2 ;;; An implementation of the Memory Array Redcode Simulator (MARS)
16 (define max-steps 10000)
22 (define (make-instr opcode modifier A-mode A-num B-mode B-num name)
23 (list opcode modifier A-mod A-num B-mode B-num name))
25 (define (instr-opcode instr) (list-ref instr 0))
26 (define (instr-modifier instr) (list-ref instr 1))
27 (define (instr-A-mode instr) (list-ref instr 2))
28 (define (instr-A-num instr) (list-ref instr 3))
29 (define (instr-B-mode instr) (list-ref instr 4))
30 (define (instr-B-num instr) (list-ref instr 5))
31 (define (instr-name instr) (list-ref instr 6))
33 (define (mode->string mode)
39 ((pre-indirect-A) "{")
40 ((pre-indirect-B) "<")
41 ((post-indirect-A) "}")
42 ((post-indirect-B) ">")
44 (error "Unknown mode."))))
46 (define (instr->string opcode modifier A-mode A-num B-mode B-num name)
49 " " (mode->string A-mode) A-num
50 " " (mode->string B-mode) B-num
53 (define initial-instruction
54 (make-instr 'DAT 'F 'immediate 0 'immediate 0 '()))
57 ;;; Memory setup and addressing
60 (define (make-core core-size opcode modifier A-mode A-num B-mode B-num)
61 (let ((opcodes (make-vector core-size opcode))
62 (modifiers (make-vector core-size modifier))
63 (A-modes (make-vector core-size A-mode))
64 (A-nums (make-vector core-size A-num))
65 (B-modes (make-vector core-size B-mode))
66 (B-nums (make-vector core-size B-num))
67 (names (make-vector core-size '())))
71 (vector-set! opcodes j (vector-ref opcodes i))
72 (vector-set! modifiers j (vector-ref modifiers i))
73 (vector-set! A-modes j (vector-ref A-modes i))
74 (vector-set! A-nums j (vector-ref A-nums i))
75 (vector-set! B-modes j (vector-ref B-modes i))
76 (vector-set! B-nums j (vector-ref B-nums i))
77 (vector-set! names j n))
78 ((i 'copy-from-instr! instr)
79 (vector-set! opcodes i (instr-opcode instr))
80 (vector-set! modifiers i (instr-modifier instr))
81 (vector-set! A-mode i (instr-A-mode instr))
82 (vector-set! A-num i (instr-A-num instr))
83 (vector-set! B-mode i (instr-B-mode instr))
84 (vector-set! B-num i (instr-B-num instr))
85 (vector-set! names i (instr-name instr)))
86 ((i 'opcode) (vector-ref opcodes i))
87 ((i 'modifier) (vector-ref modifiers i))
88 ((i 'A-mode) (vector-ref A-modes i))
89 ((i 'A-num) (vector-ref A-nums i))
90 ((i 'B-mode) (vector-ref B-modes i))
91 ((i 'B-num) (vector-ref B-nums i))
92 ((i 'name) (vector-ref names i))
93 ((i 'set-opcode! x n) (vector-set! opcodes i x) (vector-set! names i n))
94 ((i 'set-modifier! x n) (vector-set! modifiers i x) (vector-set! names i n))
95 ((i 'set-A-mode! x n) (vector-set! A-modes i x) (vector-set! names i n))
96 ((i 'set-A-num! x n) (vector-set! A-nums i x) (vector-set! names i n))
97 ((i 'set-B-mode! x n) (vector-set! B-modes i x) (vector-set! names i n))
98 ((i 'set-B-num! x n) (vector-set! B-nums i x) (vector-set! names i n))
101 (unless (>= i core-size))
103 (instr->string (vector-ref opcodes i)
104 (vector-ref modifiers i)
105 (vector-ref A-modes i)
106 (vector-ref A-nums i)
107 (vector-ref B-modes i)
108 (vector-ref B-nums i)
109 (vector-ref names i))))))))
111 (define (addr+ . args)
113 (modulo (+ a b core-size) core-size))
119 (define (make-prog name instrs offset)
120 (list name instrs offset))
122 (define (prog-name prog) (list-ref prog 0))
123 (define (prog-instrs prog) (list-ref prog 1))
124 (define (prog-offset prog) (list-ref prog 2))
126 (define (install-prog core prog addr)
127 (let loop ((ptr addr)
128 (instrs (prog-instrs prog)))
129 (unless (null? instrs)
130 (core ptr 'copy-from-instr! (car instrs))
131 (loop (addr+ ptr 1) (cdr instrs))))
132 (make-player (prog-name prog)
133 (addr+ addr (prog-offset prog))))
135 (define (can-install-prog? core prog-len addr)
136 (let loop ((ptr addr)
137 (remaining prog-len))
140 (if (null? (core ptr 'name))
145 (define (install-progs core progs)
146 (let loop ((players '())
148 (if (null? progs-left)
150 (let ((addr (pseudo-random-integer core-size))
151 (prog (car progs-left)))
152 (if (can-install-prog? core (length (prog-instrs prog)) addr)
