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;; -*- mode: common-lisp -*-
#|
clasm-6502: An assembler for the 6502 written in Common Lisp.
Copyright (C) 2024 Aleksei Eaves
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
|#
;; Rules for the interpretation of lines.
(defparameter
*line-syntax*
'(
(label
(lambda (l)
(and (eq (last-char (first l)) #\:)
(eq (length l) 1))))
(label-instruction
(lambda (l)
(and (eq (last-char (first l)) #\:)
(member (read-from-string (second l)) *opcodes*))))
(attribute
(lambda (l)
(equal (char (first l) 0) #\.)))
(instruction
(lambda (l)
(member (read-from-string (first l)) *opcodes*)))
(macro
(lambda (l)
(equal (second l) "=")))
(unknown
(lambda (l)
t))))
;; Rules for identifying addressing modes.
(defparameter
*addressing-modes-syntax*
'((immediate ; #?? ... more complex syntax rules for later
(lambda (s)
(eq "#" (subseq s 0 1))))
(absolute ;"$????"
(lambda (s)
(and
(equal (length s) 5)
(equal "$" (subseq s 0 1))
(hexd? (subseq s 1 5)))))
(zero-page ;"$??"
(lambda (s)
(and
(equal (length s) 3)
(equal "$" (subseq s 0 1))
(hexd? (subseq s 1 3)))))
(implied nil)
(indirect-absolute ;($????)
(lambda (s)
(and
(equal (length s) 7)
(equal "($" (subseq s 0 2))
(hexd? (subseq s 1 5))
(equal ")" (subseq s 5 6)))))
(absolute-indexed-x ;"$????,X"
(lambda (s)
(and
(equal (length s) 7)
(equal "$" (subseq s 0 1))
(hexd? (subseq s 1 5))
(equal ",X" (subseq s 5 7)))))
(absolute-indexed-y ;"$????,Y"
(lambda (s)
(and
(equal (length s) 7)
(equal "$" (subseq s 0 1))
(hexd? (subseq s 1 5))
(equal ",Y" (subseq s 5 7)))))
(zero-page-indexed-x ;"$??,X"
(lambda (s)
(and
(equal (length s) 5)
(equal (subseq s 0 1) "$")
(hexd? (subseq s 1 3))
(equal (subseq s 3 5) ",X"))))
(zero-page-indexed-y ;"$??,Y"
(lambda (s)
(and
(equal (length s) 5)
(equal (subseq s 0 1) "$")
(hexd? (subseq s 1 3))
(equal (subseq s 3 5) ",Y"))))
(indexed-indirect ;"($??,X)"
(lambda (s)
(and
(equal (length s) 7)
(equal (subseq s 0 2) "($")
(hexd? (subseq s 2 4))
(equal (subseq s 4 7) ",X)"))))
(indirect-indexed ;"($??),Y"
(lambda (s)
(and
(equal (length s) 7)
(equal (subseq s 0 2) "($")
(hexd? (subseq s 2 4))
(equal (subseq s 4 7) "),Y"))))
;;How to fix that relative and absolute are the same rule?
;;A check upstream would suffice.
(relative ;"$????"
(lambda (s)
(and
(equal (length s) 5)
(equal (subseq s 0 1) "$")
(hexd? (subseq s 1 5)))))
(accumulator ;"A"
(lambda (s)
(and
(equal (length s) 1)
(equal "A" (subseq s 0 1)))))))
(defun syntax-rule (line list)
"Apply a syntax rule against a delimited line from a program."
(dolist (i (extract-keys list))
(let ((z (funcall (eval (cadr (assoc i list)))
line)))
(if (not (equal
z nil))
(return i)
nil))))
|
