source: trunk/abcl/src/org/armedbear/lisp/byte-io.lisp @ 11457

Last change on this file since 11457 was 11391, checked in by vvoutilainen, 13 years ago

ABCL license is GPL + Classpath exception. This was intended
by Peter Graves, the original author. For reference, see

  • Property svn:eol-style set to native
  • Property svn:keywords set to Id
File size: 3.2 KB
1;;; byte-io.lisp
3;;; Copyright (C) 2004-2005 Peter Graves
4;;; $Id: byte-io.lisp 11391 2008-11-15 22:38:34Z vvoutilainen $
6;;; This program is free software; you can redistribute it and/or
7;;; modify it under the terms of the GNU General Public License
8;;; as published by the Free Software Foundation; either version 2
9;;; of the License, or (at your option) any later version.
11;;; This program is distributed in the hope that it will be useful,
12;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
14;;; GNU General Public License for more details.
16;;; You should have received a copy of the GNU General Public License
17;;; along with this program; if not, write to the Free Software
18;;; Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
20;;; As a special exception, the copyright holders of this library give you
21;;; permission to link this library with independent modules to produce an
22;;; executable, regardless of the license terms of these independent
23;;; modules, and to copy and distribute the resulting executable under
24;;; terms of your choice, provided that you also meet, for each linked
25;;; independent module, the terms and conditions of the license of that
26;;; module.  An independent module is a module which is not derived from
27;;; or based on this library.  If you modify this library, you may extend
28;;; this exception to your version of the library, but you are not
29;;; obligated to do so.  If you do not wish to do so, delete this
30;;; exception statement from your version.
32(in-package #:system)
34(defun write-byte (byte stream)
35  (declare (type stream stream))
36  (let ((element-type (stream-element-type stream)))
37    (require-type byte element-type)
38    (let ((width (cadr element-type)))
39      (if (= width 8)
40          (write-8-bits (the (unsigned-byte 8) byte) stream)
41          (let ((bytes ()))
42            (dotimes (i (/ width 8))
43              (push (logand byte #xff) bytes)
44              (setf byte (ash byte -8)))
45            (dolist (b bytes)
46              (write-8-bits (the (unsigned-byte 8) b) stream)))))
47    byte))
49(defun read-byte (stream &optional (eof-error-p t) eof-value)
50  (declare (type stream stream))
51  (let* ((element-type (stream-element-type stream)))
52    (unless element-type
53      (if eof-error-p
54          (error 'end-of-file :stream stream)
55          (return-from read-byte eof-value)))
56    (unless (consp element-type)
57      (error 'simple-type-error
58             :format-control "READ-BYTE: unsupported element type ~S."
59             :format-arguments (list element-type)))
60    (let ((width (cadr element-type)))
61      (if (= width 8)
62          (read-8-bits stream eof-error-p eof-value)
63          (let ((result 0))
64            (dotimes (i (/ width 8))
65              (let ((byte (read-8-bits stream eof-error-p eof-value)))
66                (when (eq byte eof-value)
67                  (return-from read-byte eof-value))
68                (setf result (ash result 8))
69                (setf result (+ result byte))))
70            (if (and (eq (car element-type) 'signed-byte)
71                     (not (zerop (logand result (expt 2 (1- width))))))
72                (- result (expt 2 width))
73                result))))))
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