2 ;;; An implementation of the Memory Array Redcode Simulator (MARS)
15 (define max-steps 10000)
21 (define ((make-instr opcode modifier A-mode A-num B-mode B-num name) . args)
23 (('copy n) (make-instr opcode modifier A-mode A-num B-mode B-num n))
24 (('copy-from! other n)
25 (set! opcode (other 'opcode))
26 (set! modifier (other 'modifier))
27 (set! A-mode (other 'A-mode))
28 (set! A-num (other 'A-num))
29 (set! B-mode (other 'B-mode))
30 (set! B-num (other 'B-num))
33 (('modifier) modifier)
39 (('print) (print opcode
41 " " (mode-string A-mode) A-num
42 ", " (mode-string B-mode) B-num
43 (if (null? name) "" (conc " ; " name))))
44 (('set-opcode! x n) (set! opcode x) (set! name n))
45 (('set-modifier! x n) (set! modifier x) (set! name n))
46 (('set-A-mode! x n) (set! A-mode x) (set! name n))
47 (('set-A-num! x n) (set! A-num x) (set! name n))
48 (('set-B-mode! x n) (set! B-mode x) (set! name n))
49 (('set-B-num! x n) (set! B-num x) (set! name n))))
51 (define (mode-string mode)
57 ((pre-indirect-A) "{")
58 ((pre-indirect-B) "<")
59 ((post-indirect-A) "}")
60 ((post-indirect-B) ">")))
62 (define initial-instruction
63 (make-instr 'DAT 'F 'immediate 0 'immediate 0 '()))
66 ;;; Memory setup and addressing
69 (define core (make-vector core-size '()))
74 (define (core-set! i x)
75 (vector-set! core i x))
77 (define (initialize-core)
79 (unless (>= i core-size)
80 (core-set! i (initial-instruction 'copy '()))
85 (unless (>= i core-size)
90 (define (addr+ . args)
92 (modulo (+ a b core-size) core-size))
98 (define (make-prog name instrs offset)
99 (list name instrs offset))
101 (define (prog-name prog) (list-ref prog 0))
102 (define (prog-instrs prog) (list-ref prog 1))
103 (define (prog-offset prog) (list-ref prog 2))
105 (define (install-prog prog addr)
106 (let loop ((ptr addr)
107 (instrs (prog-instrs prog)))
108 (unless (null? instrs)
109 (core-set! ptr ((car instrs) 'copy (prog-name prog)))
110 (loop (addr+ ptr 1) (cdr instrs))))
111 (make-player (prog-name prog)
112 (addr+ addr (prog-offset prog))))
114 (define (can-install-prog? prog-len addr)
115 (let loop ((ptr addr)
116 (remaining prog-len))
119 (if (null? ((core-get ptr) 'name))
124 (define (install-progs progs)
125 (let loop ((players '())
127 (if (null? progs-left)
129 (let ((addr (pseudo-random-integer core-size))
130 (prog (car progs-left)))
131 (if (can-install-prog? (length (prog-instrs prog)) addr)
132 (loop (cons (install-prog prog addr) players)
134 (loop players progs-left))))))
136 (define (make-player name ptr)
139 (define (player-name player) (car player))
140 (define (player-ptrs player) (cdr player))
142 (define (player-set-ptrs! player ptrs)
143 (set-cdr! player ptrs))
146 ;;; Executive function
149 (define (run players steps-left)
151 ((<= steps-left 0) players) ;Tie between remaining players
152 ;; ((<= (length players) 1) players) ;There's only one player left who thus wins
154 (let* ((player (car players))
155 (other-players (cdr players))
156 (ptrs (player-ptrs player))
157 (new-ptrs (execute-instr (car ptrs) (player-name player))))
159 (run other-players (- steps-left 1))
161 (player-set-ptrs! player (append (cdr ptrs) new-ptrs))
162 (run (append other-players (list player)) (- steps-left 1))))))))
164 (define (execute-instr ptr name)
165 (let* ((instr (core-get ptr))
166 (A-ptr (eval-operand (instr 'A-mode) (instr 'A-num) ptr))
167 (B-ptr (eval-operand (instr 'B-mode) (instr 'B-num) ptr))
168 (modifier (instr 'modifier)))
169 (case (instr 'opcode)
171 '()) ;Game over, man, game over!
