;;; ;;; An implementation of the Memory Array Redcode Simulator (MARS) ;;; (import (chicken io) (chicken string) (chicken random) (chicken condition) matchable) ;;; Constants ;; (define core-size 20) (define max-steps 10000) ;;; Instructions ;; (define ((make-instr opcode modifier A-mode A-num B-mode B-num name) . args) (match args (('copy n) (make-instr opcode modifier A-mode A-num B-mode B-num n)) (('copy-from! other n) (set! opcode (other 'opcode)) (set! modifier (other 'modifier)) (set! A-mode (other 'A-mode)) (set! A-num (other 'A-num)) (set! B-mode (other 'B-mode)) (set! B-num (other 'B-num)) (set! name n)) (('opcode) opcode) (('modifier) modifier) (('A-mode) A-mode) (('A-num) A-num) (('B-mode) B-mode) (('B-num) B-num) (('name) name) (('print) (print opcode "." modifier " " (mode-string A-mode) A-num ", " (mode-string B-mode) B-num (if (null? name) "" (conc " ; " name)))) (('set-opcode! x n) (set! opcode x) (set! name n)) (('set-modifier! x n) (set! modifier x) (set! name n)) (('set-A-mode! x n) (set! A-mode x) (set! name n)) (('set-A-num! x n) (set! A-num x) (set! name n)) (('set-B-mode! x n) (set! B-mode x) (set! name n)) (('set-B-num! x n) (set! B-num x) (set! name n)))) (define (mode-string mode) (case mode ((immediate) "#") ((direct) "$") ((indirect-A) "*") ((indirect-B) "@") ((pre-indirect-A) "{") ((pre-indirect-B) "<") ((post-indirect-A) "}") ((post-indirect-B) ">"))) (define initial-instruction (make-instr 'DAT 'F 'immediate 0 'immediate 0 '())) ;;; Memory setup and addressing ;; (define core (make-vector core-size '())) (define (core-get i) (vector-ref core i)) (define (core-set! i x) (vector-set! core i x)) (define (initialize-core) (let loop ((i 0)) (unless (>= i core-size) (core-set! i (initial-instruction 'copy '())) (loop (+ i 1))))) (define (dump-core) (let loop ((i 0)) (unless (>= i core-size) (print* i ":\t") ((core-get i) 'print) (loop (+ i 1))))) (define (addr+ . args) (foldl (lambda (a b) (modulo (+ a b core-size) core-size)) 0 args)) ;;; Programmes ;; (define (make-prog name instrs offset) (list name instrs offset)) (define (prog-name prog) (list-ref prog 0)) (define (prog-instrs prog) (list-ref prog 1)) (define (prog-offset prog) (list-ref prog 2)) (define (install-prog prog addr) (let loop ((ptr addr) (instrs (prog-instrs prog))) (unless (null? instrs) (core-set! ptr ((car instrs) 'copy (prog-name prog))) (loop (addr+ ptr 1) (cdr instrs)))) (make-player (prog-name prog) (addr+ addr (prog-offset prog)))) (define (can-install-prog? prog-len addr) (let loop ((ptr addr) (remaining prog-len)) (if (= remaining 0) #t (if (null? ((core-get ptr) 'name)) (loop (addr+ ptr 1) (- remaining 1)) #f)))) (define (install-progs progs) (let loop ((players '()) (progs-left progs)) (if (null? progs-left) players (let ((addr (pseudo-random-integer core-size)) (prog (car progs-left))) (if (can-install-prog? (length (prog-instrs prog)) addr) (loop (cons (install-prog prog addr) players) (cdr progs-left)) (loop players progs-left)))))) (define (make-player name ptr) (list name ptr)) (define (player-name player) (car player)) (define (player-ptrs player) (cdr player)) (define (player-set-ptrs! player ptrs) (set-cdr! player ptrs)) ;;; Executive function ;; (define (run players steps-left) (cond ((<= steps-left 0) players) ;Tie between remaining players ;; ((<= (length players) 1) players) ;There's only one player left who thus wins (else (let* ((player (car players)) (other-players (cdr players)) (ptrs (player-ptrs player)) (new-ptrs (execute-instr (car ptrs) (player-name player)))) (if (null? new-ptrs) (run other-players (- steps-left 1)) (begin (player-set-ptrs! player (append (cdr ptrs) new-ptrs)) (run (append other-players (list player)) (- steps-left 1)))))))) (define (execute-instr ptr name) (let* ((instr (core-get ptr)) (A-ptr (eval-operand (instr 'A-mode) (instr 