X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?p=jars.git;a=blobdiff_plain;f=mars.scm;h=f2e3d99a982474520cbdc9b6be3ce875c195b396;hp=2f4db9de8672d3b44b66020ad03437e68253f1d5;hb=871e290a730e6f7a2e6c7dd8ffb754f2007d5f74;hpb=d77eebde986b6bd5e5c25c40523920dfcac96f13

diff --git a/mars.scm b/mars.scm
index 2f4db9d..f2e3d99 100644
--- a/mars.scm
+++ b/mars.scm
@@ -17,7 +17,10 @@
 ;;
 
 (define core (make-vector core-size '()))
-
+(define (addr+ . args)
+  (foldl (lambda (a b)
+           (modulo (+ a b core-size) core-size))
+         0 args))
 
 ;;; Instructions
 ;;
@@ -67,10 +70,11 @@
 
 (define (execute-instr ptr)
   (let* ((instr (vector-ref core ptr))
-         (A-operand (eval-operand (instr-A-mode instr) (instr-A-num) ptr))
-         (B-operand (eval-operand (instr-B-mode instr) (instr-B-num) 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))
+         (modifier (instr-modifier instr)))
     (case (instr-opcode instr)
-      ((DAT))
+      ((DAT) '()) ;Game over, man, game over!
       ((MOV))
       ((ADD))
       ((SUB))
@@ -90,11 +94,27 @@
                
 (define (eval-operand mode num ptr)
   (case mode
-    ((immediate))
-    ((direct))
-    ((indirect-A))
-    ((indirect-B))
-    ((pre-indirect-A))
-    ((pre-indirect-B))
-    ((post-indirect-A))
-    ((post-indirect-B))))
+    ((immediate) 0)
+    ((direct) num)
+    ((indirect-A) (addr+ num (instr-A-num (vector-ref core (addr+ ptr num)))))
+    ((indirect-B) (addr+ num (instr-B-num (vector-ref core (addr+ ptr num)))))
+    ((pre-indirect-A)
+     (let ((aux-instr (vector-ref core (addr+ ptr num))))
+       (instr-set-A-num! aux-instr (addr+ -1 (instr-A-num aux-instr)))
+       (addr+ num (instr-A-num aux-instr))))
+    ((pre-indirect-B)
+     (let ((aux-instr (vector-ref core (addr+ ptr num))))
+       (instr-set-B-num! aux-instr (addr+ -1 (instr-B-num aux-instr)))
+       (addr+ num (instr-B-num aux-instr))))
+    ((post-indirect-A)
+     (let* ((aux-instr (vector-ref core (addr+ ptr num)))
+            (old-A-num (instr-A-num aux-instr)))
+       (instr-set-A-num! aux-instr (addr+ 1 (instr-A-num aux-instr)))
+       (addr+ num old-A-num)))
+    ((post-indirect-B)
+     (let* ((aux-instr (vector-ref core (addr+ ptr num)))
+            (old-B-num (instr-B-num aux-instr)))
+       (instr-set-B-num! aux-instr (addr+ 1 (instr-B-num aux-instr)))
+       (addr+ num old-B-num)))
+    (else
+     (error "Unrecognized mode" mode))))