISS:
best = -1;;
break;
};
standpat = eval ();
if (standpat >= beta) {
/* rem check this */
QStoreTT(standpat, originalalpha, beta, 500);
return standpat;
}
else if (standpat > alpha) {
alpha = standpat;
}
sbest = -1;
best_score = -INF;
num_moves = 0;
delta = alpha-150-standpat;
/* generate and order moves: */
gen (&moves[0]);
num_moves = numb_moves;
if (kingcap) return KINGCAP;
order_moves (&moves[0], &move_ordering[0], &see_values[0], num_moves, best);
/* loop through the moves at the current node: */
while (remove_one (&i, &move_ordering[0], num_moves)) {
legal_move = FALSE;
seev = see_values[i];
if (!moves[i].promoted && ((seev < delta) || (seev < 0)))
continue;
make (&moves[0], i);
score = -qsearch (-beta, -alpha, depth-1);
if (score != -KINGCAP)
{
nodes++;
qnodes++;
legal_move = TRUE;
no_moves = FALSE;
};
unmake (&moves[0], i);
if(score > best_score && legal_move)
{
best_score = score;
};
/* check our current score vs. alpha: */
if (score > alpha && legal_move)
{
/* don't update the history heuristic scores here, since depth is messed
up when qsearch is called */
best = i;
/* try for an early cutoff: */
if (score >= beta)
{
QStoreTT(score, originalalpha, beta, i);
return score;
}
alpha = score;
/* update the pv: */
pv[ply][ply] = moves[i];;
for (j = ply+1; j < pv_length[ply+1]; j++)
pv[ply][j] = pv[ply+1][j];
pv_length[ply] = pv_length[ply+1];
}
}
/* we don't check for mate / stalemate here, because without generating all
of the moves leading up to it, we don't know if the position could have
been avoided by one side or not */
if (no_moves)
{
/* we tried all moves and none were good...sack to alpha */
return standpat;
}
else
{
QStoreTT(alpha, originalalpha, beta, best);
return alpha;
}
}
bool remove_one (int *marker, long int move_ordering[], int num_moves) {
/* a function to give pick the top move order, one at a time on each call.
Will return TRUE while there are still moves left, FALSE after all moves
have been used */
int i, best = -INF;
*marker = -INF;
for (i = 0; i < num_moves; i++) {
if (move_ordering[i] > best) {
*marker = i;
best = move_ordering[i];
}
}
if (*marker > -INF) {
move_ordering[*marker] = -INF;
return TRUE;
}
else {
return FALSE;
}
}
long int search (int alpha, int beta, int depth, int is_null) {
/* search the current node using alpha-beta with negamax search */
move_s moves[MOVE_BUFF];
int num_moves, i, j;
long int score = -INF, move_ordering[MOVE_BUFF], see_values[MOVE_BUFF];
bool no_moves, legal_move;
int bound, threat, donull, best, sbest, best_score, old_ep;
bool incheck, first;
int extend, fscore, fmax, selective;
move_s kswap;
int ksswap;
int originalalpha;
int afterincheck;
int legalmoves;
int dropcut;
long int oldtime;
int egscore;
static const int rc_index[14] = {0,1,1,2,2,5,5,3,3,4,4,2,2,0};
/* before we do anything, see if we're out of time: */
if (!(nodes & 8191)) {
if (interrupt())
{
time_exit = TRUE;
return 0;
}
else if (((rdifftime (rtime (), start_time) >= time_for_move)) && (i_depth > 1))
{
if (failed == 1 && !extendedtime
&& !fixed_time
&& !go_fast
&& Variant != Bughouse
&& (time_left > max(time_for_move*4, 1000)))
{
extendedtime = 1;
oldtime = time_for_move;
time_for_move += allocate_time();
printf("Extended from %ld to %ld, time left %ld\n", oldtime,
time_for_move,
time_left);
}
else
{
time_exit = TRUE;
return 0;
}
}
}
originalalpha = alpha;
fmax = -INF;
threat = 0;
extend = 0;
pv_length[ply] = ply;
if (is_draw ())
{
return 0;
}
if ((path[ply-1].captured != npiece || ply == 2))
{
if (piece_count <= 3 && (Variant == Suicide) && SEGTB)
{
EGTBProbes++;
egscore = egtb(white_to_move);
if (egscore != -128)
{
EGTBHits++;
if (egscore < 0)
{
return -INF+(129+egscore);
}
else if (egscore > 0)
{
return INF-(129-egscore);
}
else if (egscore == 0)
return 0;
}
}
}
incheck = checks[ply];
