UCI moves && games states list

src/hist.c

@@ -0,0 +1,123 @@
+/* hist.c - history 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 <brlib.h>
+#include <bug.h>
+
+#include "position.h"
+#include "hash.h"
+#include "move.h"
+#include "hist.h"
+
+hist_t hist = {
+    .nstates = 1,
+    { { .move = MOVE_NO_MOVE, .key = U64(0), .prev = &hist.state[0] } },
+};
+
+/**
+ * hist_init() - initialize history states data.
+ *
+ * This should be done every time a new position must be handled.
+ */
+void hist_init(void)
+{
+    hist.nstates       = 1;
+    hist.state[0].key  = U64(0);
+    hist.state[0].move = MOVE_NO_MOVE;
+    hist.state[0].prev = &hist.state[0];
+}
+
+/**
+ * hist_push() - add a state and move to hist
+ * @st:   &state_t to add
+ * @move: &move_t to add in @st
+ */
+void hist_push(state_t *st, move_t *move)
+{
+    int last = hist.nstates++;
+
+    bug_on(last >= HIST_SIZE);
+    hist.state[last] = *st;
+    hist.state[last].prev = &hist.state[last - 1];
+    hist.state[last].move = *move;
+}
+
+/**
+ * hist_pop() - return last state from hist entry, and remove it from list
+ *
+ * Not used, only for debug.
+ */
+state_t *hist_pop(void)
+{
+    return hist.state + --hist.nstates;
+}
+
+/**
+ * hist_last() - return last state from hist.
+ */
+state_t *hist_last(void)
+{
+    return hist.state + hist.nstates - 1;
+}
+
+/**
+ * hist_prev() - return a state's ancestor.
+ * @st: &state_t state
+ *
+ * No test is done on ancestor. Caller should check it is different
+ * from HIST_START.
+ */
+state_t *hist_prev(state_t *st)
+{
+    return st->prev;
+}
+
+/**
+ * hist_prev2() - return a state's second ancestor.
+ * @st: &state_t state
+ *
+ * No test is done on ancestors. Caller should check it is different
+ * from HIST_START.
+ */
+state_t *hist_prev2(state_t *st)
+{
+    return st->prev->prev;
+}
+
+/**
+ * hist_prev4() - return a state's 4th ancestor.
+ * @st: &state_t state
+ *
+ * No test is done on ancestors. Caller should check it is different
+ * from HIST_START.
+ */
+state_t *hist_prev4(state_t *st)
+{
+    return st->prev->prev->prev->prev;
+}
+
+/**
+ * hist_print() - print hist entries
+ */
+void hist_static_print(void)
+{
+    char movestr[8];
+
+    printf("rev history: ");
+    for (state_t *p = hist_last(); p != HIST_START; p = hist_prev(p)) {
+        printf("%s(%lx) ",
+               p->move == MOVE_NO_MOVE? "none": move_to_str(movestr, p->move, 0),
+               hash_short(p->key));
+    }
+    printf("\n");
+}