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(defpackage #:intcode
(:use :cl)
(:export :run :parse))
(in-package #:intcode)
;;; Interpreter
(defstruct opcode
instr
param-count
param-modes
last-outputs-p)
(defconstant +instr-add+ 1)
(defconstant +instr-mul+ 2)
(defconstant +instr-set+ 3)
(defconstant +instr-out+ 4)
(defconstant +instr-jt+ 5)
(defconstant +instr-jn+ 6)
(defconstant +instr-le+ 7)
(defconstant +instr-eq+ 8)
(defconstant +instr-quit+ 99)
(defparameter *handlers* (make-array 100))
;; Interpreter State
(defparameter *ip* 0)
(defparameter *inputs* nil)
(defparameter *outputs* nil)
(defparameter *ram* nil)
(defun run (ram &optional inputs)
(setq *ip* 0 *inputs* inputs *outputs* nil *ram* ram)
(loop
(let* ((opcode (decode-next-opcode))
(handler (aref *handlers* (opcode-instr opcode))))
(when (eq (apply handler (fetch-arguments opcode)) 'quit)
(return-from run (nreverse *outputs*))))))
(defun decode-next-opcode ()
(let* ((opcode
(aref *ram* *ip*))
(instr
(mod opcode 100))
(param-count
(ecase instr
(#.+instr-add+ 3)
(#.+instr-mul+ 3)
(#.+instr-set+ 1)
(#.+instr-out+ 1)
(#.+instr-jt+ 2)
(#.+instr-jn+ 2)
(#.+instr-le+ 3)
(#.+instr-eq+ 3)
(#.+instr-quit+ 0)))
(param-modes
(make-array 3 :initial-contents
(list (mod (floor opcode 100) 10)
(mod (floor opcode 1000) 10)
(mod (floor opcode 10000) 10))))
(last-outputs-p
(member instr '(#.+instr-add+ #.+instr-mul+ #.+instr-set+
#.+instr-le+ #.+instr-eq+))))
(make-opcode :instr instr
:param-count param-count
:param-modes param-modes
:last-outputs-p last-outputs-p)))
(defun fetch-arguments (opcode)
(when (opcode-last-outputs-p opcode)
(setf (aref (opcode-param-modes opcode)
(1- (opcode-param-count opcode)))
1))
(loop for i from 1 to (opcode-param-count opcode)
collect (ecase (aref (opcode-param-modes opcode) (1- i))
(0 (aref *ram* (aref *ram* (+ *ip* i))))
(1 (aref *ram* (+ *ip* i))))))
;;; Instructions
(defmacro definstruction (name (&rest params) &body forms)
(let ((instr (intern (format nil "+INSTR-~:@(~a~)+" name))))
`(setf (aref *handlers* ,instr)
(lambda ,params
(case (progn ,@forms)
('jumpedp nil)
('quit 'quit)
(otherwise (incf *ip* ,(1+ (length params)))))))))
(definstruction add (x y dst)
(setf (aref *ram* dst) (+ x y)))
(definstruction mul (x y dst)
(setf (aref *ram* dst) (* x y)))
(definstruction set (dst)
(setf (aref *ram* dst) (car *inputs*))
(setq *inputs* (cdr *inputs*)))
(definstruction out (x)
(push x *outputs*))
(definstruction jt (x addr)
(unless (zerop x)
(setq *ip* addr)
'jumpedp))
(definstruction jn (x addr)
(when (zerop x)
(setq *ip* addr)
'jumpedp))
(definstruction le (x y dst)
(setf (aref *ram* dst) (bool->int (< x y))))
(definstruction eq (x y dst)
(setf (aref *ram* dst) (bool->int (= x y))))
(definstruction quit ()
'quit)
;;; Input Parsing
(defun parse (filename)
(with-open-file (stream filename)
(let ((contents (make-string (file-length stream))))
(read-sequence contents stream)
(extract-numbers-from-string contents))))
(defun extract-numbers-from-string (string)
(loop for comma-pos = (position-if #'commap string)
collect (parse-integer (subseq string 0 comma-pos)) into numbers
unless comma-pos
return (coerce numbers 'vector)
do (setq string (subseq string (1+ comma-pos)))))
;;; Helper Functions
(defun commap (char)
(char= char #\,))
(defun bool->int (bool)
(if bool 1 0))
(defun try-aref (array &rest subscripts)
(loop for i in subscripts
for j in (array-dimensions array)
unless (< -1 i j)
return nil
finally (return (apply #'aref array subscripts))))
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