;;;; -*- Mode: Lisp; Syntax: ANSI-Common-Lisp; Base: 10 -*-
;;;; *************************************************************************
;;;; FILE IDENTIFICATION
;;;;
;;;; Name:          compress.cl
;;;; Purpose:       UFFI Example file for zlib compression
;;;; Programmer:    Kevin M. Rosenberg
;;;; Date Started:  Feb 2002
;;;;
;;;; $Id: compress.lisp,v 1.2 2002/12/03 06:58:39 kevin Exp $
;;;;
;;;; This file, part of UFFI, is Copyright (c) 2002 by Kevin M. Rosenberg
;;;;
;;;; UFFI users are granted the rights to distribute and use this software
;;;; as governed by the terms of the Lisp Lesser GNU Public License
;;;; (http://opensource.franz.com/preamble.html), also known as the LLGPL.
;;;; *************************************************************************

(in-package :cl-user)

(eval-when (:load-toplevel :execute)
  (unless (uffi:load-foreign-library
	   #-(or macosx darwin)
	   (uffi:find-foreign-library
	    "libz"
	    '("/usr/local/lib/" "/usr/lib/" "/zlib/")
	    :types '("so" "a"))
	   #+(or macosx darwin)
	   (uffi:find-foreign-library "z"
				      `(,(pathname-directory *load-pathname*)))
	   :module "zlib" 
	   :supporting-libraries '("c"))
    (warn "Unable to load zlib")))
  
(uffi:def-function ("compress" c-compress)
    ((dest (* :unsigned-char))
     (destlen (* :long))
     (source :cstring)
     (source-len :long))
  :returning :int
  :module "zlib")
  
(defun compress (source)
  "Returns two values: array of bytes containing the compressed data
 and the numbe of compressed bytes"
  (let* ((sourcelen (length source))
	 (destsize (+ 12 (ceiling (* sourcelen 1.01))))
	 (dest (uffi:allocate-foreign-string destsize :unsigned t))
	 (destlen (uffi:allocate-foreign-object :long)))
    (setf (uffi:deref-pointer destlen :long) destsize)
    (uffi:with-cstring (source-native source)
      (let ((result (c-compress dest destlen source-native sourcelen))
	    (newdestlen (uffi:deref-pointer destlen :long)))
	(unwind-protect
	    (if (zerop result)
		(values (uffi:convert-from-foreign-string 
			 dest
			 :length newdestlen
			 :null-terminated-p nil)
			newdestlen)
	      (error "zlib error, code ~D" result))
	  (progn
	    (uffi:free-foreign-object destlen)
	    (uffi:free-foreign-object dest)))))))


#+examples-uffi
(progn
  (flet ((print-results (str)
	   (multiple-value-bind (compressed len) (compress str)
	       (format t "~&(compress ~S) => " str)
	       (dotimes (i len)
		 (format t "~X" (char-code (char compressed i))))
	       (format t ",~D" len))))
    (print-results "")
    (print-results "test")
    (print-results "test2")))

;; Results of the above on my system:
;; (compress "") => 789c300001,8
;; (compress "test") => 789c2b492d2e1045d1c1,12
;; (compress "test2") => 789c2b492d2e31206501f3,13