1// Copyright 2014 PDFium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
6// Original code is licensed as follows:
7/*
8 * Copyright 2007 ZXing authors
9 *
10 * Licensed under the Apache License, Version 2.0 (the "License");
11 * you may not use this file except in compliance with the License.
12 * You may obtain a copy of the License at
13 *
14 *      http://www.apache.org/licenses/LICENSE-2.0
15 *
16 * Unless required by applicable law or agreed to in writing, software
17 * distributed under the License is distributed on an "AS IS" BASIS,
18 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
19 * See the License for the specific language governing permissions and
20 * limitations under the License.
21 */
22
23#include "fxbarcode/common/reedsolomon/BC_ReedSolomon.h"
24
25#include <memory>
26#include <utility>
27
28#include "fxbarcode/common/reedsolomon/BC_ReedSolomonGF256.h"
29#include "fxbarcode/common/reedsolomon/BC_ReedSolomonGF256Poly.h"
30#include "third_party/base/ptr_util.h"
31
32CBC_ReedSolomonEncoder::CBC_ReedSolomonEncoder(CBC_ReedSolomonGF256* field)
33    : m_field(field) {}
34
35CBC_ReedSolomonEncoder::~CBC_ReedSolomonEncoder() {}
36
37void CBC_ReedSolomonEncoder::Init() {
38  m_cachedGenerators.push_back(
39      pdfium::MakeUnique<CBC_ReedSolomonGF256Poly>(m_field.Get(), 1));
40}
41
42CBC_ReedSolomonGF256Poly* CBC_ReedSolomonEncoder::BuildGenerator(
43    size_t degree) {
44  if (degree >= m_cachedGenerators.size()) {
45    CBC_ReedSolomonGF256Poly* lastGenerator = m_cachedGenerators.back().get();
46    for (size_t d = m_cachedGenerators.size(); d <= degree; ++d) {
47      std::vector<int32_t> temp = {1, m_field->Exp(d - 1)};
48      CBC_ReedSolomonGF256Poly temp_poly;
49      if (!temp_poly.Init(m_field.Get(), &temp))
50        return nullptr;
51
52      auto nextGenerator = lastGenerator->Multiply(&temp_poly);
53      if (!nextGenerator)
54        return nullptr;
55
56      lastGenerator = nextGenerator.get();
57      m_cachedGenerators.push_back(std::move(nextGenerator));
58    }
59  }
60  return m_cachedGenerators[degree].get();
61}
62
63bool CBC_ReedSolomonEncoder::Encode(std::vector<int32_t>* toEncode,
64                                    size_t ecBytes) {
65  if (ecBytes == 0)
66    return false;
67
68  if (toEncode->size() <= ecBytes)
69    return false;
70
71  CBC_ReedSolomonGF256Poly* generator = BuildGenerator(ecBytes);
72  if (!generator)
73    return false;
74
75  size_t dataBytes = toEncode->size() - ecBytes;
76  std::vector<int32_t> infoCoefficients(dataBytes);
77  for (size_t x = 0; x < dataBytes; x++)
78    infoCoefficients[x] = (*toEncode)[x];
79
80  CBC_ReedSolomonGF256Poly info;
81  if (!info.Init(m_field.Get(), &infoCoefficients))
82    return false;
83
84  auto infoTemp = info.MultiplyByMonomial(ecBytes, 1);
85  if (!infoTemp)
86    return false;
87
88  auto remainder = infoTemp->Divide(generator);
89  if (!remainder)
90    return false;
91
92  const auto& coefficients = remainder->GetCoefficients();
93  size_t numZeroCoefficients =
94      ecBytes > coefficients.size() ? ecBytes - coefficients.size() : 0;
95  for (size_t i = 0; i < numZeroCoefficients; i++)
96    (*toEncode)[dataBytes + i] = 0;
97  for (size_t y = 0; y < coefficients.size(); y++)
98    (*toEncode)[dataBytes + numZeroCoefficients + y] = coefficients[y];
99  return true;
100}
101