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add repetition detection, root position count

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- hist.c: add hist_next() - get next entry in history
- state_t: remove plycount, clock_50 -> ply50, add phase, repcount
- pos_t: add plycount, plyroot
- state_t moved to chessdefs.h
- perft-test: split perft from do_perft (todo for perft_alt)
- position.c: add pos_repcount()
- search.c: add is_draw()
- uci: set root position (after moves), adjust history moves repcount
This commit is contained in:
Bruno Raoult
2024-08-04 09:37:58 +02:00
parent 01af1f5c49
commit 0ff41c408b
18 changed files with 183 additions and 55 deletions
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2
Makefile
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@@ -415,7 +415,7 @@ TEST += movedo-test perft-test tt-test
PIECE_OBJS := piece.o
FEN_OBJS := $(PIECE_OBJS) fen.o position.o bitboard.o board.o \
hq.o attack.o hash.o init.o util.o alloc.o move.o \
eval.o eval-defs.o eval-simple.o
eval.o eval-defs.o eval-simple.o hist.o
BB_OBJS := $(FEN_OBJS)
MOVEGEN_OBJS := $(BB_OBJS) move-gen.o
ATTACK_OBJS := $(MOVEGEN_OBJS)

4
src/brchess.c
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@@ -37,10 +37,10 @@ int main(int ac, char **av)
pos_t *pos;
int opt;
printf("brchess " VERSION "\n");
init_all();
pos = pos_new();
hist_link(pos);
printf("\nWelcome to brchess " VERSION "\nEngine ready.\n");
printf("Engine ready.\n");
// size_t len = 0;
// char *str = NULL;

2
src/chessdefs.h
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@@ -85,9 +85,9 @@ typedef struct __movelist_s movelist_t;
/* basic types
*/
typedef u64 bitboard_t;
typedef s16 eval_t;
typedef s8 phase_t;
/* forward enum definition is impossible in C11.
* To simplify cross-dependancies, all important enum are moved here.

2
src/eval-defs.h
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@@ -14,7 +14,6 @@
#ifndef EVAL_DEFS_H
#define EVAL_DEFS_H
#include "chessdefs.h"
#include "piece.h"
#include "eval.h"
@@ -26,7 +25,6 @@ enum {
ENDGAME,
PHASE_NB
};
typedef s16 phase_t;
/* pieces weight in phase calculation.
*/

2
src/eval.c
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@@ -30,7 +30,7 @@
*
* @return:
*/
s16 calc_phase(pos_t *pos)
phase_t calc_phase(pos_t *pos)
{
int phase = ALL_PHASE;
phase -= P_PHASE * popcount64(pos->bb[WHITE][PAWN] | pos->bb[BLACK][PAWN]);

2
src/eval.h
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@@ -19,7 +19,7 @@
#include "chessdefs.h"
#include "eval-defs.h"
s16 calc_phase(pos_t *pos);
phase_t calc_phase(pos_t *pos);
eval_t eval_mobility(pos_t *pos, bool color);
eval_t eval_square_control(pos_t *pos, bool color);

6
src/fen.c
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@@ -230,12 +230,12 @@ pos_t *fen2pos(pos_t *pos, const char *fen)
/* 5) half moves since last capture or pawn move (50 moves rule)
*/
tmppos.clock_50 = 0;
tmppos.ply50 = 0;
tmppos.plycount = 1;
if (sscanf(cur, "%hd%n", &tmp, &consumed) != 1)
goto end; /* early end, ignore w/o err */
tmppos.clock_50 = tmp;
tmppos.ply50 = tmp;
cur += consumed;
SKIP_BLANK(cur);
@@ -350,7 +350,7 @@ char *pos2fen(const pos_t *pos, char *fen)
/* 5) moves since last capture or pawn move (50 moves rule)
* 6) current full move number, starting with 1
*/
sprintf(fen+cur, "%d %d", pos->clock_50,
sprintf(fen+cur, "%d %d", pos->ply50,
1 + (pos->plycount - (pos->turn == BLACK)) / 2);
return fen;
}

