Self contained program parsing

1 files changed, 28 insertions, 17 deletions

diff --git a/6502.lisp b/6502.lisp
index a7982d8..1e9c7d4 100644
--- a/6502.lisp
+++ b/6502.lisp
@@ -18,8 +18,25 @@ License along with this library; if not, write to the Free Software
 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 |#
 
-;; Every instruction, its decimal opcode, and the
-;; usable addressing modes.
+;;; List of addressing modes.
+(setf
+ *addressing-modes*
+ '(immediate
+   absolute 
+   zero-page 
+   implied 
+   indirect-absolute 
+   absolute-indexed-x 
+   absolute-indexed-y 
+   zero-page-indexed-x 
+   zero-page-indexed-y 
+   indexed-indirect 
+   indirect-indexed 
+   relative 
+   accumulator))
+
+;;; Instructions, with decimal opcode and
+;;; addressing modes.
 (setf
  *instructions*
  ;; Load & Store
@@ -185,18 +202,15 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
    (NOP 234 (implied))
    (BRK   0 (implied))))
 
-;; Predicate: is a combination of instruction
-;; and addressing mode correct?
 (defun valid-instruction? (instruction addressing-mode)
-  (dolist (x *instructions* nil)
-	(when
-		(and
-		 (equal (car x) instruction)
-		 (member addressing-mode (caddr x)))
-	  (return T))))
+  "Is instruction and addressing mode combination correct?"
+  (cond
+	((member addressing-mode
+			 (caddr (assoc instruction *instructions*))) t)
+	(t nil)))
 
-;; Is string hexadecimal?
 (defun hexd? (string)
+  "Is a string a hexd number?"
   (let ((stack ()))
 	(dotimes (i (length string))
 	  (push
@@ -212,9 +226,8 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 	(push 'and stack)
 	(eval stack)))
 
-;; Convert an arbitrarily sized hexadecimal number as
-;; string, to a positive decimal integer.
 (defun hex2dec (string)
+  "Convert an arbitrarily sized hexd number (as string) to a positive decimal."
   (flet ((hex (c)
 		   (cond
 			 ((and (char-not-lessp c #\0)
@@ -236,10 +249,8 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 					(hex (char string i))))))
 	  ret)))
 
-;;(define-compiler-macro (list)
 ;; A list with with the respective rules of some
 ;; addressing mode syntax.
-;; ... ... ... could definitely macro most of them.
 (setf
  *addressing-modes-syntax*
  '((immediate ; #?? ... more complex syntax rules for later
@@ -321,8 +332,8 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 	   (equal (length s) 1)
 	   (equal "A" (subseq s 0 1)))))))
 
-;; EXAMPLE
 ;; Evaluate the second syntax rule on a string
+;; temporary
 (funcall
- (eval (cadar (cdr *addressing-modes-syntax*)))
+ (eval (cadr (assoc 'absolute *addressing-modes-syntax*)))
  "$A6AF")