create (unused) thread.[ch] files.

I am still unsure if I will go for thread or process...

Makefile

@@ -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 hist.o
+	eval.o eval-defs.o eval-simple.o
 BB_OBJS       := $(FEN_OBJS)
 MOVEGEN_OBJS  := $(BB_OBJS) move-gen.o
 ATTACK_OBJS   := $(MOVEGEN_OBJS)

src/brchess.c

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

src/chessdefs.h

@@ -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.

src/eval-defs.h

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

src/eval.c

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

src/eval.h

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

src/fen.c

@@ -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.ply50 = 0;
+    tmppos.clock_50 = 0;
     tmppos.plycount = 1;
     if (sscanf(cur, "%hd%n", &tmp, &consumed) != 1)
         goto end;                                 /* early end, ignore w/o err */
 
-    tmppos.ply50 = tmp;
+    tmppos.clock_50 = 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->ply50,
+    sprintf(fen+cur, "%d %d", pos->clock_50,
             1 + (pos->plycount - (pos->turn == BLACK)) / 2);
     return fen;
 }

src/hist.c

@@ -37,16 +37,6 @@ 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
@@ -144,10 +134,9 @@ void hist_static_print(void)
 
     printf("UCI state history: ");
     while (true) {
-        printf("%s(#%lx r=%d) ",
+        printf("%s(#%lx) ",
                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);
@@ -165,10 +154,9 @@ void hist_print(pos_t *pos)
     state_t *st = &pos->state;
     printf("position states history: ");
     while (true) {
-        printf("%s(#%lx r=%d) ",
+        printf("%s(#%lx) ",
                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);

src/hist.h

@@ -48,7 +48,6 @@ 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);

src/move-do.c

@@ -24,7 +24,6 @@
 #include "position.h"
 #include "move-do.h"
 #include "hash.h"
-#include "hist.h"
 
 /**
  * move_do() - do move.
@@ -60,16 +59,14 @@ 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->ply50;
+    ++pos->clock_50;
     ++pos->plycount;
-    ++pos->plyroot;
     pos->en_passant = SQUARE_NONE;
     pos->turn = them;
     pos->captured = captured;
@@ -83,7 +80,7 @@ pos_t *move_do(pos_t *pos, const move_t move, state_t *state)
     }
 
     if (captured != EMPTY) {
-        pos->ply50 = 0;
+        pos->clock_50 = 0;
         bug_on(pos->board[to] == EMPTY || COLOR(pos->captured) != them);
         key ^= zobrist_pieces[captured][to];
         pos_clr_sq(pos, to);                      /* clear square */
@@ -102,7 +99,7 @@ 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->ply50 = 0;
+        pos->clock_50 = 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]) {
@@ -154,7 +151,6 @@ 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;
@@ -213,8 +209,6 @@ 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;
 }
 
@@ -233,16 +227,14 @@ 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->ply50;
+    ++pos->clock_50;
     ++pos->plycount;
-    ++pos->plyroot;
     pos->en_passant = SQUARE_NONE;
     pos->turn = them;
     pos->captured = captured;
@@ -256,7 +248,8 @@ pos_t *move_do_alt(pos_t *pos, const move_t move, state_t *state)
     }
 
     if (captured != EMPTY) {
-        pos->ply50 = 0;
+        pos->clock_50 = 0;
+        //pos->captured = pos->board[to];           /* save capture info */
         bug_on(pos->board[to] == EMPTY || COLOR(pos->captured) != them);
         key ^= zobrist_pieces[captured][to];
         pos_clr_sq(pos, to);                      /* clear square */
@@ -275,7 +268,7 @@ 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->ply50 = 0;
+        pos->clock_50 = 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]) {
@@ -327,7 +320,6 @@ 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;
@@ -369,7 +361,5 @@ 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;
 }

src/perft.c

@@ -40,65 +40,7 @@
  *
  * @return: total moves found at @depth level.
  */
-static u64 do_perft(pos_t *pos, int depth)
+u64 perft(pos_t *pos, int depth, int ply, bool divide)
-{
-    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;
@@ -114,15 +56,30 @@ u64 perft(pos_t *pos, int depth, bool divide)
             subnodes = 1;
         } else {
             move_do(pos, *move, &state);
-            subnodes = do_perft(pos, depth - 1);
+            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);
+            }
             move_undo(pos, *move, &state);
         }
-        if (divide) {
+        nodes += subnodes;
+        if (ply == 1 && divide) {
             char movestr[8];
             printf("%s: %lu\n", move_to_str(movestr, *move, 0), subnodes);
         }
-        nodes += subnodes;
     }
+
     return nodes;
 }
 

src/perft.h

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

src/position.c

@@ -108,7 +108,6 @@ pos_t *pos_clear(pos_t *pos)
 
     pos->king[WHITE] = SQUARE_NONE;
     pos->king[BLACK] = SQUARE_NONE;
-    pos->prev = HIST_START;
 
     return pos;
 }
@@ -131,7 +130,7 @@ 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(ply50) || _cmpf(plycount) || _cmpf(captured))
+        _cmpf(clock_50) || _cmpf(plycount) || _cmpf(captured))
         goto end;
 
     if (_cmpf(checkers) || _cmpf(pinners) || _cmpf(blockers))
@@ -181,36 +180,6 @@ 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

src/position.h

@@ -27,7 +27,6 @@
 #include "piece.h"
 #include "move.h"
 #include "board.h"
-#include "eval-defs.h"
 
 typedef struct __pos_s {
     u64 node_count;                               /* evaluated nodes */
@@ -51,14 +50,14 @@ 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 */
-                        phase_t phase;
+                        u8 clock_50;
-                        u8 ply50;
-                        u8 repcount;              /* repetition count */
         );
     eval_t eval;
     bitboard_t checkers;                          /* opponent checkers */
@@ -67,8 +66,6 @@ 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;
@@ -186,7 +183,6 @@ 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);

src/search.c

@@ -20,21 +20,6 @@
 #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.

