;;; -*- Log: code.log; Package: Lisp -*-
;;;
;;; **********************************************************************
;;; This code was written as part of the CMU Common Lisp project at
;;; Carnegie Mellon University, and has been placed in the public domain.
;;;
(ext:file-comment
  "$Header: /home/pvaneynd/fakeroot/cvs2.cons.org/src/code/purify.lisp,v 1.18 1994/10/31 04:11:27 ram Exp $")
;;;
;;; **********************************************************************
;;;
;;; Storage purifier for Spice Lisp.
;;; Written by Rob MacLachlan and Skef Wholey.
;;;
;;; Rewritten in C by William Lott.
;;;
(in-package "LISP")
(export 'ext::purify "EXT")

(alien:def-alien-routine ("purify" %purify) c-call:void
  (static-roots c-call:unsigned-long)
  (read-only-roots c-call:unsigned-long))


;;; COMPACT-ENVIRONMENT-AUX  --  Internal
;;;
;;;    Compact the info environment.  Written with gratuitous recursion to
;;; make sure that our (and compact-info-environment's) local variables are
;;; above the stack top when purify runs.
;;;
(defun compact-environment-aux (name n)
  (cond
   ((zerop n)
    (let ((old-ie (car *info-environment*)))
      (setq *info-environment*
	    (list* (make-info-environment :name "Working")
		   (compact-info-environment (first *info-environment*)
					     :name name)
		   (rest *info-environment*)))
      (shrink-vector (c::volatile-info-env-table old-ie) 0)))
   (t
    (compact-environment-aux name (1- n))
    n)))


(defun purify (&key root-structures (environment-name "Auxiliary"))
  "This function optimizes garbage collection by moving all currently live
   objects into non-collected storage.  ROOT-STRUCTURES is an optional list of
   objects which should be copied first to maximize locality.

   DEFSTRUCT structures defined with the (:PURE T) option are moved into
   read-only storage, further reducing GC cost.  List and vector slots of pure
   structures are also moved into read-only storage.

   ENVIRONMENT-NAME is gratuitous documentation for compacted version of the
   current global environment (as seen in C::*INFO-ENVIRONMENT*.)  If NIL is
   supplied, then environment compaction is inhibited."

  (when environment-name (compact-environment-aux environment-name 200))

  (let ((*gc-notify-before*
	 #'(lambda (bytes-in-use)
	     (declare (ignore bytes-in-use))
	     (write-string "[Doing purification: ")
	     (force-output)))
	(*internal-gc*
	 #'(lambda ()
	     (%purify (get-lisp-obj-address root-structures)
		      (get-lisp-obj-address nil))))
	(*gc-notify-after*
	 #'(lambda (&rest ignore)
	     (declare (ignore ignore))
	     (write-line "Done.]"))))
    (gc t))
  nil)