20
src/hist.c
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@@ -37,6 +37,16 @@ void hist_init(void)
hist.state[0].prev = &hist.state[0];
}
/**
* hist_next() - get next history slot.
*
* return: @state_t next history slot.
*/
state_t *hist_next(void)
{
return hist.state + hist.nstates++;
}
/**
* hist_push() - add a state to hist list
* @st: &state_t to add
@@ -134,9 +144,10 @@ void hist_static_print(void)
printf("UCI state history: ");
while (true) {
printf("%s(#%lx) ",
printf("%s(#%lx r=%d) ",
move_to_str(movestr, st->move, 0),
hash_short(st->key));
hash_short(st->key),
st->repcount);
if (st == HIST_START)
break;
st = hist_prev(st);
@@ -154,9 +165,10 @@ void hist_print(pos_t *pos)
state_t *st = &pos->state;
printf("position states history: ");
while (true) {
printf("%s(#%lx) ",
printf("%s(#%lx r=%d) ",
move_to_str(movestr, st->move, 0),
hash_short(st->key));
hash_short(st->key),
st->repcount);
if (st == HIST_START)
break;
st = hist_prev(st);

1
src/hist.h
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@@ -48,6 +48,7 @@ extern hist_t hist;
#define HIST_START (hist.state)
void hist_init(void);
state_t *hist_next(void);
void hist_push(state_t *st); //, move_t *move);
void hist_link(pos_t *pos);
state_t *hist_pop(void);

24
src/move-do.c
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@@ -24,6 +24,7 @@
#include "position.h"
#include "move-do.h"
#include "hash.h"
#include "hist.h"
/**
* move_do() - do move.
@@ -59,14 +60,16 @@ pos_t *move_do(pos_t *pos, const move_t move, state_t *state)
hkey_t key = pos->key;
*state = pos->state; /* save irreversible changes */
pos->prev = state;
/* update key: switch turn, reset castling and ep */
key ^= zobrist_turn;
key ^= zobrist_castling[pos->castle];
key ^= zobrist_ep[EP_ZOBRIST_IDX(pos->en_passant)];
++pos->clock_50;
++pos->ply50;
++pos->plycount;
++pos->plyroot;
pos->en_passant = SQUARE_NONE;
pos->turn = them;
pos->captured = captured;
@@ -80,7 +83,7 @@ pos_t *move_do(pos_t *pos, const move_t move, state_t *state)
}
if (captured != EMPTY) {
pos->clock_50 = 0;
pos->ply50 = 0;
bug_on(pos->board[to] == EMPTY || COLOR(pos->captured) != them);
key ^= zobrist_pieces[captured][to];
pos_clr_sq(pos, to); /* clear square */
@@ -99,7 +102,7 @@ pos_t *move_do(pos_t *pos, const move_t move, state_t *state)
pos_clr_sq(pos, rookfrom);
pos->castle = clr_castle(pos->castle, us);
} else if (ptype == PAWN) { /* pawn non capture or e.p. */
pos->clock_50 = 0;
pos->ply50 = 0;
if (from + up + up == to) { /* if pawn double push, set e.p. */
square_t ep = from + up;
if (bb_pawn_attacks[us][ep] & pos->bb[them][PAWN]) {
@@ -151,6 +154,7 @@ pos_t *move_do(pos_t *pos, const move_t move, state_t *state)
pos->key = key;
pos->repcount = pos_repcount(pos);
zobrist_verify(pos);
return pos;
@@ -209,6 +213,8 @@ pos_t *move_undo(pos_t *pos, const move_t move, const state_t *state)
pos->state = *state; /* restore irreversible changes */
pos->turn = us;
--pos->plycount;
--pos->plyroot;
return pos;
}
@@ -227,14 +233,16 @@ pos_t *move_do_alt(pos_t *pos, const move_t move, state_t *state)
hkey_t key = pos->key;
*state = pos->state; /* save irreversible changes */
pos->prev = state;
/* update key: switch turn, reset castling and ep */
key ^= zobrist_turn;
key ^= zobrist_castling[pos->castle];
key ^= zobrist_ep[EP_ZOBRIST_IDX(pos->en_passant)];
++pos->clock_50;
++pos->ply50;
++pos->plycount;
++pos->plyroot;
pos->en_passant = SQUARE_NONE;
pos->turn = them;
pos->captured = captured;
@@ -248,8 +256,7 @@ pos_t *move_do_alt(pos_t *pos, const move_t move, state_t *state)
}
if (captured != EMPTY) {
pos->clock_50 = 0;
//pos->captured = pos->board[to]; /* save capture info */
pos->ply50 = 0;
bug_on(pos->board[to] == EMPTY || COLOR(pos->captured) != them);
key ^= zobrist_pieces[captured][to];
pos_clr_sq(pos, to); /* clear square */
@@ -268,7 +275,7 @@ pos_t *move_do_alt(pos_t *pos, const move_t move, state_t *state)
pos_clr_sq(pos, rookfrom);
pos->castle = clr_castle(pos->castle, us);
} else if (ptype == PAWN) { /* pawn non capture or e.p. */
pos->clock_50 = 0;
pos->ply50 = 0;
if (from + up + up == to) { /* if pawn double push, set e.p. */
square_t ep = from + up;
if (bb_pawn_attacks[us][ep] & pos->bb[them][PAWN]) {
@@ -320,6 +327,7 @@ pos_t *move_do_alt(pos_t *pos, const move_t move, state_t *state)
pos->key = key;
pos->repcount = pos_repcount(pos);
zobrist_verify(pos);
return pos;
@@ -361,5 +369,7 @@ pos_t *move_undo_alt(pos_t *pos, const move_t move, const state_t *state)
pos->state = *state; /* restore irreversible changes */
pos->turn = us;
--pos->plycount;
--pos->plyroot;
return pos;
}

