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  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., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, 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-error-private.h"
  39. #include "cairo-output-stream-private.h"
  40.  
  41. typedef struct _cairo_base85_stream {
  42.     cairo_output_stream_t base;
  43.     cairo_output_stream_t *output;
  44.     unsigned char four_tuple[4];
  45.     int pending;
  46. } cairo_base85_stream_t;
  47.  
  48. static void
  49. _expand_four_tuple_to_five (unsigned char four_tuple[4],
  50.                             unsigned char five_tuple[5],
  51.                             cairo_bool_t *all_zero)
  52. {
  53.     uint32_t value;
  54.     int digit, i;
  55.  
  56.     value = four_tuple[0] << 24 | four_tuple[1] << 16 | four_tuple[2] << 8 | four_tuple[3];
  57.     if (all_zero)
  58.         *all_zero = TRUE;
  59.     for (i = 0; i < 5; i++) {
  60.         digit = value % 85;
  61.         if (digit != 0 && all_zero)
  62.             *all_zero = FALSE;
  63.         five_tuple[4-i] = digit + 33;
  64.         value = value / 85;
  65.     }
  66. }
  67.  
  68. static cairo_status_t
  69. _cairo_base85_stream_write (cairo_output_stream_t *base,
  70.                             const unsigned char   *data,
  71.                             unsigned int           length)
  72. {
  73.     cairo_base85_stream_t *stream = (cairo_base85_stream_t *) base;
  74.     const unsigned char *ptr = data;
  75.     unsigned char five_tuple[5];
  76.     cairo_bool_t is_zero;
  77.  
  78.     while (length) {
  79.         stream->four_tuple[stream->pending++] = *ptr++;
  80.         length--;
  81.         if (stream->pending == 4) {
  82.             _expand_four_tuple_to_five (stream->four_tuple, five_tuple, &is_zero);
  83.             if (is_zero)
  84.                 _cairo_output_stream_write (stream->output, "z", 1);
  85.             else
  86.                 _cairo_output_stream_write (stream->output, five_tuple, 5);
  87.             stream->pending = 0;
  88.         }
  89.     }
  90.  
  91.     return _cairo_output_stream_get_status (stream->output);
  92. }
  93.  
  94. static cairo_status_t
  95. _cairo_base85_stream_close (cairo_output_stream_t *base)
  96. {
  97.     cairo_base85_stream_t *stream = (cairo_base85_stream_t *) base;
  98.     unsigned char five_tuple[5];
  99.  
  100.     if (stream->pending) {
  101.         memset (stream->four_tuple + stream->pending, 0, 4 - stream->pending);
  102.         _expand_four_tuple_to_five (stream->four_tuple, five_tuple, NULL);
  103.         _cairo_output_stream_write (stream->output, five_tuple, stream->pending + 1);
  104.     }
  105.  
  106.     return _cairo_output_stream_get_status (stream->output);
  107. }
  108.  
  109. cairo_output_stream_t *
  110. _cairo_base85_stream_create (cairo_output_stream_t *output)
  111. {
  112.     cairo_base85_stream_t *stream;
  113.  
  114.     if (output->status)
  115.         return _cairo_output_stream_create_in_error (output->status);
  116.  
  117.     stream = malloc (sizeof (cairo_base85_stream_t));
  118.     if (unlikely (stream == NULL)) {
  119.         _cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
  120.         return (cairo_output_stream_t *) &_cairo_output_stream_nil;
  121.     }
  122.  
  123.     _cairo_output_stream_init (&stream->base,
  124.                                _cairo_base85_stream_write,
  125.                                NULL,
  126.                                _cairo_base85_stream_close);
  127.     stream->output = output;
  128.     stream->pending = 0;
  129.  
  130.     return &stream->base;
  131. }
  132.