cairo/src/cairo-base85-stream.c

   1 /* -*- Mode: c; c-basic-offset: 4; indent-tabs-mode: t; tab-width: 8; -*- */
   2 /* cairo - a vector graphics library with display and print output
   3  *
   4  * Copyright © 2005 Red Hat, Inc
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it either under the terms of the GNU Lesser General Public
   8  * License version 2.1 as published by the Free Software Foundation
   9  * (the "LGPL") or, at your option, under the terms of the Mozilla
  10  * Public License Version 1.1 (the "MPL"). If you do not alter this
  11  * notice, a recipient may use your version of this file under either
  12  * the MPL or the LGPL.
  13  *
  14  * You should have received a copy of the LGPL along with this library
  15  * in the file COPYING-LGPL-2.1; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  17  * You should have received a copy of the MPL along with this library
  18  * in the file COPYING-MPL-1.1
  19  *
  20  * The contents of this file are subject to the Mozilla Public License
  21  * Version 1.1 (the "License"); you may not use this file except in
  22  * compliance with the License. You may obtain a copy of the License at
  23  * http://www.mozilla.org/MPL/
  24  *
  25  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
  26  * OF ANY KIND, either express or implied. See the LGPL or the MPL for
  27  * the specific language governing rights and limitations.
  28  *
  29  * The Original Code is the cairo graphics library.
  30  *
  31  * The Initial Developer of the Original Code is Red Hat, Inc.
  32  *
  33  * Author(s):
  34  *      Kristian Høgsberg <krh@redhat.com>
  35  */
  36
  37 #include "cairoint.h"
  38 #include "cairo-output-stream-private.h"
  39
  40 typedef struct _cairo_base85_stream {
  41     cairo_output_stream_t base;
  42     cairo_output_stream_t *output;
  43     unsigned char four_tuple[4];
  44     int pending;
  45 } cairo_base85_stream_t;
  46
  47 static void
  48 _expand_four_tuple_to_five (unsigned char four_tuple[4],
  49                             unsigned char five_tuple[5],
  50                             cairo_bool_t *all_zero)
  51 {
  52     uint32_t value;
  53     int digit, i;
  54
  55     value = four_tuple[0] << 24 | four_tuple[1] << 16 | four_tuple[2] << 8 | four_tuple[3];
  56     if (all_zero)
  57         *all_zero = TRUE;
  58     for (i = 0; i < 5; i++) {
  59         digit = value % 85;
  60         if (digit != 0 && all_zero)
  61             *all_zero = FALSE;
  62         five_tuple[4-i] = digit + 33;
  63         value = value / 85;
  64     }
  65 }
  66
  67 static cairo_status_t
  68 _cairo_base85_stream_write (cairo_output_stream_t *base,
  69                             const unsigned char   *data,
  70                             unsigned int           length)
  71 {
  72     cairo_base85_stream_t *stream = (cairo_base85_stream_t *) base;
  73     const unsigned char *ptr = data;
  74     unsigned char five_tuple[5];
  75     cairo_bool_t is_zero;
  76
  77     while (length) {
  78         stream->four_tuple[stream->pending++] = *ptr++;
  79         length--;
  80         if (stream->pending == 4) {
  81             _expand_four_tuple_to_five (stream->four_tuple, five_tuple, &is_zero);
  82             if (is_zero)
  83                 _cairo_output_stream_write (stream->output, "z", 1);
  84             else
  85                 _cairo_output_stream_write (stream->output, five_tuple, 5);
  86             stream->pending = 0;
  87         }
  88     }
  89
  90     return _cairo_output_stream_get_status (stream->output);
  91 }
  92
  93 static cairo_status_t
  94 _cairo_base85_stream_close (cairo_output_stream_t *base)
  95 {
  96     cairo_base85_stream_t *stream = (cairo_base85_stream_t *) base;
  97     unsigned char five_tuple[5];
  98
  99     if (stream->pending) {
 100         memset (stream->four_tuple + stream->pending, 0, 4 - stream->pending);
 101         _expand_four_tuple_to_five (stream->four_tuple, five_tuple, NULL);
 102         _cairo_output_stream_write (stream->output, five_tuple, stream->pending + 1);
 103     }
 104
 105     /* Mark end of base85 data */
 106     _cairo_output_stream_printf (stream->output, "~>");
 107
 108     return _cairo_output_stream_get_status (stream->output);
 109 }
 110
 111 cairo_output_stream_t *
 112 _cairo_base85_stream_create (cairo_output_stream_t *output)
 113 {
 114     cairo_base85_stream_t *stream;
 115
 116     if (output->status)
 117         return _cairo_output_stream_create_in_error (output->status);
 118
 119     stream = malloc (sizeof (cairo_base85_stream_t));
 120     if (stream == NULL) {
 121         _cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
 122         return (cairo_output_stream_t *) &_cairo_output_stream_nil;
 123     }
 124
 125     _cairo_output_stream_init (&stream->base,
 126                                _cairo_base85_stream_write,
 127                                _cairo_base85_stream_close);
 128     stream->output = output;
 129     stream->pending = 0;
 130
 131     return &stream->base;
 132 }