81
src/perft.c
View File

@@ -40,7 +40,65 @@
*
* @return: total moves found at @depth level.
*/
u64 perft(pos_t *pos, int depth, int ply, bool divide)
static u64 do_perft(pos_t *pos, int depth)
{
u64 subnodes = 0, nodes = 0;
movelist_t movelist;
move_t *move, *last;
state_t state;
pos_set_checkers_pinners_blockers(pos);
pos_legal(pos, pos_gen_pseudo(pos, &movelist));
if (depth == 1)
return movelist.nmoves;
last = movelist.move + movelist.nmoves;
for (move = movelist.move; move < last; ++move) {
move_do(pos, *move, &state);
if (depth == 2) {
movelist_t movelist2;
pos_set_checkers_pinners_blockers(pos);
subnodes = pos_legal(pos, pos_gen_pseudo(pos, &movelist2))->nmoves;
} else if (pos->plyroot >= 3) {
hentry_t *entry = tt_probe_perft(pos->key, depth);
if (entry != TT_MISS) {
subnodes = HASH_PERFT_VAL(entry->data);
} else {
subnodes = do_perft(pos, depth - 1);
tt_store_perft(pos->key, depth, subnodes);
}
} else {
subnodes = do_perft(pos, depth - 1);
}
move_undo(pos, *move, &state);
nodes += subnodes;
}
return nodes;
}
/**
* perft() - Perform perft on position
* @pos: &position to search
* @depth: Wanted depth.
* @ply: current perft depth level (root = 1)
* @divide: output total for 1st level moves.
*
* Run perft on a position. This function displays the available moves at @depth
* level for each possible first move, and the total of moves.
*
* This version uses the algorithm:
* if last depth
* return 1;
* gen legal moves
* loop for legal move
* do-move
* perft (depth -1)
* undo-move
*
* @return: total moves found at @depth level.
*/
u64 perft(pos_t *pos, int depth, bool divide)
{
u64 subnodes = 0, nodes = 0;
movelist_t movelist;
@@ -56,30 +114,15 @@ u64 perft(pos_t *pos, int depth, int ply, bool divide)
subnodes = 1;
} else {
move_do(pos, *move, &state);
if (depth == 2) {
movelist_t movelist2;
pos_set_checkers_pinners_blockers(pos);
subnodes = pos_legal(pos, pos_gen_pseudo(pos, &movelist2))->nmoves;
} else if (ply >= 3) {
hentry_t *entry = tt_probe_perft(pos->key, depth);
if (entry != TT_MISS) {
subnodes = HASH_PERFT_VAL(entry->data);
} else {
subnodes = perft(pos, depth - 1, ply + 1, divide);
tt_store_perft(pos->key, depth, subnodes);
}
} else {
subnodes = perft(pos, depth - 1, ply + 1, divide);
}
subnodes = do_perft(pos, depth - 1);
move_undo(pos, *move, &state);
}
nodes += subnodes;
if (ply == 1 && divide) {
if (divide) {
char movestr[8];
printf("%s: %lu\n", move_to_str(movestr, *move, 0), subnodes);
}
nodes += subnodes;
}
return nodes;
}

