4 ; Copyright © 2016 Keith Packard <keithp@keithp.com>
6 ; This program is free software; you can redistribute it and/or modify
7 ; it under the terms of the GNU General Public License as published by
8 ; the Free Software Foundation, either version 2 of the License, or
9 ; (at your option) any later version.
11 ; This program is distributed in the hope that it will be useful, but
12 ; WITHOUT ANY WARRANTY; without even the implied warranty of
13 ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 ; General Public License for more details.
18 ; ANSI control sequences
20 (defun move-to (col row)
21 (patom "\033[" row ";" col "H" nil)
28 (defun display-string (x y str)
33 ; Here's the pieces to display
35 (setq stack '(" * " " *** " " ***** " " ******* " " ********* " "***********"))
38 ; Here's all of the stacks of pieces
39 ; This is generated when the program is run
43 ; Display one stack, clearing any
46 (defun display-stack (x y clear stack)
49 (display-string x y (car stack))
50 (display-stack x (1+ y) 0 (cdr stack))
56 (display-string x y " ")
57 (display-stack x (1+ y) (1- clear) stack)
63 ; Position of the top of the stack on the screen
64 ; Shorter stacks start further down the screen
66 (defun stack-pos (y stack)
70 ; Display all of the stacks, spaced 20 columns apart
72 (defun display-stacks (x y stacks)
74 (display-stack x 0 (stack-pos y (car stacks)) (car stacks))
75 (display-stacks (+ x 20) y (cdr stacks)))
80 ; Display all of the stacks, then move the cursor
81 ; out of the way and flush the output
84 (display-stacks 0 top stacks)
89 ; Reset stacks to the starting state, with
90 ; all of the pieces in the first stack and the
93 (defun reset-stacks ()
94 (setq stacks (list stack nil nil))
95 (setq top (+ (length stack) 3))
99 ; more functions which could usefully
100 ; be in the rom image
108 ; Replace a stack in the list of stacks
111 (defun replace (list pos member)
112 (cond ((= pos 0) (cons member (cdr list)))
113 ((cons (car list) (replace (cdr list) (1- pos) member)))
117 ; Move a piece from the top of one stack
118 ; to the top of another
120 (defun move-piece (from to)
121 (let ((from-stack (nth stacks from))
122 (to-stack (nth stacks to))
123 (piece (car from-stack)))
124 (setq from-stack (cdr from-stack))
125 (setq to-stack (cons piece to-stack))
126 (setq stacks (replace stacks from from-stack))
127 (setq stacks (replace stacks to to-stack))
133 ; The implementation of the game
135 (defun _hanoi (n from to use)
143 (_hanoi (1- n) from use to)
144 (_hanoi 1 from to use)
145 (_hanoi (1- n) use to from)
151 ; A pretty interface which
152 ; resets the state of the game,
153 ; clears the screen and runs
157 (setq len (reset-stacks))