void InitCaptures(POS *p, MOVES *m) {
m->phase = 0;
m->p = p;
m->last = GenerateCaptures(m->p, m->move);
ScoreCaptures(m);
m->next = m->move;
}
/*
********************************************************************************
* *
* Ponder() is the driver for "pondering" (thinking on the opponent's time.) *
* its operation is simple: find a predicted move by (a) taking the second *
* move from the principal variation, or (b) call lookup to see if it finds *
* a suggested move from the transposition table. then, make this move and *
* do a search from the resulting position. while pondering, one of three *
* things can happen: (1) a move is entered, and it matches the predicted *
* move. we then switch from pondering to thinking and search as normal; *
* (2) a move is entered, but it does not match the predicted move. we then *
* abort the search, unmake the pondered move, and then restart with the move *
* entered. (3) a command is entered. if it is a simple command, it can be *
* done without aborting the search or losing time. if not, we abort the *
* search, execute the command, and then attempt to restart pondering if the *
* command didn't make that impossible. *
* *
********************************************************************************
*/
int Ponder(int wtm)
{
int dummy=0, i, *n_ponder_moves, *mv;
/*
----------------------------------------------------------
| |
| first, let's check to see if pondering is allowed, or |
| if we should avoid pondering on this move since it is |
| the first move of a game, or if the game is over, or |
| "force" mode is active, or there is input in the queue |
| that needs to be read and processed. |
| |
----------------------------------------------------------
*/
if (!ponder || force || over || CheckInput()) return(0);
/*
----------------------------------------------------------
| |
| if we don't have a predicted move to ponder, try two |
| sources: (1) look up the current position in the |
| transposition table and see if it has a suggested best |
| move; (2) do a short tree search to calculate a move |
| that we should ponder. |
| |
----------------------------------------------------------
*/
strcpy(hint,"none");
if (!ponder_move) {
(void) LookUp(0,0,wtm,&dummy,&dummy);
if (hash_move[0]) ponder_move=hash_move[0];
}
if (!ponder_move) {
TimeSet(puzzle);
if (time_limit < 3) return(0);
puzzling=1;
position[1]=position[0];
printf(" puzzling over a move to ponder.\n");
last_pv.path_length=0;
last_pv.path_iteration_depth=0;
for (i=0;i<MAXPLY;i++) {
killer_move1[i]=0;
killer_move2[i]=0;
killer_count1[i]=0;
killer_count2[i]=0;
}
(void) Iterate(wtm,puzzle,0);
for (i=0;i<MAXPLY;i++) {
killer_move1[i]=0;
killer_move2[i]=0;
killer_count1[i]=0;
killer_count2[i]=0;
}
puzzling=0;
if (pv[0].path_length) ponder_move=pv[0].path[1];
if (!ponder_move) return(0);
for (i=1;i<(int) pv[0].path_length-1;i++) last_pv.path[i]=pv[0].path[i+1];
last_pv.path_length=pv[0].path_length-1;
last_pv.path_iteration_depth=0;
if (!ValidMove(1,wtm,ponder_move)) {
ponder_move=0;
return(0);
}
}
/*
----------------------------------------------------------
| |
| display the move we are going to "ponder". |
| |
----------------------------------------------------------
*/
if (wtm)
printf("White(%d): %s [pondering]\n",
move_number,OutputMove(&ponder_move,0,wtm));
else
printf("Black(%d): %s [pondering]\n",
move_number,OutputMove(&ponder_move,0,wtm));
sprintf(hint,"%s",OutputMove(&ponder_move,0,wtm));
if (post) printf("Hint: %s\n",hint);
/*
----------------------------------------------------------
| |
| set the ponder move list and eliminate illegal moves. |
| |
----------------------------------------------------------
*/
n_ponder_moves=GenerateCaptures(0, wtm, ponder_moves);
num_ponder_moves=GenerateNonCaptures(0, wtm, n_ponder_moves)-ponder_moves;
for (mv=ponder_moves;mv<ponder_moves+num_ponder_moves;mv++) {
