;;; asm-mode.el --- mode for editing assembler code

;;; Commentary:

;; This mode was written by Eric S. Raymond <esr@snark.thyrsus.com>,
;; inspired by an earlier asm-mode by Martin Neitzel.

;; This minor mode is based on text mode.  It defines a private abbrev table
;; that can be used to save abbrevs for assembler mnemonics.  It binds just
;; five keys:
;;
;;	TAB		tab to next tab stop
;;	:		outdent preceding label, tab to tab stop
;;	comment char	place or move comment
;;			asm-comment-char specifies which character this is;
;;			you can use a different character in different
;;			Asm mode buffers.
;;	C-j, C-m	newline and tab to tab stop
;;
;; Code is indented to the first tab stop level.

;; This mode runs two hooks:
;;   1) An asm-mode-set-comment-hook before the part of the initialization
;; depending on asm-comment-char, and
;;   2) an asm-mode-hook at the end of initialization.

;;; Code:

(defgroup asm nil
  "X16 Assembler programming"
  :group 'languages)


(defcustom asm-comment-char ?*
  "*The comment-start character assumed by Asm mode."
  :type 'sexp
  :group 'asm)

;; XEmacs change (This is the primary difference, why was this
;;  feature removed? -sb)
(defcustom asm-support-c-comments-p nil
  "*Support C style comments.  If t C style comments will be
supported.  This is mainly for the benefit of font-lock."
  :type 'boolean
  :group 'asm)

(defcustom asm-mode-syntax-table nil
  "Syntax table used while in Asm mode.")

(defvar asm-mode-abbrev-table nil
  "Abbrev table used while in Asm mode.")
(define-abbrev-table 'asm-mode-abbrev-table ())

(defvar asm-mode-map nil
  "Keymap for Asm mode.")

;;(if asm-mode-map
;;    nil
  ;; XEmacs change
  (setq asm-mode-map (make-sparse-keymap 'asm-mode-map))
  ;; Note that the comment character isn't set up until asm-mode is called.
  (define-key asm-mode-map ":"	'asm-colon)
  (define-key asm-mode-map "\C-h"       'asm-backspace)
  (define-key asm-mode-map "\C-l"       'asm-halfdelim)
  (define-key asm-mode-map "\M-l"       'asm-fulldelim)
  (define-key asm-mode-map "\C-i"       'asm-tabulator)
;;(define-key asm-mode-map "\C-a"	'asm-comment-region)
  (define-key asm-mode-map "\C-a"       'beginning-of-line)
  (define-key asm-mode-map "\C-j"	'asm-newline)
  (define-key asm-mode-map "\C-m"	'asm-newline)
;;  )

(defconst asm-font-lock-keywords
 '(("^\\(\\(\\sw\\|\\s_\\)+\\)\\>:?[ \t]*\\(\\sw+\\)?"
    (1 font-lock-function-name-face) (3 font-lock-keyword-face nil t))
   ("^\\s +\\(\\(\\sw\\|\\s_\\)+\\)" 1 font-lock-keyword-face))

 "Additional expressions to highlight in Assembler mode.")

;; XEmacs change
(put 'asm-mode 'font-lock-defaults '(asm-font-lock-keywords))
(defvar asm-code-level-empty-comment-pattern nil)
(defvar asm-flush-left-empty-comment-pattern nil)
(defvar asm-inline-empty-comment-pattern nil)


;;;###autoload
(defun asm-mode ()
  "Major mode for editing typical assembler code.
Features a private abbrev table and the following bindings:

\\[asm-colon]\toutdent a preceding label, tab to next tab stop.
\\[tab-to-tab-stop]\ttab to next tab stop.
\\[asm-newline]\tnewline, then tab to next tab stop.
\\[asm-comment]\tsmart placement of assembler comments.

The character used for making comments is set by the variable
`asm-comment-char' (which defaults to `?;').

Alternatively, you may set this variable in `asm-mode-set-comment-hook',
which is called near the beginning of mode initialization.

Turning on Asm mode runs the hook `asm-mode-hook' at the end of initialization.