2
src/perft.h
View File

@@ -16,7 +16,7 @@
#include "position.h"
u64 perft(pos_t *pos, int depth, int ply, bool output);
u64 perft(pos_t *pos, int depth,/* int ply,*/ bool divide);
u64 perft_alt(pos_t *pos, int depth, int ply, bool output);
#endif /* PERFT_H */

33
src/position.c
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@@ -108,6 +108,7 @@ pos_t *pos_clear(pos_t *pos)
pos->king[WHITE] = SQUARE_NONE;
pos->king[BLACK] = SQUARE_NONE;
pos->prev = HIST_START;
return pos;
}
@@ -130,7 +131,7 @@ bool pos_cmp(const pos_t *pos1, const pos_t *pos2)
/* move_do/undo position state */
if (_cmpf(key) || _cmpf(en_passant) || _cmpf(castle) ||
_cmpf(clock_50) || _cmpf(plycount) || _cmpf(captured))
_cmpf(ply50) || _cmpf(plycount) || _cmpf(captured))
goto end;
if (_cmpf(checkers) || _cmpf(pinners) || _cmpf(blockers))
@@ -180,6 +181,36 @@ bitboard_t pos_checkers(const pos_t *pos, const color_t color)
return sq_attackers(pos, occ, pos->king[color], OPPONENT(color));
}
/**
* pos_repcount() - return position repetition count.
* @pos: &position to search
*
* Attention: positions before (and including) root position repcount is
* decreased by one. See do_moves() in uci.c.
*
* @return: The number of repetitions in history, zero otherwise.
*/
u8 pos_repcount(pos_t *pos)
{
int c50 = pos->ply50;
state_t *st = &pos->state;
hkey_t key = pos->key;
st = hist_prev4(st);
//printf("is rep: START=%p ", HIST_START);
//printf("state=%p diff=%zd c50=%d k1=%#lx k2=%#lx\n",
// st, st - HIST_START, c50, hash_short(pos->key), hash_short(st->key));
/* attention, what about root position ? Isn't it dangerous to compare with
* its key ? like: st->prev != HIST_START
*/
for (; c50 >= 0 && st != HIST_START; st = hist_prev2(st), c50 -= 2) {
if (key == st->key)
return st->repcount + 1;
}
return false;
}
/**
* pos_set_checkers_pinners_blockers() - calculate checkers, pinners and blockers.
* @pos: &position

10
src/position.h
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@@ -27,6 +27,7 @@
#include "piece.h"
#include "move.h"
#include "board.h"
#include "eval-defs.h"
typedef struct __pos_s {
u64 node_count; /* evaluated nodes */
@@ -50,14 +51,14 @@ typedef struct __pos_s {
/* 16 bits */
move_t move;
u16 plycount; /* plies so far, start from 1 */
s16 phase;
/* 8 bits */
square_t en_passant;
castle_rights_t castle;
piece_t captured; /* only used in move_undo */
u8 clock_50;
phase_t phase;
u8 ply50;
u8 repcount; /* repetition count */
);
eval_t eval;
bitboard_t checkers; /* opponent checkers */
@@ -66,6 +67,8 @@ typedef struct __pos_s {
piece_t board[BOARDSIZE];
bitboard_t bb[2][PT_NB]; /* bb[0][PAWN], bb[1][ALL_PIECES] */
square_t king[2]; /* dup with bb, faster retrieval */
u16 plycount; /* plies in game, start from 1 */
u8 plyroot; /* plies since search root. root=0 */
} pos_t;
typedef struct state_s state_t;
@@ -183,6 +186,7 @@ void pos_del(pos_t *pos);
pos_t *pos_clear(pos_t *pos);
bool pos_cmp(const pos_t *pos1, const pos_t *pos2);
u8 pos_repcount(pos_t *pos);
void pos_set_checkers_pinners_blockers(pos_t *pos);
void pos_set_pinners_blockers(pos_t *pos);
bitboard_t pos_checkers(const pos_t *pos, const color_t color);