153 (loop (cons (install-prog core prog addr) players)
155 (loop players progs-left))))))
157 (define (make-player name ptr)
160 (define (player-name player) (car player))
161 (define (player-ptrs player) (cdr player))
163 (define (player-set-ptrs! player ptrs)
164 (set-cdr! player ptrs))
167 ;;; Executive function
170 (define (run players steps-left)
172 ((<= steps-left 0) players) ;Tie between remaining players
173 ;; ((<= (length players) 1) players) ;There's only one player left who thus wins
175 (let* ((player (car players))
176 (other-players (cdr players))
177 (ptrs (player-ptrs player))
178 (new-ptrs (execute-instr (car ptrs) (player-name player))))
180 (run other-players (- steps-left 1))
182 (player-set-ptrs! player (append (cdr ptrs) new-ptrs))
183 (run (append other-players (list player)) (- steps-left 1))))))))
185 (define (execute-instr ptr name)
186 (let* ((instr (core-get ptr))
187 (A-ptr (eval-operand (instr 'A-mode) (instr 'A-num) ptr))
188 (B-ptr (eval-operand (instr 'B-mode) (instr 'B-num) ptr))
189 (modifier (instr 'modifier)))
190 (case (instr 'opcode)
192 '()) ;Game over, man, game over!
194 (if (eq? modifier 'I)
195 ((core-get B-ptr) 'copy-from! (core-get A-ptr) name)
196 (combine A-ptr B-ptr modifier name (lambda (x y) y)))
197 (list (addr+ ptr 1)))
199 (combine-and-store A-ptr B-ptr modifier name addr+)
200 (list (addr+ ptr 1)))
202 (combine-and-store A-ptr B-ptr modifier name
203 (lambda (x y) (addr+ x (- y))))
204 (list (addr+ ptr 1)))
206 (combine-and-store A-ptr B-ptr modifier name
207 (lambda (x y) (modulo (* (addr+ x core-size)
210 (list (addr+ ptr 1)))
214 (combine-and-store A-ptr B-ptr modifier name
215 (lambda (x y) (quotient (addr x core-size)
216 (addr y core-size))))
217 (list (addr+ ptr 1)))
218 ((exn arithmetic) '())))
222 (combine-and-store A-ptr B-ptr modifier name
223 (lambda (x y) (remainder (addr x core-size)
224 (addr y core-size))))
225 (list (addr+ ptr 1)))
226 ((exn arithmetic) '())))
228 (list (addr+ ptr ((core-get A-ptr) 'A-num))))
230 (list (addr+ ptr (if (instr-zero? B-ptr modifier #f)
231 ((core-get A-ptr) 'A-num)
234 (list (addr+ ptr (if (not (instr-zero? B-ptr modifier #f))
235 ((core-get A-ptr) 'A-num)
238 (list (addr+ ptr (if (not (instr-zero? B-ptr modifier #t))
239 ((core-get A-ptr) 'A-num)
242 (list (addr+ ptr (if (compare-instrs A-ptr B-ptr modifier =) 2 1))))
244 (list (addr+ ptr (if (compare-instrs A-ptr B-ptr modifier =) 1 2))))
246 (list (addr+ ptr (if (compare-instrs A-ptr B-ptr modifier <) 2 1))))
248 (list (addr+ ptr 1) (addr+ ptr ((core-get A-ptr) 'A-num))))
250 (list (addr+ ptr 1)))
252 (error "Unrecognised opcode" (instr 'opcode))))))
254 (define (compare-instrs A-ptr B-ptr modifier test)
255 (let ((A-instr (core-get A-ptr))
256 (B-instr (core-get B-ptr)))
258 ((A) (test (A-instr 'A-num) (B-instr 'A-num)))
259 ((B) (test (A-instr 'B-num) (B-instr 'B-num)))
260 ((AB) (test (A-instr 'A-num) (B-instr 'B-num)))
261 ((BA) (test (A-instr 'B-num) (B-instr 'A-num)))
263 (test (A-instr 'A-num) (B-instr 'A-num))
264 (test (A-instr 'B-num) (B-instr 'B-num))))
266 (test (A-instr 'A-num) (B-instr 'B-num))
267 (test (A-instr 'B-num) (B-instr 'A-num))))
271 (eq? (A-instr 'opcode) (B-instr 'opcode))
272 (eq? (A-instr 'modifier) (B-instr 'modifier))
273 (eq? (A-instr 'A-mode) (B-instr 'B-mode))
274 (eq? (A-instr 'B-mode) (B-instr 'A-mode)))
276 (test (A-instr 'A-num) (B-instr 'B-num))
277 (test (A-instr 'B-num) (B-instr 'A-num)))))))
279 (define (instr-zero? ptr modifier decrement)
280 (let ((instr (core-get ptr)))
283 (if decrement (instr 'set-A-num! (addr+ (instr 'A-num) -1)))
284 (= 0 (instr 'A-num)))
286 (if decrement (instr 'set-B-num! (addr+ (instr 'B-num) -1)))
287 (= 0 (instr 'B-num)))
291 (instr 'set-A-num! (addr+ (instr 'A-num) -1))
292 (instr 'set-B-num! (addr+ (instr 'B-num) -1))))
293 (and (= 0 (instr 'A-num))
294 (= 0 (instr 'B-num)))))))
296 (define (combine-and-store A-ptr B-ptr modifier name f)
298 ((A) ((core-get B-ptr) 'set-A-num!