MakeMove(0, *mv, wtm);
if (Check(wtm)) {
UnMakeMove(0, *mv, wtm);
*mv=0;
}
else UnMakeMove(0, *mv, wtm);
}
/*
----------------------------------------------------------
| |
| now, perform an iterated search, but with the special |
| "pondering" flag set which changes the time controls |
| since there is no need to stop searching until the |
| opponent makes a move. |
| |
----------------------------------------------------------
*/
MakeMove(0,ponder_move,wtm);
if (Rule50Moves(1)==90 || Rule50Moves(1)==91) ClearHashTables();
last_opponent_move=ponder_move;
if (ChangeSide(wtm))
*rephead_w++=HashKey;
else
*rephead_b++=HashKey;
if (RepetitionDraw(wtm)) printf("game is a draw by repetition\n");
if (whisper) strcpy(whisper_text,"n/a");
thinking=0;
pondering=1;
(void) Iterate(ChangeSide(wtm),think,0);
pondering=0;
thinking=0;
if (ChangeSide(wtm))
rephead_w--;
else
rephead_b--;
last_opponent_move=0;
UnMakeMove(0,ponder_move,wtm);
/*
----------------------------------------------------------
| |
| search completed. the possible return values are: |
| |
| (0) no pondering was done, period. |
| |
| (1) pondering was done, opponent made the predicted |
| move, and we searched until time ran out in a |
| normal manner. |
| |
| (2) pondering was done, but the ponder search |
| terminated due to either finding a mate, or the |
| maximum search depth was reached. the result of |
| this ponder search are valid, but only if the |
| opponent makes the correct (predicted) move. |
| |
| (3) pondering was done, but the opponent either made |
| a different move, or entered a command that has to |
| interrupt the pondering search before the command |
| (or move) can be processed. this forces Main() to |
| avoid reading in a move/command since one has been |
| read into the command buffer already. |
| |
----------------------------------------------------------
*/
if (made_predicted_move) return(1);
if (abort_search) return(3);
return(2);
}
/*
********************************************************************************
* *
* Ponder() is the driver for "pondering" (thinking on the opponent's time.) *
* its operation is simple: find a predicted move by (a) taking the second *
* move from the principal variation, or (b) call lookup to see if it finds *
* a suggested move from the transposition table. then, make this move and *
* do a search from the resulting position. while pondering, one of three *
* things can happen: (1) a move is entered, and it matches the predicted *
* move. we then switch from pondering to thinking and search as normal; *
* (2) a move is entered, but it does not match the predicted move. we then *
* abort the search, unmake the pondered move, and then restart with the move *
* entered. (3) a command is entered. if it is a simple command, it can be *
* done without aborting the search or losing time. if not, we abort the *
* search, execute the command, and then attempt to restart pondering if the *
* command didn't make that impossible. *
* *
********************************************************************************
*/
int Ponder(int wtm)
{
int dummy=0, i, *n_ponder_moves;
/*
----------------------------------------------------------
| |
| if we don't have a predicted move to ponder, try two |
| sources: (1) look up the current position in the |
| transposition table and see if it has a suggested best |
| move; (2) do a short tree search to calculate a move |
| that we should ponder. |
| |
----------------------------------------------------------
*/
ponder_completed=0;
if (!ponder_move) {
(void) LookUp(0,0,wtm,&dummy,dummy);
if (hash_move[0]) ponder_move=hash_move[0];
}
if (!ponder_move) {
TimeSet(puzzle);
if (time_limit < 3) return(0);
puzzling=1;
position[1]=position[0];
Print(2," puzzling over a move to ponder.\n");
last_pv.path_length=0;
last_pv.path_iteration_depth=0;
for (i=0;i<MAXPLY;i++) {
killer_move1[i]=0;
