2 ;;; An implementation of the Memory Array Redcode Simulator (MARS)
13 (define core-size 8000)
14 (define max-steps 10000)
20 (define ((blah x y) . args)
25 (define ((make-instr opcode modifier A-mode A-num B-mode B-num name) . args)
27 (('copy n) (make-instr opcode modifier A-mode A-num B-mode B-num n))
29 (('modifier) modifier)
35 (('print) (print opcode
36 (if (null? modifier) "" (concat "." modifier))
37 " " (mode-string A-mode) A-num
38 ", " (mode-string B-mode) B-num
39 (if (null? name) "" (concat " ; " name))))
40 (('set-opcode! x n) (set! opcode x) (set! name n))
41 (('set-modifier! x n) (set! modifier x) (set! name n))
42 (('set-A-mode! x n) (set! A-mode x) (set! name n))
43 (('set-A-num! x n) (set! A-num x) (set! name n))
44 (('set-B-mode! x n) (set! B-mode x) (set! name n))
45 (('set-B-num! x n) (set! B-num x) (set! name n))))
47 (define (mode-string mode)
53 ((pre-indirect-A "{"))
54 ((pre-indirect-B "<"))
55 ((post-indirect-A "}"))
56 ((post-indirect-B ">"))))
58 (define initial-instruction
59 (make-instr 'DAT '() 'immediate 0 'immediate 0 '()))
61 ;;; Memory setup and addressing
64 (define core (make-vector core-size '()))
66 (define (initialize-core)
68 (unless (< i core-size)
69 (vector-set! core i (initial-instruction 'copy '()))
72 (define (addr+ . args)
74 (modulo (+ a b core-size) core-size))
80 (define (make-prog name instrs offset)
81 (list name instructions offset))
83 (define (prog-name prog) (list-ref prog 0))
84 (define (prog-instrs prog) (list-ref prog 1))
85 (define (prog-offset prog) (list-ref prog 2))
87 (define (install-prog prog addr)
89 (instrs (prog-instrs prog)))
90 (unless (null? instrs)
91 (vector-set! core ptr (instr-copy (car instrs)))
92 (loop (addr+ ptr 1) (cdr instrs))))
93 (make-player (prog-name prog)
94 (addr+ addr (prog-offset prog))))
96 (define (can-install-prog? prog-len addr)
101 (if ((vector-ref core ptr) 'name)
106 (define (install-progs progs)
107 (let loop ((players '())
109 (if (null? progs-left)
111 (let ((addr (pseudo-random-integer core-size))
112 (prog (car progs-left)))
113 (if (can-install-prog? (length (prog-instrs prog)) addr)
114 (loop (cons (install-prog prog addr) players)
116 (loop players progs-left))))))
118 (define (make-player name ptr)
121 (define (player-set-ptrs! player ptrs)
122 (set-cdr! prog-queue ptrs))
125 ;;; Executive function
128 (define (run players step)
130 ((> step max-steps) players) ;Tie between remaining players
131 ((<= (length players) 1) players) ;There's only one player left who thus wins
133 (let ((player (car players))
134 (other-players (cdr players))
135 (ptrs (player-ptrs player)))
136 (let ((new-ptrs (execute-instr (car ptrs))))
138 (run other-players (+ step 1))
140 (player-set-ptrs! (append (cdr ptrs) new-ptrs))
141 (run (append other-players (list player)) (+ step 1)))))))))
143 (define (execute-instr ptr)
144 (let* ((instr (vector-ref core ptr))
145 (A-pointer (eval-operand (instr-A-mode instr) (instr-A-num) ptr))
146 (B-pointer (eval-operand (instr-B-mode instr) (instr-B-num) ptr))
147 (modifier (instr-modifier instr)))
148 (case (instr-opcode instr)
149 ((DAT) '()) ;Game over, man, game over!
165 (error "Unrecognised opcode" (instr-opcode instr))))))
167 (define (eval-operand mode num ptr)
172 ((indirect-A) (addr+ num (instr-A-num (vector-ref core (addr+ ptr num)))))
173 ((indirect-B) (addr+ num (instr-B-num (vector-ref core (addr+ ptr num)))))
175 (let ((aux-instr (vector-ref core (addr+ ptr num))))
176 (instr-set-A-num! aux-instr (addr+ -1 (instr-A-num aux-instr)))
177 (addr+ num (instr-A-num aux-instr))))
179 (let ((aux-instr (vector-ref core (addr+ ptr num))))
180 (instr-set-B-num! aux-instr (addr+ -1 (instr-B-num aux-instr)))
181 (addr+ num (instr-B-num aux-instr))))
183 (let* ((aux-instr (vector-ref core (addr+ ptr num)))
184 (old-A-num (instr-A-num aux-instr)))
185 (instr-set-A-num! aux-instr (addr+ 1 (instr-A-num aux-instr)))
186 (addr+ num old-A-num)))
188 (let* ((aux-instr (vector-ref core (addr+ ptr num)))
189 (old-B-num (instr-B-num aux-instr)))
190 (instr-set-B-num! aux-instr (addr+ 1 (instr-B-num aux-instr)))
191 (addr+ num old-B-num)))
193 (error "Unrecognized mode" mode)))))