diff options
Diffstat (limited to '6502.lisp')
| -rw-r--r-- | 6502.lisp | 45 |
1 files changed, 28 insertions, 17 deletions
@@ -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") |