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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
|#
;; Every instruction, its decimal opcode, and the
;; usable addressing modes.
(setf
*instructions*
;; Load & Store
'((LDA 169 (immediate
absolute
zero-page
absolute-indexed-x
absolute-indexed-y
zero-page-indexed-x
indexed-indirect
indirect-indexed))
(LDX 162 (immediate
zero-page
zero-page-indexed-y
absolute
absolute-indexed-y))
(LDY 160 (immediate
zero-page
zero-page-indexed-x
absolute
absolute-indexed-x))
(STA 137 (absolute
zero-page
absolute-indexed-x
absolute-indexed-y
zero-page-indexed-x
indexed-indirect
indirect-indexed))
(STX 130 (zero-page
zero-page-indexed-y
absolute))
(STY 128 (zero-page
zero-page-indexed-x
absolute))
;;Arithmetic
(ADC 105 (immediate
absolute
zero-page
absolute-indexed-x
absolute-indexed-y
zero-page-indexed-x
indexed-indirect
indirect-indexed))
(SBC 233 (immediate
absolute
zero-page
absolute-indexed-x
absolute-indexed-y
zero-page-indexed-x
indexed-indirect
indirect-indexed))
;;Increment & Decrement
(INC 226 (zero-page
zero-page-indexed-x
absolute
absolute-indexed-x))
(INX 232 (implied))
(INY 200 (implied))
(DEC 194 (zero-page
zero-page-indexed-x
absolute
absolute-indexed-x))
(DEX 202 (implied))
(DEY 136 (implied))
;; Logical
(AND 41 (immediate
absolute
zero-page
absolute-indexed-x
absolute-indexed-y
zero-page-indexed-x
indexed-indirect
indirect-indexed))
(ORA 9 (immediate
absolute
zero-page
absolute-indexed-x
absolute-indexed-y
zero-page-indexed-x
indexed-indirect
indirect-indexed))
(EOR 73 (immediate
absolute
zero-page
absolute-indexed-x
absolute-indexed-y
zero-page-indexed-x
indexed-indirect
indirect-indexed))
;; Jump, Branch, Compare
(JMP 72 (absolute
indirect-absolute))
(BCC 144 (relative))
(BCS 176 (relative))
(BEQ 240 (relative))
(BNE 208 (relative))
(BMI 48 (relative))
(BPL 16 (relative))
(BVS 112 (relative))
(BVC 80 (relative))
(CMP 201 (immediate
absolute
zero-page
absolute-indexed-x
absolute-indexed-y
zero-page-indexed-x
indexed-indirect
indirect-indexed))
(CPX 224 (immediate
zero-page
absolute))
(CPY 192 (immediate
zero-page
absolute))
(BIT 32 (zero-page
absolute))
;; Shift & Rotate
(ASL 10 (accumulator
zero-page
zero-page-indexed-x
absolute
absolute-indexed-x))
(LSR 74 (accumulator
zero-page
zero-page-indexed-x
absolute
absolute-indexed-x))
(ROL 42 (accumulator
zero-page
zero-page-indexed-x
absolute
absolute-indexed-x))
(ROR 106 (accumulator
zero-page
zero-page-indexed-x
absolute
absolute-indexed-x))
;; Transfer
(TAX 170 (implied))
(TAY 168 (implied))
(TXA 138 (implied))
(TYA 152 (implied))
;; Stack
(TSX 186 (implied))
(TXS 154 (implied))
(PHA 72 (implied))
(PHP 8 (implied))
(PLA 104 (implied))
(PLP 40 (implied))
;; Subroutine
(JSR 32 (implied))
(RTI 64 (implied))
(RTS 96 (implied))
;; Set & Reset
(CLC 24 (implied))
(CLD 216 (implied))
(CLI 88 (implied))
(CLV 184 (implied))
(SEC 56 (implied))
(SED 248 (implied))
(SEI 120 (implied))
;; Other
(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 string hexadecimal?
(defun hexd? (string)
(let ((stack ()))
(dotimes (i (length string))
(push
(or (and (char-not-lessp
(char string i) #\0)
(char-not-greaterp
(char string i) #\9))
(and (char-not-lessp
(char string i) #\A)
(char-not-greaterp
(char string i) #\F)))
stack))
(push 'and stack)
(eval stack)))
;; Convert an arbitrarily sized hexadecimal number as
;; string, to a positive decimal integer.
(defun hex2dec (string)
(flet ((hex (c)
(cond
((and (char-not-lessp c #\0)
(char-not-greaterp c #\9))
(- (char-code c)
(char-code #\0)))
((and (char-not-lessp c #\A)
(char-not-greaterp c #\F))
(+ (- (char-code (char-downcase c))
(char-code #\a))
10)))))
(let ((ret 0))
(do ((i 0 (incf i))
(j (- (length string) 1) (decf j)))
((minusp j) ())
(setf ret
(+ ret
(* (expt 16 j)
(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
(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)))))))
;; EXAMPLE
;; Evaluate the second syntax rule on a string
(funcall
(eval (cadar (cdr *addressing-modes-syntax*)))
"$A6AF")
|
