TD(lambda), and a big rework

NOTE: 6x6 weights are as-yet untrained

On the performance side:
* switch from linked-list chaining hash table to direct mapping
* cache check_win by hash
* persist transposition tables across plies (this was a big deal and difficult to puzzle out)
* add align directives to the network floats
* prepare_nn_input gained a small LUT to avoid branching (i suppose you might call this 1D embedding)
* apply mtune=native for the native builds

On the correctness side:
* Zobrist has now includes the ply parity
* the network now predicts something in [-1, 1] using tanh (approximated by polynomials)
* the training object is now MSE because we're learning a value estimate
* use .clangd instead of compile_commands.json

On the training side:
* completely forgo human-derived data set
* implement td(lambda), self-play, tournaments

1 files changed, 17 insertions, 5 deletions

diff --git a/include/actions.h b/include/actions.h
index 0127119..913a8cb 100644
--- a/include/actions.h
+++ b/include/actions.h
@@ -1,5 +1,5 @@
 /*
-  This file is part of ct.
+  This file is part of ctak.
 
   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
@@ -12,7 +12,7 @@
   General Public License for more details.
 
   You should have received a copy of the GNU General Public License
-  along with ct. If not, see <https://www.gnu.org/licenses/>.
+  along with ctak. If not, see <https://www.gnu.org/licenses/>.
 */
 
 #ifndef ACTIONS_H
@@ -55,13 +55,25 @@ extern int8_t move_deltas[4];
 // ===================================================================
 
 void actions_init(const uint8_t board_size);
-void actions_free(action_t *actions);
+
+/*
+ * Generate the legal actions. The move list is drawn from a static
+ * per-search-level scratch buffer: one buffer per recursion level,
+ * so nested generate calls at different levels do not clobber each
+ * other. `level' is the recursion depth within the current search
+ * (0 at the root). The returned pointer is valid until the next
+ * generate call at the same level.
+ */
+action_t *actions_generate_at(tak_state_p state, uint32_t *num_actions,
+                              const uint32_t level);
 
 action_t *actions_generate(tak_state_p state, uint32_t *num_actions);
 char action_in_list(action_t action, action_t *actions,
                     const uint32_t num_actions);
-void action_move_to_front(action_t action, action_t *actions,
-                          const uint32_t num_actions);
+// Move `action' to the front of the list. Returns EXIT_FAILURE (and
+// leaves the list untouched) if the action is not in the list.
+int action_move_to_front(action_t action, action_t *actions,
+                         const uint32_t num_actions);
 
 void action_take(tak_state_p state, const action_t action);
 void action_undo(tak_state_p state, const action_t action);