Function: disassemble-offset

disassemble-offset is a byte-compiled function defined in byte-opt.el.gz.

Signature

(disassemble-offset BYTES)

Documentation

Don't call this!

Source Code

;; Defined in /usr/src/emacs/lisp/emacs-lisp/byte-opt.el.gz
;; This function extracts the bitfields from variable-length opcodes.
;; Originally defined in disass.el (which no longer uses it.)
(defun disassemble-offset (bytes)
  "Don't call this!"
  ;; Fetch and return the offset for the current opcode.
  ;; Return nil if this opcode has no offset.
  (cond ((< bytedecomp-op byte-pophandler)
	 (let ((tem (logand bytedecomp-op 7)))
	   (setq bytedecomp-op (logand bytedecomp-op 248))
	   (cond ((eq tem 6)
		  ;; Offset in next byte.
		  (setq bytedecomp-ptr (1+ bytedecomp-ptr))
		  (aref bytes bytedecomp-ptr))
		 ((eq tem 7)
		  ;; Offset in next 2 bytes.
		  (setq bytedecomp-ptr (1+ bytedecomp-ptr))
		  (+ (aref bytes bytedecomp-ptr)
		     (progn (setq bytedecomp-ptr (1+ bytedecomp-ptr))
			    (ash (aref bytes bytedecomp-ptr) 8))))
		 (t tem))))		;Offset was in opcode.
	((>= bytedecomp-op byte-constant)
	 (prog1 (- bytedecomp-op byte-constant)	;Offset in opcode.
	   (setq bytedecomp-op byte-constant)))
	((or (and (>= bytedecomp-op byte-constant2)
                  (<= bytedecomp-op byte-goto-if-not-nil-else-pop))
             (memq bytedecomp-op (eval-when-compile
                                   (list byte-stack-set2 byte-pushcatch
                                         byte-pushconditioncase))))
	 ;; Offset in next 2 bytes.
	 (setq bytedecomp-ptr (1+ bytedecomp-ptr))
	 (+ (aref bytes bytedecomp-ptr)
	    (progn (setq bytedecomp-ptr (1+ bytedecomp-ptr))
		   (ash (aref bytes bytedecomp-ptr) 8))))
	((and (>= bytedecomp-op byte-listN)
	      (<= bytedecomp-op byte-discardN))
	 (setq bytedecomp-ptr (1+ bytedecomp-ptr)) ;Offset in next byte.
	 (aref bytes bytedecomp-ptr))))