15
src/search.c
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@@ -20,6 +20,21 @@
#include "move-do.h"
#include "search.h"
#include "attack.h"
#include "hist.h"
/**
* is_draw() - check if position is draw by 50 or repetition rule.
* @pos: &position to search
*
* Note that states before (and including) root position state have
* their repcount decreased by one.
*
* @return: The @pos negamax evaluation.
*/
bool is_draw(pos_t *pos)
{
return (pos->ply50 > 100 || pos->repcount);
}
/**
* negamax() - search position negamax.

1
src/search.h
View File

@@ -16,6 +16,7 @@
#include "position.h"
bool is_draw(pos_t *pos);
//eval_t negamax(pos_t *pos, int depth, int color);
//eval_t pvs(pos_t *pos, int depth, int alpha, int beta, int color);

29
src/uci.c
View File

@@ -370,7 +370,7 @@ int do_position(pos_t *pos, char *arg)
}
/* link last position t history */
//hist_pop();
hist_link(pos);
//hist_link(pos);
return 1;
}
@@ -378,8 +378,8 @@ int do_moves(__unused pos_t *pos, char *arg)
{
char *saveptr = NULL, *token, check[8];
move_t move;
state_t state;
movelist_t movelist;
saveptr = NULL;
token = strtok_r(arg, " ", &saveptr);
while (token) {
@@ -395,13 +395,26 @@ int do_moves(__unused pos_t *pos, char *arg)
return 1;
}
//printf("move: %s\n", move_to_str(check, move, 0));
hist_push(&pos->state); /* push previous state */
move_do(pos, move, &state);
pos_print(pos);
//hist_push(&pos->state); /* push previous state */
move_do(pos, move, hist_next());
printf("repet=%d\n", pos->repcount);
//if (is_repetition(pos))
// printf("rep detected\n");
//else if(is_draw(pos))
// printf("draw detected\n");
hist_static_print();
token = strtok_r(NULL, " ", &saveptr);
}
//hist_static_print();
/* reset position root, and decrease history moves repcounts.
* TODO: Maybe use "ucinewgame" to decide when to perform this decrease ?
*/
pos->plyroot = 0;
for (state_t *st = &pos->state; st != HIST_START; st = hist_prev(st)) {
//printf("adjust rep=%d->\n");
st->repcount = max(0, st->repcount - 1);
}
pos_print(pos);
hist_print(pos);
return 1;
}
@@ -429,7 +442,7 @@ int do_perft(__unused pos_t *pos, __unused char *arg)
printf("perft: divide=%d alt=%d depth=%d\n", divide, alt, depth);
if (depth > 0) {
if (!alt)
perft(pos, depth, 1, divide);
perft(pos, depth, divide);
else
perft_alt(pos, depth, 1, divide);
}
@@ -438,7 +451,7 @@ int do_perft(__unused pos_t *pos, __unused char *arg)
int do_hist(__unused pos_t *pos, __unused char *arg)
{
hist_static_print();
hist_print(pos);
return 0;
}

2
test/perft-test.c
View File

@@ -364,7 +364,7 @@ int main(int ac, char**av)
if (run & 1) {
clock_start(&clock);
my_count = perft(pos, depth, 1, divide);
my_count = perft(pos, depth, divide);
ms = clock_elapsed_ms(&clock);
if (!ms) {
res[0].skipped++;