X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?p=jars.git;a=blobdiff_plain;f=mars.scm;h=b1aa9db8f03f1bd52c38fbce981ca6423de07d0a;hp=c77e2d3142f9338b0a90715aa749af07858ab316;hb=707bcb205c185815e2b94ab3fca5f769afb58264;hpb=8c9a5e7af566f647f2acb58dabe558008964f27f

diff --git a/mars.scm b/mars.scm
index c77e2d3..b1aa9db 100644
--- a/mars.scm
+++ b/mars.scm
@@ -22,7 +22,13 @@
 ;;; 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
@@ -46,20 +52,23 @@
 
 (define (run players step)
   (cond
-   ((> step max-steps) players) ;Tie between remaining players
-   ((null? players) '())        ;Somehow we have no players remaining
+   ((> step max-steps) 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)))
-      (if (null? ptrs)
-          (run other-players (+ step 1))  ;Player is out
-          (let* ((ptrs (player-ptrs player))
-                 (new-ptrs (execute-instr (car ptrs))))
-            (player-set-ptrs! (append (cdr ptrs) new-ptrs))
-            (run (append other-players (list player)) (+ step 1))))))))
+          (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)
-  (let ((instr (vector-ref core ptr)))
+  (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))
@@ -79,3 +88,29 @@
       (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))))