Drafted operand evaluation procedure.

[jars.git] / mars.scm

diff --git a/mars.scm b/mars.scm
index 57e3e13..b1aa9db 100644 (file)
--- a/mars.scm
+++ b/mars.scm
@@ -2,6 +2,10 @@
 ;;; An implementation of the Memory Array Redcode Simulator (MARS)
 ;;;
 
 ;;; An implementation of the Memory Array Redcode Simulator (MARS)
 ;;;
 

+(import (chicken io)
+        (chicken string)
+        matchable)
+

 ;;; Constants
 ;;
 
 ;;; Constants
 ;;
 


@@ -18,7 +22,13 @@
 ;;; Instructions
 ;;
 
 ;;; Instructions
 ;;
 

-(define (make-instr opcode modifier addrA modeA addrB modeB))
+(define (make-instr opcode modifier A-mode A-num B-mode B-num))
+(define (instr-opcode instr) (list-ref instr 0))
+(define (instr-modifier instr) (list-ref instr 1))
+(define (instr-A-mode instr) (list-ref instr 2))
+(define (instr-A-num instr) (list-ref instr 3))
+(define (instr-B-mode instr) (list-ref instr 4))
+(define (instr-B-num instr) (list-ref instr 5))

 
 
 ;;; Players
 
 
 ;;; Players


@@ -40,24 +50,67 @@
 ;;; Main loop
 ;;
 
 ;;; Main loop
 ;;
 

-(define (list-rot l)
-  (if (> (length l) 1)
-      (append (cdr l) (list (car l)))
-      l))
-
-(define (run playerA playerB step)
+(define (run players step)

   (cond
   (cond

-   ((> step max-steps) 'tie)
-   ((null? (player-ptrs playerA) playerB))
-   ((null? (player-ptrs playerB) playerA))
+   ((> step max-steps) players)      ;Tie between remaining players
+   ((<= (length players) 1) players) ;There's only one player left who thus wins

    (else
    (else

-    (let ((ptrs (player-ptrs playerA)))
-      (player-set-ptrs! (append (cdr ptrs)
-                                (execute-instr (car ptrs)))))
-    (run playerB player A (+ step 1)))))
+    (let ((player (car players))
+          (other-players (cdr players))
+          (ptrs (player-ptrs player)))
+      (let ((new-ptrs (execute-instr (car ptrs))))
+        (if (null? new-ptrs)
+            (run other-players (+ step 1))
+            (begin
+              (player-set-ptrs! (append (cdr ptrs) new-ptrs))
+              (run (append other-players (list player)) (+ step 1)))))))))

 
 (define (execute-instr ptr)
 
 (define (execute-instr ptr)

-  (let ((instr (vector-ref core ptr)))
-    (match instr
-      ())))
+  (let* ((instr (vector-ref core ptr))
+         (A-pointer (eval-operand (instr-A-mode instr) (instr-A-num) ptr))
+         (B-pointer (eval-operand (instr-B-mode instr) (instr-B-num) ptr)))
+    (case (instr-opcode instr)
+      ((DAT))
+      ((MOV))
+      ((ADD))
+      ((SUB))
+      ((MUL))
+      ((DIV))
+      ((MOD))
+      ((JMP))
+      ((JMN))
+      ((DJN))
+      ((SEQ CMP))
+      ((SNE))
+      ((SLT))
+      ((SPL))
+      ((NOP))
+      (else
+       (error "Unrecognised opcode" (instr-opcode instr))))))

                
                

+(define (eval-operand mode num ptr)
+  (case mode
+    ((immediate) 0)
+    ((direct) num)
+    ((indirect-A) (+ num (instr-A-num (vector-ref core (+ ptr num)))))
+    ((indirect-B) (+ num (instr-B-num (vector-ref core (+ ptr num)))))
+    ((pre-indirect-A)
+     (let ((aux-instr (vector-ref core (+ ptr num))))
+       (instr-set-A-num! aux-instr (- 1 (instr-A-num aux-instr)))
+       (+ num (instr-A-num aux-instr))))
+    ((pre-indirect-B)
+     (let ((aux-instr (vector-ref core (+ ptr num))))
+       (instr-set-B-num! aux-instr (- 1 (instr-B-num aux-instr)))
+       (+ num (instr-B-num aux-instr))))
+    ((post-indirect-A)
+     (let* ((aux-instr (vector-ref core (+ ptr num)))
+            (old-A-num (instr-A-num aux-instr)))
+       (instr-set-A-num! aux-instr (+ 1 (instr-A-num aux-instr)))
+       (+ num old-A-num)))
+    ((post-indirect-B)
+     (let* ((aux-instr (vector-ref core (+ ptr num)))
+            (old-B-num (instr-B-num aux-instr)))
+       (instr-set-B-num! aux-instr (+ 1 (instr-B-num aux-instr)))
+       (+ num old-B-num)))
+    (else
+     (error "Unrecognized mode" mode))))