killer_move2[i]=0;
killer_count1[i]=0;
killer_count2[i]=0;
}
(void) Iterate(wtm,puzzle);
for (i=0;i<MAXPLY;i++) {
killer_move1[i]=0;
killer_move2[i]=0;
killer_count1[i]=0;
killer_count2[i]=0;
}
puzzling=0;
if (pv[0].path_length) ponder_move=pv[0].path[1];
if (!ponder_move) return(0);
for (i=1;i<(int) pv[0].path_length-1;i++) last_pv.path[i]=pv[0].path[i+1];
last_pv.path_length=pv[0].path_length-1;
last_pv.path_iteration_depth=0;
if (!ValidMove(1,wtm,ponder_move)) {
printf("puzzle returned an illegal move!\n");
DisplayChessMove("move= ",ponder_move);
ponder_move=0;
return(0);
}
}
if (!ponder_move) {
strcpy(hint,"none");
return(0);
}
/*
----------------------------------------------------------
| |
| display the move we are going to "ponder". |
| |
----------------------------------------------------------
*/
if (wtm)
Print(2,"White(%d): %s [pondering]\n",
move_number,OutputMove(&ponder_move,0,wtm));
else
Print(2,"Black(%d): %s [pondering]\n",
move_number,OutputMove(&ponder_move,0,wtm));
sprintf(hint,"%s",OutputMove(&ponder_move,0,wtm));
n_ponder_moves=GenerateCaptures(0, wtm, ponder_moves);
num_ponder_moves=GenerateNonCaptures(0, wtm, n_ponder_moves)-ponder_moves;
/*
----------------------------------------------------------
| |
| now, perform an iterated search, but with the special |
| "pondering" flag set which changes the time controls |
| since there is no need to stop searching until the |
| opponent makes a move. |
| |
----------------------------------------------------------
*/
MakeMove(0,ponder_move,wtm);
if (Rule50Moves(1)==90 || Rule50Moves(1)==91) ClearHashTables();
last_opponent_move=ponder_move;
if (ChangeSide(wtm))
*rephead_w++=HashKey;
else
*rephead_b++=HashKey;
if (RepetitionDraw(wtm)) Print(0,"game is a draw by repetition\n");
if (whisper) strcpy(whisper_text,"n/a");
pondering=1;
(void) Iterate(ChangeSide(wtm),think);
pondering=0;
if (!abort_search) ponder_completed=1;
if (ChangeSide(wtm))
rephead_w--;
else
rephead_b--;
last_opponent_move=0;
UnMakeMove(0,ponder_move,wtm);
/*
----------------------------------------------------------
| |
| search completed. there are two possible reasons for |
| us to get here. (1) the opponent made the predicted |
| move and we have used enough time on the search, or; |
| the operator typed in a command (or not-predicted |
| move) that requires the search to abort and restart. |
| |
----------------------------------------------------------
*/
if (made_predicted_move) return(1);
return(0);
}
/*
*******************************************************************************
* *
* Ponder() is the driver for "pondering" (thinking on the opponent's time.) *
* its operation is simple: Find a predicted move by (a) taking the second *
* move from the principal variation, or (b) call lookup to see if it finds *
* a suggested move from the transposition table. Then, make this move and *
* do a search from the resulting position. While pondering, one of three *
* things can happen: (1) A move is entered, and it matches the predicted *
* move. We then switch from pondering to thinking and search as normal; *
* (2) A move is entered, but it does not match the predicted move. We then *
* abort the search, unmake the pondered move, and then restart with the *
* move entered. (3) A command is entered. If it is a simple command, it *
* can be done without aborting the search or losing time. If not, we abort *
* the search, execute the command, and then attempt to restart pondering if *
* the command didn't make that impossible. *
* *
*******************************************************************************
*/
int Ponder(int wtm) {
TREE *const tree = block[0];
int dalpha = -999999, dbeta = 999999, i;
unsigned *n_ponder_moves, *mv;
int save_move_number, tlom, value;
/*
************************************************************
* *
* First, let's check to see if pondering is allowed, or *