'A-num) ptr)) (B-ptr (eval-operand (instr 'B-mode) (instr 'B-num) ptr)) (modifier (instr 'modifier))) (case (instr 'opcode) ((DAT) '()) ;Game over, man, game over! ((MOV) (if (eq? modifier 'I) ((core-get B-ptr) 'copy-from! (core-get A-ptr) name) (combine A-ptr B-ptr modifier name (lambda (x y) y))) (list (addr+ ptr 1))) ((ADD) (combine-and-store A-ptr B-ptr modifier name addr+) (list (addr+ ptr 1))) ((SUB) (combine-and-store A-ptr B-ptr modifier name (lambda (x y) (addr+ x (- y)))) (list (addr+ ptr 1))) ((MUL) (combine-and-store A-ptr B-ptr modifier name (lambda (x y) (modulo (* (addr+ x core-size) (addr+ y core-size)) core-size))) (list (addr+ ptr 1))) ((DIV) (condition-case (begin (combine-and-store A-ptr B-ptr modifier name (lambda (x y) (quotient (addr x core-size) (addr y core-size)))) (list (addr+ ptr 1))) ((exn arithmetic) '()))) ((MOD) (condition-case (begin (combine-and-store A-ptr B-ptr modifier name (lambda (x y) (remainder (addr x core-size) (addr y core-size)))) (list (addr+ ptr 1))) ((exn arithmetic) '()))) ((JMP) (list (addr+ ptr ((core-get A-ptr) 'A-num)))) ((JMZ)) ((JMN)) ((DJN)) ((SEQ CMP)) ((SNE)) ((SLT)) ((SPL)) ((NOP) (list (addr+ ptr 1))) (else (error "Unrecognised opcode" (instr 'opcode)))))) (define (combine-and-store A-ptr B-ptr modifier name f) (case modifier ((A) ((core-get B-ptr) 'set-A-num! (f ((core-get B-ptr) 'A-num) ((core-get A-ptr) 'A-num)) name)) ((B) ((core-get B-ptr) 'set-B-num! (f ((core-get B-ptr) 'B-num) ((core-get A-ptr) 'B-num)) name)) ((AB) ((core-get B-ptr) 'set-B-num! (f ((core-get B-ptr) 'B-num) ((core-get A-ptr) 'A-num)) name)) ((BA) ((core-get B-ptr) 'set-A-num! (f ((core-get B-ptr) 'A-num) ((core-get A-ptr) 'B-num)) name)) ((F I) ((core-get B-ptr) 'set-A-num! (f ((core-get B-ptr) 'A-num) ((core-get A-ptr) 'A-num))) name ((core-get B-ptr) 'set-B-num! (f ((core-get B-ptr) 'B-num) ((core-get A-ptr) 'B-num)) name)) ((X) ((core-get B-ptr) 'set-A-num! (f ((core-get B-ptr) 'A-num) ((core-get A-ptr) 'B-num)) name) ((core-get B-ptr) 'set-B-num! (f ((core-get B-ptr) 'B-num) ((core-get A-ptr) 'A-num)) name)))) (define (eval-operand mode num ptr) (addr+ ptr (case mode ((immediate) 0) ((direct) num) ((indirect-A) (addr+ num ((core-get (addr+ ptr num)) 'A-num))) ((indirect-B) (addr+ num ((core-get (addr+ ptr num)) 'B-num))) ((pre-indirect-A) (let ((aux-instr (core-get (addr+ ptr num)))) (instr-set-A-num! aux-instr (addr+ -1 (aux-instr 'A-num))) (addr+ num (aux-instr 'A-num)))) ((pre-indirect-B) (let ((aux-instr (core-get (addr+ ptr num)))) (instr-set-B-num! aux-instr (addr+ -1 (aux-instr 'B-num))) (addr+ num (aux-instr 'B-num)))) ((post-indirect-A) (let* ((aux-instr (core-get (addr+ ptr num))) (old-A-num (aux-instr 'A-num))) (instr-set-A-num! aux-instr (addr+ 1 (aux-instr 'A-num))) (addr+ num old-A-num))) ((post-indirect-B) (let* ((aux-instr (core-get (addr+ ptr num))) (old-B-num (aux-instr 'B-num))) (instr-set-B-num! aux-instr (addr+ 1 (aux-instr 'B-num))) (addr+ num old-B-num))) (else (error "Unrecognized mode" mode))))) ;;; TEST CODE (define addressing-test (make-prog 'at (list (make-instr 'DAT 'F 'immediate 42 'immediate 53 'at) (make-instr 'DAT 'F 'immediate 123 'immediate 256 'at) (make-instr 'MOV 'A 'indirect-B 4 'direct 7 'at) (make-instr 'NOP 'I 'immediate 0 'immediate 0 'at) (make-instr 'NOP 'I 'immediate 0 'immediate 0 'at) (make-instr 'NOP 'I 'immediate 0 'immediate 0 'at) (make-instr 'DAT 'F 'immediate -5 'immediate -6 'at)) 2)) (define imp (make-prog 'imp (list (make-instr 'MOV 'I 'direct 0 'direct 1 'imp)) 0)) (define dwarf (make-prog 'dwarf (list (make-instr 'DAT 'F 'immediate 0 'immediate -1 'dwarf) (make-instr 'ADD 'AB 'immediate 5 'direct -1 'dwarf) (make-instr 'MOV 'I 'direct -2 'indirect-B -2 'dwarf) (make-instr 'JMP 'I 'immediate -2 'immediate 0 'dwarf)) 1)) (initialize-core) (define players (install-progs (list dwarf imp))) (dump-core)