Special commands:
\\{asm-mode-map}
"
  (interactive)

;;  (make-local-variable 'asm-comment-space)

  (setq asm-comment-space " ")

  (kill-all-local-variables)
  (setq mode-name "Assembler")
  (setq major-mode 'asm-mode)
  (setq local-abbrev-table asm-mode-abbrev-table)
  (make-local-variable 'font-lock-defaults)
  (setq font-lock-defaults '(asm-font-lock-keywords))
  (make-local-variable 'asm-mode-syntax-table)
  (setq asm-mode-syntax-table (make-syntax-table))
  (set-syntax-table asm-mode-syntax-table)

  (run-hooks 'asm-mode-set-comment-hook)
  ;; Make our own local child of asm-mode-map
  ;; so we can define our own comment character.
  ;; XEmacs change
  (let ((ourmap (make-sparse-keymap)))
    (set-keymap-parents ourmap (list asm-mode-map))
    (use-local-map ourmap))
  (local-set-key (vector asm-comment-char) 'asm-comment)
  ;; XEmacs change


  (if asm-support-c-comments-p
      (progn
	(modify-syntax-entry ?/ ". 14" asm-mode-syntax-table)
	(modify-syntax-entry ?* ". 23" asm-mode-syntax-table)
	(modify-syntax-entry asm-comment-char "< b" asm-mode-syntax-table)
	(modify-syntax-entry ?\n "> b" asm-mode-syntax-table))
    (progn
      (modify-syntax-entry asm-comment-char
			   "<" asm-mode-syntax-table)
      (modify-syntax-entry ?\n
			   ">" asm-mode-syntax-table)))


  (let ((cs (regexp-quote (char-to-string asm-comment-char))))
    (make-local-variable 'comment-start)
    (setq comment-start (concat cs asm-comment-space))
    (make-local-variable 'comment-start-skip)
    (setq comment-start-skip (concat cs "+[ \t]*"))
    (setq asm-inline-empty-comment-pattern (concat "^.+" cs "+ *$"))
    (setq asm-code-level-empty-comment-pattern (concat "^[\t ]+" cs cs " *$"))
    (setq asm-flush-left-empty-comment-pattern (concat "^" cs cs cs " *$"))
    )
  (make-local-variable 'comment-end)
  (setq comment-end "")
  (make-local-variable 'comment-column)
  (setq comment-column 32)
  (setq fill-prefix "\t")
  (run-hooks 'asm-mode-hook))

(defun asm-colon ()
  "Insert a colon; if it follows a label, delete the label's indentation."
  (interactive)
  (if (is-comment-line) (progn (asm-comment-line) (tab-to-tab-stop))
    (cond
     
      ;; unindent input
      ( (save-excursion (beginning-of-line) (looking-at "\**[ \t]+\\(\\sw\\|\\s_\\)+$"))
         (save-excursion (beginning-of-line) (delete-horizontal-space))
	 (tab-to-tab-stop)
	 )
      
      (t 
       (insert ":")
      )
   )
  ))

(defun asm-line-matches (pattern &optional withcomment)
  (save-excursion
    (beginning-of-line)
    (looking-at pattern)))

(defun asm-pop-comment-level ()
  ;; Delete an empty comment ending current line.  Then set up for a new one,
  ;; on the current line if it was all comment, otherwise above it
  (end-of-line)
  (delete-horizontal-space)
  (while (= (preceding-char) asm-comment-char)
    (delete-backward-char 1))
  (delete-horizontal-space)
  (if (bolp)
      nil
    (beginning-of-line)
    (open-line 1))
  )


(defun asm-comment ()
  "Convert an empty comment to a `larger' kind, or start a new one.
These are the known comment classes:

   1 -- comment to the right of the code (at the comment-column)
   2 -- comment on its own line, indented like code
   3 -- comment on its own line, beginning at the left-most column.

Suggested usage:  while writing your code, trigger asm-comment
repeatedly until you are satisfied with the kind of comment."
  (interactive)
 
 (setq comment-start "")

  (cond

   ;; Blank line?  Then start comment.
   ((asm-line-matches "^[ \t]*$")
    (delete-horizontal-space)
;;    (insert asm-comment-char comment-start)
    (insert asm-comment-char asm-comment-space) 
    )

   ;; Nonblank line with no comment chars in it?
   ;; Then start a comment at the current comment column
   ;;( (if (is-comment-line) nil t)
   ;; (indent-for-comment)  
;;)

   ;; Flush-left comment present?  Just insert character.
;;   ((asm-line-matches asm-flush-left-empty-comment-pattern)
;;    (insert asm-comment-char))

   ;; Fresh comment line??
   ( (asm-line-matches (format "^%c%s$" asm-comment-char asm-comment-space))
    (end-of-line)
    (delete-backward-char (length asm-comment-space))
    (insert asm-comment-char asm-comment-char)
   )