* if we should avoid pondering on this move since it is *
* the first move of a game, or if the game is over, or *
* "force" mode is active, or there is input in the queue *
* that needs to be read and processed. *
* *
************************************************************
*/
if (!ponder || force || over || CheckInput())
return 0;
save_move_number = move_number;
/*
************************************************************
* *
* Check the ponder move for legality. If it is not a *
* legal move, we have to take action to find something to *
* ponder. *
* *
************************************************************
*/
strcpy(ponder_text, "none");
if (ponder_move) {
if (!VerifyMove(tree, 1, wtm, ponder_move)) {
ponder_move = 0;
Print(4095, "ERROR. ponder_move is illegal (1).\n");
Print(4095, "ERROR. PV pathl=%d\n", last_pv.pathl);
Print(4095, "ERROR. move=%d %x\n", ponder_move, ponder_move);
}
}
/*
************************************************************
* *
* First attempt, do a hash probe. However, since a hash *
* collision is remotely possible, we still need to verify *
* that the transposition/refutation best move is actually *
* legal. *
* *
************************************************************
*/
if (!ponder_move) {
HashProbe(tree, 0, 0, wtm, dalpha, dbeta, &value);
if (tree->hash_move[0])
ponder_move = tree->hash_move[0];
if (ponder_move) {
if (!VerifyMove(tree, 1, wtm, ponder_move)) {
Print(4095, "ERROR. ponder_move is illegal (2).\n");
Print(4095, "ERROR. move=%d %x\n", ponder_move, ponder_move);
ponder_move = 0;
}
}
}
/*
************************************************************
* *
* Second attempt. If that didn't work, then we try what *
* I call a "puzzling" search. Which is simply a shorter *
* time-limit search for the other side, to find something *
* to ponder. *
* *
************************************************************
*/
if (!ponder_move) {
TimeSet(puzzle);
if (time_limit < 20)
return 0;
puzzling = 1;
tree->status[1] = tree->status[0];
Print(32, " puzzling over a move to ponder.\n");
last_pv.pathl = 0;
last_pv.pathd = 0;
for (i = 0; i < MAXPLY; i++) {
tree->killers[i].move1 = 0;
tree->killers[i].move2 = 0;
}
Iterate(wtm, puzzle, 0);
for (i = 0; i < MAXPLY; i++) {
tree->killers[i].move1 = 0;
tree->killers[i].move2 = 0;
}
puzzling = 0;
if (tree->pv[0].pathl)
ponder_move = tree->pv[0].path[1];
if (!ponder_move)
return 0;
for (i = 1; i < (int) tree->pv[0].pathl; i++)
last_pv.path[i] = tree->pv[0].path[i + 1];
last_pv.pathl = tree->pv[0].pathl - 1;
last_pv.pathd = 0;
if (!VerifyMove(tree, 1, wtm, ponder_move)) {
ponder_move = 0;
Print(4095, "ERROR. ponder_move is illegal (3).\n");
Print(4095, "ERROR. PV pathl=%d\n", last_pv.pathl);
return 0;
}
}
/*
************************************************************
* *
* Display the move we are going to "ponder". *
* *
************************************************************
*/
if (wtm)
Print(32, "White(%d): %s [pondering]\n", move_number, OutputMove(tree, 0,
wtm, ponder_move));
else
Print(32, "Black(%d): %s [pondering]\n", move_number, OutputMove(tree, 0,
wtm, ponder_move));
sprintf(ponder_text, "%s", OutputMove(tree, 0, wtm, ponder_move));
if (post)
printf("Hint: %s\n", ponder_text);
/*
************************************************************
* *
* Set the ponder move list and eliminate illegal moves. *
* This list is used to test the move entered while we are *
* pondering, since we need a move list for the input *
* screening process. *
* *
************************************************************
*/
n_ponder_moves = GenerateCaptures(tree, 0, wtm, ponder_moves);
num_ponder_moves =
GenerateNoncaptures(tree, 0, wtm, n_ponder_moves) - ponder_moves;
for (mv = ponder_moves; mv < ponder_moves + num_ponder_moves; mv++) {
MakeMove(tree, 0, wtm, *mv);
if (Check(wtm)) {
UnmakeMove(tree, 0, wtm, *mv);
*mv = 0;
} else
UnmakeMove(tree, 0, wtm, *mv);