/* perform check extensions if we haven't gone past maxdepth: */
if (ply < maxdepth+1 && incheck && ((ply <= i_depth*2) || (depth == 0)))
{
depth++;
ext_check++;
extend++;
}
else if ((ply < maxdepth+1) && (ply > 2) && (ply < (i_depth*2))
&& (depth <= 2)
&& cfg_recap
&& (path[ply-1].captured != 13)
&& (rc_index[path[ply-1].captured] == rc_index[path[ply-2].captured]))
{
depth++;
ext_recap++;
extend++;
}
/* try to find a stable position before passing the position to eval (): */
if (depth <= 0 || ply >= maxdepth)
{
if (Variant != Suicide && Variant != Losers)
{
captures = TRUE;
score = qsearch (alpha, beta, maxdepth);
captures = FALSE;
return score;
}
else
{
if (Variant == Suicide)
{
return suicide_eval();
}
else if (Variant == Losers)
{
i = losers_eval();
if (abs(i) == INF)
{
return ((i > 0) ? INF-ply : -INF+ply);
}
else
{
return i;
}
}
}
}
num_moves = 0;
no_moves = TRUE;
switch (ProbeTT(&bound, alpha, beta, &best, &threat, &donull, depth))
{
case EXACT:
return bound;
break;
case UPPER:
if (bound <= alpha)
return bound;
if (bound < beta)
beta = bound;
best = -1;
break;
case LOWER:
if (bound >= beta)
return bound;
if (bound > alpha)
alpha = bound;
break;
case DUMMY:
break;
case HMISS:
best = -1;
threat = FALSE;
break;
};
if (best == 500) best = -1;
sbest = -1;
best_score = -INF;
old_ep = ep_square;
legalmoves = 0;
if (Variant == Losers)
{
i = losers_eval();
if (abs(i) == INF)
{
return (i > 0) ? i-ply : i+ply;
}
captures = TRUE;
gen (&moves[0]);
num_moves = numb_moves;
captures = FALSE;
if (num_moves)
{
for (i = 0; i < num_moves; i++)
{
make(&moves[0], i);
if (check_legal(&moves[0], i, incheck))
{
legalmoves++;
}
unmake(&moves[0], i);
}
}
if (!legalmoves)
{
captures = FALSE;
gen(&moves[0]);
num_moves = numb_moves;
};
legalmoves = 0;
}
if ((is_null == NONE)
&& ((phase != Endgame) || ((phase == Endgame) && (depth <= 6)))
&& !incheck && donull && !searching_pv
&& (threat == FALSE)
&& (((Variant != Suicide) && (Variant != Losers))
|| (Variant == Losers && moves[0].captured == npiece)))
{
ep_square = 0;
white_to_move ^= 1;
ply++;
fifty++;
hash ^= 0xDEADBEEF;
/* use R=1 cos R=2 is too dangerous for our ply depths */
if (Variant != Normal && Variant != Losers)
score = -search(-beta, -beta+1, ((depth > 3) ? depth-2-1 : depth-1-1), SINGLE);
else
{
if (depth > 11)
score = -search(-beta, -beta+1, depth-4-1, SINGLE);
else if (depth > 6)
score = -search(-beta, -beta+1, depth-3-1, SINGLE);
else
score = -search(-beta, -beta+1, depth-2-1, SINGLE);
};
hash ^= 0xDEADBEEF;
fifty--;
ply--;
white_to_move ^= 1;
ep_square = old_ep;
if (time_exit) return 0;
NTries++;
if (score >= beta)
{
NCuts++;
StoreTT(score, alpha, beta, 500, 0, depth);
return score;
}
else if (score < -INF+100)
{
threat = TRUE;
TExt++;
depth++;
extend++;
ext_onerep++;
}
}
else if (threat == TRUE)
{
TExt++;
depth++;
extend++;
ext_onerep++;
}
score = -INF;
first = TRUE;
selective = 0;
if (phase != Endgame && (Variant != Suicide) && cfg_futprune)
{
fscore = (white_to_move ? Material : -Material) + 900;
if (!extend && depth == 3 && fscore <= alpha)
depth = 2;
fscore = (white_to_move ? Material : -Material) + 500;
if (!extend && depth == 2 && fscore <= alpha)
{
selective = 1;
best_score = fmax = fscore;
}
fscore = (white_to_move ? Material : -Material) + ((Variant == Normal) ? 150 : 200);
if (!extend && depth == 1 && fscore <= alpha)
{
selective = 1;
best_score = fmax = fscore;
}
}
if (Variant != Losers)
{
/* generate and order moves: */
gen (&moves[0]);
num_moves = numb_moves;
}
if ((Variant == Suicide) && num_moves == 1) depth++;
else if ((Variant == Losers) && legalmoves == 1) depth++;
if (num_moves > 0)
{
order_moves (&moves[0], &move_ordering[0], &see_values[0], num_moves, best);
/* loop through the moves at the current node: */
while (remove_one (&i, &move_ordering[0], num_moves)) {
make (&moves[0], i);