   
   ;; Empty code-level comment already present?
   ;; Then start flush-left comment, on line above if this one is nonempty. 
;;   ((asm-line-matches asm-code-level-empty-comment-pattern)
;;    (asm-pop-comment-level)
;;    (insert asm-comment-char asm-comment-char comment-start))

   ;; Empty comment ends line?
   ;; Then make code-level comment, on line above if this one is nonempty. 
;;   ((asm-line-matches asm-inline-empty-comment-pattern)
;;    (asm-pop-comment-level)
;;    (tab-to-tab-stop)
;;    (insert asm-comment-char comment-start))

   ;; If all else fails, insert character
   (t
    (insert asm-comment-char))

   )
  (end-of-line))

;; ****************************************************************************


(defun pos-in-line ()
  (- (point) (save-excursion (beginning-of-line) (point))))


(defun at-begin-of-line ()
  (interactive)
    (setq pos (point) )
(save-excursion  
  (beginning-of-line)
    (if (= pos (point)) t nil)
    )
)

(defun is-comment-line ()
  (if (asm-line-matches (format "^%c" asm-comment-char))
    t
    nil)
)

(defun in-comment-spacing ()
 (if (> (current-column) (length (format "%c%s" asm-comment-char asm-comment-space))) nil t)
)

(defun asm-comment-line()
 (interactive)
 (if (is-comment-line) 
     (save-excursion 
       (beginning-of-line) 
       (delete-char 1)
       (if (looking-at "^ ")
	   (delete-char 1)
	 )
     )
     (save-excursion (beginning-of-line) (insert asm-comment-char asm-comment-space)) 
  )
)

(defun line-start()
  (save-excursion
    (beginning-of-line)
    (point)
    )
)

(defun asm-comment-region()
 (interactive)
 
 (if (not (region-active-p)) (asm-comment-line)
   (save-excursion 
     (goto-char (region-end))
     (setq lastline (line-number))
     (goto-char (region-beginning))
     (while (< (line-number) lastline)
       (asm-comment-line)
       (next-line 1)
       ))))
    
   
(defun asm-backspace ()
  (interactive)
  (if (and (is-comment-line) (in-comment-spacing))
      (delete-region (- (line-start) 1) (point))
     (delete-backward-char 1)
  )
;;delete-backward-char (length (format "%c%s" asm-comment-char asm-comment-space))) (tab-to-tab-stop))
;; (delete-backward-char 1)
  )

(defun asm-fulldelim ()
  (interactive)
  (make-local-variable 'count)
  (setq count 0)
  (if (asm-line-matches (format "^%c%s$" asm-comment-char asm-comment-space)) 
       (progn (setq count 1)
       (end-of-line)
       (delete-backward-char (length asm-comment-space)))
  )
  
  (while (< count 80) 
    (insert asm-comment-char) 
    (setq count ( 1+ count)))
)


(defun asm-halfdelim ()
  (interactive)
  (make-local-variable 'count)
  (setq count 0)
  (if (asm-line-matches (format "^%c%s$" asm-comment-char asm-comment-space)) 
       (progn (setq count 1)
       (end-of-line)
       (delete-backward-char (length asm-comment-space)))
  )
  
  (while (< count 40) 
    (insert asm-comment-char) 
    (setq count ( 1+ count)))

)


(defun asm-tabulator ()
  (interactive)
  (if (is-comment-line)
      (progn
	(setq target (prog2 (insert "\t") (current-column) (delete-backward-char 1)  ))
	     (while (< (current-column) target) (insert " "))
        )
      
       (tab-to-tab-stop)
     )
)


(defun asm-newline ()
  "Insert LFD + fill-prefix, to bring us back to code-indent level."
  (interactive)
  
  (if (is-comment-line)
     (progn
       (if (at-begin-of-line) (goto-char (+ (point) 1)))
       (insert "\n" asm-comment-char asm-comment-space))

     (if (eolp) 
	 (progn (delete-horizontal-space)
                (insert "\n")  
		(tab-to-tab-stop)
	  )
      (insert "\n")  
     
     )
     )
)
  

;; XEmacs addition
;;;###autoload(add-to-list 'auto-mode-alist '("\\.[sS]\\'" . asm-mode))
;;;###autoload(add-to-list 'auto-mode-alist '("\\.asm\\'" . asm-mode))

;;; asm-mode.el ends here