}
/*
************************************************************
* *
* Now, perform an iterated search, but with the special *
* "pondering" flag set which changes the time controls *
* since there is no need to stop searching until the *
* opponent makes a move. *
* *
************************************************************
*/
MakeMove(tree, 0, wtm, ponder_move);
tree->curmv[0] = ponder_move;
tree->rep_list[++rep_index] = HashKey;
tlom = last_opponent_move;
last_opponent_move = ponder_move;
if (kibitz)
strcpy(kibitz_text, "n/a");
thinking = 0;
pondering = 1;
if (!wtm)
move_number++;
ponder_value = Iterate(Flip(wtm), think, 0);
rep_index--;
move_number = save_move_number;
pondering = 0;
thinking = 0;
last_opponent_move = tlom;
UnmakeMove(tree, 0, wtm, ponder_move);
/*
************************************************************
* *
* Search completed. the possible return values are: *
* *
* (0) No pondering was done, period. *
* *
* (1) Pondering was done, opponent made the predicted *
* move, and we searched until time ran out in a *
* normal manner. *
* *
* (2) Pondering was done, but the ponder search *
* terminated due to either finding a mate, or the *
* maximum search depth was reached. The result of *
* this ponder search are valid, but only if the *
* opponent makes the correct (predicted) move. *
* *
* (3) Pondering was done, but the opponent either made a *
* different move, or entered a command that has to *
* interrupt the pondering search before the command *
* (or move) can be processed. This forces Main() to *
* avoid reading in a move/command since one has been *
* read into the command buffer already. *
* *
************************************************************
*/
if (input_status == 1)
return 1;
if (input_status == 2)
return 3;
return 2;
}
int NextMove(MOVES *m, int *flag) {
int move;
switch (m->phase) {
case 0: // return transposition table move, if legal
move = m->trans_move;
if (move
&& Legal(m->p, move)) {
m->phase = 1;
*flag = MV_HASH;
return move;
}
case 1: // helper phase: generate captures
m->last = GenerateCaptures(m->p, m->move);
ScoreCaptures(m);
m->next = m->move;
m->badp = m->bad;
m->phase = 2;
case 2: // return good captures, save bad ones on the separate list
while (m->next < m->last) {
move = SelectBest(m);
if (move == m->trans_move)
continue;
if (BadCapture(m->p, move)) {
*m->badp++ = move;
continue;
}
*flag = MV_CAPTURE;
return move;
}
case 3: // first killer move
move = m->killer1;
if (move
&& move != m->trans_move
&& m->p->pc[Tsq(move)] == NO_PC
&& Legal(m->p, move)) {
m->phase = 4;
*flag = MV_KILLER;
return move;
}
case 4: // second killer move
move = m->killer2;
if (move
&& move != m->trans_move
&& m->p->pc[Tsq(move)] == NO_PC
&& Legal(m->p, move)) {
m->phase = 5;
*flag = MV_KILLER;
return move;
}
case 5: // refutation move
move = m->ref_move;
if (move && move != m->trans_move
&& m->p->pc[Tsq(move)] == NO_PC
&& move != m->killer1
&& move != m->killer2
&& Legal(m->p, move)) {
m->phase = 6;
*flag = MV_NORMAL;
return move;
}
case 6: // helper phase: generate quiet moves
m->last = GenerateQuiet(m->p, m->move);
ScoreQuiet(m);
m->next = m->move;
m->phase = 7;
case 7: // return quiet moves
while (m->next < m->last) {
move = SelectBest(m);
if (move == m->trans_move
|| move == m->killer1
|| move == m->killer2
|| move == m->ref_move)
continue;
*flag = MV_NORMAL;
return move;
}
m->next = m->bad;
m->phase = 8;
case 8: // return bad captures
if (m->next < m->badp) {
*flag = MV_BADCAPT;
return *m->next++;
}
}
return 0;
}
/*
********************************************************************************
* *
* Quiesce() is the recursive routine used to implement the alpha/beta *
* negamax search (similar to minimax but simpler to code.) Quiesce() is *
* called whenever there is no "depth" remaining so that only capture moves *
* are searched deeper. *
* *