src/search.h

@@ -16,7 +16,6 @@
 
 #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);
 

src/thread.c

@@ -0,0 +1,69 @@
+/* thread.c - thread management.
+ *
+ * Copyright (C) 2024 Bruno Raoult ("br")
+ * Licensed under the GNU General Public License v3.0 or later.
+ * Some rights reserved. See COPYING.
+ *
+ * You should have received a copy of the GNU General Public License along with this
+ * program. If not, see <https://www.gnu.org/licenses/gpl-3.0-standalone.html>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later <https://spdx.org/licenses/GPL-3.0-or-later.html>
+ *
+ */
+
+#include <stdio.h>
+
+#include <brlib.h>
+#include <pthread.h>
+#include <poll.h>
+#include <sys/socket.h>
+
+#include "thread.h"
+
+/* Still have to decide: thread or process ?
+ *
+ */
+thread_pool_t threadpool;
+
+/**
+ * thrd_create - initialize thrd.
+ */
+int thrd_create(__unused int num)
+{
+    int fd[2];
+    /* shall we make a communication channel via a pipe or socket ? */
+    int __unused ret = socketpair(AF_LOCAL, SOCK_SEQPACKET, PF_LOCAL, fd);
+    return 1;
+}
+
+/**
+ * thread_init - initialize thread pool.
+ */
+int thread_init(int nb)
+{
+    nb = clamp(nb, MIN_THRDS, MAX_THRDS);
+
+    /* stop unwanted threads, always keep 1 */
+    for (int i = nb + 1; i < threadpool.nb; ++i) {
+        printf("stopping thread %d - status = \n", i);
+        threadpool.thread[i].cmd = THRD_DO_QUIT;
+    }
+    for (int i = threadpool.nb; i < nb; ++i) {
+        printf("creating thread %d - status = \n", i);
+        thrd_create(i);
+
+    }
+
+    return nb;
+}
+
+/*
+  communication:
+  main thread -> thread
+           commands via memory
+  thread -> main thread
+           status via memory
+           output via pipe/socket
+  thread output will be output/filtered by main thread
+
+ */

src/thread.h

@@ -0,0 +1,55 @@
+/* thread.h - thread management.
+ *
+ * Copyright (C) 2021-2024 Bruno Raoult ("br")
+ * Licensed under the GNU General Public License v3.0 or later.
+ * Some rights reserved. See COPYING.
+ *
+ * You should have received a copy of the GNU General Public License along with this
+ * program. If not, see <https://www.gnu.org/licenses/gpl-3.0-standalone.html>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later <https://spdx.org/licenses/GPL-3.0-or-later.html>
+ *
+ */
+
+#ifndef THREAD_H
+#define THREAD_H
+
+#include <pthread.h>
+
+#include <brlib.h>
+
+#include "position.h"
+
+#define MIN_THRDS 1
+#define MAX_THRDS 16
+
+typedef enum {
+    THRD_DEAD,
+    THRD_IDLE,
+    THRD_WORKING,
+} thread_status_t;
+
+typedef enum {
+    /* main thread to subs */
+    THRD_DO_SEARCH,
+    THRD_DO_STOP,
+    THRD_DO_QUIT,
+} thread_cmd_t;
+
+typedef struct {
+    int id;
+    thread_status_t status;
+    thread_cmd_t cmd;
+    int fd[2];
+    pos_t pos;
+} thread_t;
+
+typedef struct {
+    int nb;
+    thread_t thread[MAX_THRDS + 1];
+} thread_pool_t;
+
+int thrd_create(__unused int num);
+int thread_init(int nb);
+
+#endif  /* THREAD_H */

src/uci.c

@@ -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) {
@@ -395,26 +395,13 @@ 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 */
+        hist_push(&pos->state);                   /* push previous state */
-        move_do(pos, move, hist_next());
+        move_do(pos, move, &state);
-        printf("repet=%d\n", pos->repcount);
+        pos_print(pos);
-        //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);
     }
-    /* reset position root, and decrease history moves repcounts.
+    //hist_static_print();
-     * 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;
 }
 
@@ -442,7 +429,7 @@ 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, divide);
+            perft(pos, depth, 1, divide);
         else
             perft_alt(pos, depth, 1, divide);
     }
@@ -451,7 +438,7 @@ int do_perft(__unused pos_t *pos, __unused char *arg)
 
 int do_hist(__unused pos_t *pos, __unused char *arg)
 {
-    hist_print(pos);
+    hist_static_print();
     return 0;
 }
 

test/perft-test.c

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