173 (if (eq? modifier 'I)
174 ((core-get B-ptr) 'copy-from! (core-get A-ptr) name)
175 (combine A-ptr B-ptr modifier name (lambda (x y) y)))
176 (list (addr+ ptr 1)))
178 (combine-and-store A-ptr B-ptr modifier name addr+)
179 (list (addr+ ptr 1)))
181 (combine-and-store A-ptr B-ptr modifier name
182 (lambda (x y) (addr+ x (- y))))
183 (list (addr+ ptr 1)))
185 (combine-and-store A-ptr B-ptr modifier name
186 (lambda (x y) (modulo (* (addr+ x core-size)
189 (list (addr+ ptr 1)))
193 (combine-and-store A-ptr B-ptr modifier name
194 (lambda (x y) (quotient (addr x core-size)
195 (addr y core-size))))
196 (list (addr+ ptr 1)))
197 ((exn arithmetic) '())))
201 (combine-and-store A-ptr B-ptr modifier name
202 (lambda (x y) (remainder (addr x core-size)
203 (addr y core-size))))
204 (list (addr+ ptr 1)))
205 ((exn arithmetic) '())))
207 (list (addr+ ptr ((core-get A-ptr) 'A-num))))
215 ((NOP) (list (addr+ ptr 1)))
217 (error "Unrecognised opcode" (instr 'opcode))))))
219 (define (combine-and-store A-ptr B-ptr modifier name f)
221 ((A) ((core-get B-ptr) 'set-A-num!
222 (f ((core-get B-ptr) 'A-num) ((core-get A-ptr) 'A-num)) name))
223 ((B) ((core-get B-ptr) 'set-B-num!
224 (f ((core-get B-ptr) 'B-num) ((core-get A-ptr) 'B-num)) name))
225 ((AB) ((core-get B-ptr) 'set-B-num!
226 (f ((core-get B-ptr) 'B-num) ((core-get A-ptr) 'A-num)) name))
227 ((BA) ((core-get B-ptr) 'set-A-num!
228 (f ((core-get B-ptr) 'A-num) ((core-get A-ptr) 'B-num)) name))
229 ((F I) ((core-get B-ptr) 'set-A-num!
230 (f ((core-get B-ptr) 'A-num) ((core-get A-ptr) 'A-num))) name
231 ((core-get B-ptr) 'set-B-num!
232 (f ((core-get B-ptr) 'B-num) ((core-get A-ptr) 'B-num)) name))
233 ((X) ((core-get B-ptr) 'set-A-num!
234 (f ((core-get B-ptr) 'A-num) ((core-get A-ptr) 'B-num)) name)
235 ((core-get B-ptr) 'set-B-num!
236 (f ((core-get B-ptr) 'B-num) ((core-get A-ptr) 'A-num)) name))))
238 (define (eval-operand mode num ptr)
243 ((indirect-A) (addr+ num ((core-get (addr+ ptr num)) 'A-num)))
244 ((indirect-B) (addr+ num ((core-get (addr+ ptr num)) 'B-num)))
246 (let ((aux-instr (core-get (addr+ ptr num))))
247 (instr-set-A-num! aux-instr (addr+ -1 (aux-instr 'A-num)))
248 (addr+ num (aux-instr 'A-num))))
250 (let ((aux-instr (core-get (addr+ ptr num))))
251 (instr-set-B-num! aux-instr (addr+ -1 (aux-instr 'B-num)))
252 (addr+ num (aux-instr 'B-num))))
254 (let* ((aux-instr (core-get (addr+ ptr num)))
255 (old-A-num (aux-instr 'A-num)))
256 (instr-set-A-num! aux-instr (addr+ 1 (aux-instr 'A-num)))
257 (addr+ num old-A-num)))
259 (let* ((aux-instr (core-get (addr+ ptr num)))
260 (old-B-num (aux-instr 'B-num)))
261 (instr-set-B-num! aux-instr (addr+ 1 (aux-instr 'B-num)))
262 (addr+ num old-B-num)))
264 (error "Unrecognized mode" mode)))))
268 (define addressing-test
270 (make-instr 'DAT 'F 'immediate 42 'immediate 53 'at)
271 (make-instr 'DAT 'F 'immediate 123 'immediate 256 'at)
272 (make-instr 'MOV 'A 'indirect-B 4 'direct 7 'at)
273 (make-instr 'NOP 'I 'immediate 0 'immediate 0 'at)
274 (make-instr 'NOP 'I 'immediate 0 'immediate 0 'at)
275 (make-instr 'NOP 'I 'immediate 0 'immediate 0 'at)
276 (make-instr 'DAT 'F 'immediate -5 'immediate -6 'at)) 2))
279 (make-prog 'imp (list (make-instr 'MOV 'I 'direct 0 'direct 1 'imp)) 0))
282 (make-prog 'dwarf (list
283 (make-instr 'DAT 'F 'immediate 0 'immediate -1 'dwarf)
284 (make-instr 'ADD 'AB 'immediate 5 'direct -1 'dwarf)
285 (make-instr 'MOV 'I 'direct -2 'indirect-B -2 'dwarf)
286 (make-instr 'JMP 'I 'immediate -2 'immediate 0 'dwarf)) 1))
289 (define players (install-progs (list dwarf imp)))