********************************************************************************
*/
int Quiesce(int alpha, int beta, int wtm, int ply)
{
register int initial_alpha, value, delta;
register int *next_move;
register int *goodmv, *movep, moves=0, *sortv, temp;
/*
----------------------------------------------------------
| |
| initialize. |
| |
----------------------------------------------------------
*/
if (ply >= MAXPLY-2) return(beta);
nodes_searched++;
next_time_check--;
last[ply]=last[ply-1];
initial_alpha=alpha;
/*
----------------------------------------------------------
| |
| now call Evaluate() to produce the "stand-pat" score |
| that will be returned if no capture is acceptable. |
| if this score is > alpha, then we also have to save |
| the "path" to this node as it is the PV that leads |
| to this score. |
| |
----------------------------------------------------------
*/
value=Evaluate(ply,wtm,alpha,beta);
if (value > alpha) {
if (value >= beta) return(value);
alpha=value;
pv[ply].path_length=ply-1;
pv[ply].path_hashed=0;
pv[ply].path_iteration_depth=iteration_depth;
}
/*
----------------------------------------------------------
| |
| generate captures and sort them based on (a) the value |
| of the captured piece - the value of the capturing |
| piece if this is > 0; or, (b) the value returned by |
| Swap(). if the value of the captured piece won't |
| bring the material score back up to near alpha, that |
| capture is discarded as "futile." |
| |
----------------------------------------------------------
*/
last[ply]=GenerateCaptures(ply, wtm, last[ply-1]);
delta=alpha-500-(wtm?Material:-Material);
goodmv=last[ply-1];
sortv=sort_value;
for (movep=last[ply-1];movep<last[ply];movep++)
if (p_values[Captured(*movep)+7]+p_values[Promote(*movep)+7] >= delta) {
if (Captured(*movep) == king) return(beta);
if (p_values[Piece(*movep)+7] < p_values[Captured(*movep)+7] ||
(p_values[Piece(*movep)+7] <= p_values[Captured(*movep)+7] &&
delta<=0)) {
*goodmv++=*movep;
*sortv++=p_values[Captured(*movep)+7];
moves++;
}
else {
temp=Swap(From(*movep),To(*movep),wtm);
if (temp >= 0) {
*sortv++=temp;
*goodmv++=*movep;
moves++;
}
}
}
/*
----------------------------------------------------------
| |
| don't disdain the lowly bubble sort here. the list of |
| captures is always short, and experiments with other |
| algorithms are always slightly slower. |
| |
----------------------------------------------------------
*/
if (moves > 1) {
register int done;
register int *end=last[ply-1]+moves-1;
do {
done=1;
sortv=sort_value;
movep=last[ply-1];
for (;movep<end;movep++,sortv++)
if (*sortv < *(sortv+1)) {
temp=*sortv;
*sortv=*(sortv+1);
*(sortv+1)=temp;
temp=*movep;
*movep=*(movep+1);
*(movep+1)=temp;
done=0;
}
} while(!done);
}
next_move=last[ply-1];
/*
----------------------------------------------------------
| |
| now iterate through the move list and search the |
| resulting positions. |
| |
----------------------------------------------------------
*/
while (moves--) {
current_move[ply]=*(next_move++);
#if !defined(FAST)
if (ply <= trace_level)
SearchTrace(ply,0,wtm,alpha,beta,"quiesce",CAPTURE_MOVES);
#endif
MakeMove(ply,current_move[ply],wtm);
value=-Quiesce(-beta,-alpha,ChangeSide(wtm),ply+1);
UnMakeMove(ply,current_move[ply],wtm);
if (value > alpha) {
if(value >= beta) return(value);
alpha=value;
}
}
/*
----------------------------------------------------------
| |
| all moves have been searched. return the search |
| result that was found. if the result is not the |
| original alpha score, then we need to return the PV |
| that is associated with this score. |
| |
----------------------------------------------------------
*/
if (alpha != initial_alpha) {
memcpy(&pv[ply-1].path[ply],&pv[ply].path[ply],
(pv[ply].path_length-ply+1)*sizeof(int));
memcpy(&pv[ply-1].path_hashed,&pv[ply].path_hashed,3);
pv[ply-1].path[ply-1]=current_move[ply-1];
}
return(alpha);
}