299 (f ((core-get B-ptr) 'A-num) ((core-get A-ptr) 'A-num)) name))
300 ((B) ((core-get B-ptr) 'set-B-num!
301 (f ((core-get B-ptr) 'B-num) ((core-get A-ptr) 'B-num)) name))
302 ((AB) ((core-get B-ptr) 'set-B-num!
303 (f ((core-get B-ptr) 'B-num) ((core-get A-ptr) 'A-num)) name))
304 ((BA) ((core-get B-ptr) 'set-A-num!
305 (f ((core-get B-ptr) 'A-num) ((core-get A-ptr) 'B-num)) name))
306 ((F I) ((core-get B-ptr) 'set-A-num!
307 (f ((core-get B-ptr) 'A-num) ((core-get A-ptr) 'A-num))) name
308 ((core-get B-ptr) 'set-B-num!
309 (f ((core-get B-ptr) 'B-num) ((core-get A-ptr) 'B-num)) name))
310 ((X) ((core-get B-ptr) 'set-A-num!
311 (f ((core-get B-ptr) 'A-num) ((core-get A-ptr) 'B-num)) name)
312 ((core-get B-ptr) 'set-B-num!
313 (f ((core-get B-ptr) 'B-num) ((core-get A-ptr) 'A-num)) name))))
315 (define (eval-operand mode num ptr)
320 ((indirect-A) (addr+ num ((core-get (addr+ ptr num)) 'A-num)))
321 ((indirect-B) (addr+ num ((core-get (addr+ ptr num)) 'B-num)))
323 (let ((aux-instr (core-get (addr+ ptr num))))
324 ((aux-instr set-A-num! (addr+ -1 (aux-instr 'A-num))))
325 (addr+ num (aux-instr 'A-num))))
327 (let ((aux-instr (core-get (addr+ ptr num))))
328 (aux-instr set-B-num!(addr+ -1 (aux-instr 'B-num)))
329 (addr+ num (aux-instr 'B-num))))
331 (let* ((aux-instr (core-get (addr+ ptr num)))
332 (old-A-num (aux-instr 'A-num)))
333 (aux-instr set-A-num! (addr+ 1 (aux-instr 'A-num)))
334 (addr+ num old-A-num)))
336 (let* ((aux-instr (core-get (addr+ ptr num)))
337 (old-B-num (aux-instr 'B-num)))
338 (aux-instr set-B-num! (addr+ 1 (aux-instr 'B-num)))
339 (addr+ num old-B-num)))
341 (error "Unrecognized mode" mode)))))
345 (define addressing-test
347 (make-instr 'DAT 'F 'immediate 42 'immediate 53 'at)
348 (make-instr 'DAT 'F 'immediate 123 'immediate 256 'at)
349 (make-instr 'MOV 'A 'indirect-B 4 'direct 7 'at)
350 (make-instr 'NOP 'I 'immediate 0 'immediate 0 'at)
351 (make-instr 'NOP 'I 'immediate 0 'immediate 0 'at)
352 (make-instr 'NOP 'I 'immediate 0 'immediate 0 'at)
353 (make-instr 'DAT 'F 'immediate -5 'immediate -6 'at)) 2))
356 (make-prog 'imp (list (make-instr 'MOV 'I 'direct 0 'direct 1 'imp)) 0))
359 (make-prog 'dwarf (list
360 (make-instr 'DAT 'F 'immediate 0 'immediate -1 'dwarf)
361 (make-instr 'ADD 'AB 'immediate 5 'direct -1 'dwarf)
362 (make-instr 'MOV 'I 'direct -2 'indirect-B -2 'dwarf)
363 (make-instr 'JMP 'I 'immediate -2 'immediate 0 'dwarf)) 1))
366 (define players (install-progs (list dwarf imp)))