;;
(define core (make-vector core-size '()))
-
+(define (addr+ . args)
+ (foldl (lambda (a b)
+ (modulo (+ a b core-size) core-size))
+ 0 args))
;;; Instructions
;;
(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))
(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))))