diff options
| -rw-r--r-- | chess-polyglot.el | 51 |
1 files changed, 22 insertions, 29 deletions
diff --git a/chess-polyglot.el b/chess-polyglot.el index b2ed430..a58ae8d 100644 --- a/chess-polyglot.el +++ b/chess-polyglot.el @@ -111,33 +111,28 @@ WEIGHT (an integer) is the relative weight of the move." On reaching end or beginning of buffer, stop and signal error." (forward-char (* n chess-polyglot-record-size))) -(defun chess-polyglot-read-moves (key low high) - "Read all moves associated with KEY from the current buffer. -LOW and HIGH are the number of the first and last record to consider in -the search." +(defsubst chess-polyglot-key-<= (lhs rhs) + "Non-nil if the polyglot key LHS is less than or equal to RHS." + (or (< (car lhs) (car rhs)) + (and (= (car lhs) (car rhs)) (<= (cdr lhs) (cdr rhs))))) + +(defun chess-polyglot-read-moves (key) + "Read all moves associated with KEY from the current buffer." (cl-assert (= (% (buffer-size) chess-polyglot-record-size) 0)) - (let* ((mid (/ (+ low high) 2)) - (mid-key (progn (chess-polyglot-goto-record mid) - (chess-polyglot-read-key)))) - (cond - ((= low high) (when (equal key mid-key) (chess-polyglot-read-move))) - ((< (car key) (car mid-key)) (chess-polyglot-read-moves key low mid)) - ((> (car key) (car mid-key)) (chess-polyglot-read-moves key (1+ mid) high)) - (t (cond - ((< (cdr key) (cdr mid-key)) (chess-polyglot-read-moves key low mid)) - ((> (cdr key) (cdr mid-key)) (chess-polyglot-read-moves key (1+ mid) high)) - (t (when (> (point) chess-polyglot-record-size) - (chess-polyglot-forward-record -1)) - (while (progn (forward-char -8) - (and (> (point) chess-polyglot-record-size) - (equal key (chess-polyglot-read-key)))) - (chess-polyglot-forward-record -1)) - (forward-char 8) ; skip over move and learn values - (let (moves) - (while (equal key (chess-polyglot-read-key)) - (setq moves (nconc moves (list (chess-polyglot-read-move)))) - (chess-polyglot-skip-learn)) - moves))))))) + (let ((left 0) (right (1- (/ (buffer-size) chess-polyglot-record-size)))) + (while (< left right) + (let ((middle (/ (+ left right) 2))) + (if (chess-polyglot-key-<= key (progn (chess-polyglot-goto-record middle) + (chess-polyglot-read-key))) + (setq right middle) + (setq left (1+ middle))))) + (cl-assert (= left right)) + (chess-polyglot-goto-record left) + (let ((moves ())) + (while (equal key (chess-polyglot-read-key)) + (setq moves (nconc moves (list (chess-polyglot-read-move)))) + (chess-polyglot-skip-learn)) + moves))) (defconst chess-polyglot-zorbist-keys [(2637767806 . 863464769) (720845184 . 95069639) (1155203408 . 610415943) @@ -461,9 +456,7 @@ Use `chess-ply-keyword' on elements of the returned list to retrieve them." (let (plies) (dolist (move (with-current-buffer book - (chess-polyglot-read-moves (chess-polyglot-pos-to-key position) - 0 (1- (/ (buffer-size) - chess-polyglot-record-size)))) + (chess-polyglot-read-moves (chess-polyglot-pos-to-key position))) plies) (let ((ply (apply #'chess-polyglot-move-to-ply position move))) (when ply |