legal_move = FALSE;
hash_history[move_number+ply-1] = hash;
path[ply-1] = moves[i];
//old_ep = ep_square;
extend = 0; /* dont extend twice */
/* go deeper if it's a legal move: */
if (check_legal (&moves[0], i, incheck)) {
afterincheck = f_in_check(&moves[0], i);
checks[ply] = afterincheck;
if (!afterincheck && ((Variant == Normal)
|| (Variant == Suicide)
|| (Variant == Losers)) && (depth < 3) &&
(((board[moves[i].target] == wpawn) && (rank(moves[i].target) >= 6))
|| ((board[moves[i].target] == bpawn) && (rank(moves[i].target) <= 3))))
{
extend++;
};
dropcut = 0;
/* Razoring of uninteresting drops */
if ((moves[i].from == 0)
&& (depth > 1) /* more than pre-frontier nodes */
&& (afterincheck == 0) /* not a contact checking move */
&& (incheck == 0) /* not a check evasion */
&& !searching_pv
&& cfg_razordrop
)
{ razor_drop++; extend--;}
else
{
if ((moves[i].from == 0) && (depth == 1) && (incheck == 0) && cfg_cutdrop)
{
if (white_to_move)
{
dropcut = (calc_attackers(moves[i].target, 1)
- calc_attackers(moves[i].target, 0)) > 0;
if (dropcut) drop_cuts++;
}
else
{
dropcut = (calc_attackers(moves[i].target, 0)
- calc_attackers(moves[i].target, 1)) > 0;
if (dropcut) drop_cuts++;
}
}
}
if (!dropcut && (!selective || (afterincheck != 0)
|| (fmax + ((abs(material[moves[i].captured]) *
((Variant == Normal || Variant == Losers)?1:2)
)) > alpha)
|| (moves[i].promoted)))
{
/* we only count the nodes we actually examine */
nodes++;
if (first == TRUE)
{
score = -search (-beta, -alpha, depth+extend-1, NONE);
FULL++;
}
else
{
score = -search (-alpha-1, -alpha, depth+extend-1, NONE);
PVS++;
if (score > best_score && !time_exit && score != -KINGCAP)
{
if ((score > alpha) && (score < beta))
{
score = -search(-beta, -score, depth+extend-1, NONE);
// ep_square = old_ep;
PVSF++;
if (score > best_score) best_score = score;
}
else
best_score = score;
}
}
legal_move = TRUE;
}
else
razor_material++;
legalmoves++;
no_moves = FALSE;
}
if (score > best_score && legal_move)
{
best_score = score;
};
unmake (&moves[0], i);
/* return if we've run out of time: */
if (time_exit) return 0;
/* check our current score vs. alpha: */
if (score > alpha && legal_move) {
/* try for an early cutoff: */
if (score >= beta) {
/* update the history heuristic since we have a cutoff: */
history_h[moves[i].from][moves[i].target] += depth * depth;
if (moves[i].captured == npiece)
{
/* we have a cutoff, so update our killers: */
/* first, check whether it matches one of the known killers */
if (moves[i].from == killer1[ply].from && moves[i].target ==
killer1[ply].target && moves[i].promoted == killer1[ply].promoted)
{
killer_scores[ply]++;
}
else if (moves[i].from == killer2[ply].from && moves[i].target ==
killer2[ply].target && moves[i].promoted == killer2[ply].promoted)
{
killer_scores2[ply]++;
if (killer_scores2[ply] > killer_scores[ply])
{
kswap = killer1[ply];
killer1[ply] = killer2[ply];
killer2[ply] = kswap;
ksswap = killer_scores[ply];
killer_scores[ply] = killer_scores2[ply];
killer_scores2[ply] = ksswap;
}
}
else if (moves[i].from == killer3[ply].from && moves[i].target ==
killer3[ply].target && moves[i].promoted == killer3[ply].promoted)
{
killer_scores3[ply]++;
if (killer_scores3[ply] > killer_scores2[ply])
{
kswap = killer2[ply];
killer2[ply] = killer3[ply];
killer3[ply] = kswap;
ksswap = killer_scores2[ply];
killer_scores2[ply] = killer_scores3[ply];
killer_scores3[ply] = ksswap;
}
}
/* if not, replace killer3 */
else
{
killer_scores3[ply] = 1;
killer3[ply] = moves[i];
}
}
if (first == TRUE) FHF++;
FH++;
StoreTT(score, originalalpha, beta, i, threat, depth);
return score;
}
alpha = score;
sbest = i;
/* update the pv: */
pv[ply][ply] = moves[i];
for (j = ply+1; j < pv_length[ply+1]; j++)
pv[ply][j] = pv[ply+1][j];
pv_length[ply] = pv_length[ply+1];
}
if (legal_move)
first = FALSE;