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_ReedSolomonGF256Poly.h"
24
25#include <memory>
26#include <utility>
27
28#include "fxbarcode/common/reedsolomon/BC_ReedSolomonGF256.h"
29#include "third_party/base/ptr_util.h"
30#include "third_party/base/stl_util.h"
31
32CBC_ReedSolomonGF256Poly::CBC_ReedSolomonGF256Poly(CBC_ReedSolomonGF256* field,
33                                                   int32_t coefficients) {
34  if (!field)
35    return;
36
37  m_field = field;
38  m_coefficients.push_back(coefficients);
39}
40
41CBC_ReedSolomonGF256Poly::CBC_ReedSolomonGF256Poly() {
42  m_field = nullptr;
43}
44
45bool CBC_ReedSolomonGF256Poly::Init(CBC_ReedSolomonGF256* field,
46                                    const std::vector<int32_t>* coefficients) {
47  if (!coefficients || coefficients->empty())
48    return false;
49
50  m_field = field;
51  size_t coefficientsLength = coefficients->size();
52  if (coefficientsLength > 1 && coefficients->front() == 0) {
53    size_t firstNonZero = 1;
54    while (firstNonZero < coefficientsLength &&
55           (*coefficients)[firstNonZero] == 0) {
56      firstNonZero++;
57    }
58    if (firstNonZero == coefficientsLength) {
59      m_coefficients = m_field->GetZero()->GetCoefficients();
60    } else {
61      m_coefficients.resize(coefficientsLength - firstNonZero);
62      for (size_t i = firstNonZero, j = 0; i < coefficientsLength; i++, j++)
63        m_coefficients[j] = (*coefficients)[i];
64    }
65  } else {
66    m_coefficients = *coefficients;
67  }
68  return true;
69}
70
71const std::vector<int32_t>& CBC_ReedSolomonGF256Poly::GetCoefficients() const {
72  return m_coefficients;
73}
74
75int32_t CBC_ReedSolomonGF256Poly::GetDegree() const {
76  return pdfium::CollectionSize<int32_t>(m_coefficients) - 1;
77}
78
79bool CBC_ReedSolomonGF256Poly::IsZero() const {
80  return m_coefficients.front() == 0;
81}
82
83int32_t CBC_ReedSolomonGF256Poly::GetCoefficients(int32_t degree) const {
84  return m_coefficients[m_coefficients.size() - 1 - degree];
85}
86
87int32_t CBC_ReedSolomonGF256Poly::EvaluateAt(int32_t a) {
88  if (a == 0)
89    return GetCoefficients(0);
90
91  size_t size = m_coefficients.size();
92  if (a == 1) {
93    int32_t result = 0;
94    for (size_t i = 0; i < size; i++)
95      result = CBC_ReedSolomonGF256::AddOrSubtract(result, m_coefficients[i]);
96    return result;
97  }
98  int32_t result = m_coefficients[0];
99  for (size_t j = 1; j < size; j++) {
100    result = CBC_ReedSolomonGF256::AddOrSubtract(m_field->Multiply(a, result),
101                                                 m_coefficients[j]);
102  }
103  return result;
104}
105
106std::unique_ptr<CBC_ReedSolomonGF256Poly> CBC_ReedSolomonGF256Poly::Clone()
107    const {
108  auto temp = pdfium::MakeUnique<CBC_ReedSolomonGF256Poly>();
109  if (!temp->Init(m_field.Get(), &m_coefficients))
110    return nullptr;
111  return temp;
112}
113
114std::unique_ptr<CBC_ReedSolomonGF256Poly>
115CBC_ReedSolomonGF256Poly::AddOrSubtract(const CBC_ReedSolomonGF256Poly* other) {
116  if (IsZero())
117    return other->Clone();
118  if (other->IsZero())
119    return Clone();
120
121  std::vector<int32_t> smallerCoefficients = m_coefficients;
122  std::vector<int32_t> largerCoefficients = other->GetCoefficients();
123  if (smallerCoefficients.size() > largerCoefficients.size())
124    std::swap(smallerCoefficients, largerCoefficients);
125
126  std::vector<int32_t> sumDiff(largerCoefficients.size());
127  size_t lengthDiff = largerCoefficients.size() - smallerCoefficients.size();
128  for (size_t i = 0; i < lengthDiff; i++)
129    sumDiff[i] = largerCoefficients[i];
130
131  for (size_t j = lengthDiff; j < largerCoefficients.size(); j++) {
132    sumDiff[j] = CBC_ReedSolomonGF256::AddOrSubtract(
133        smallerCoefficients[j - lengthDiff], largerCoefficients[j]);
134  }
135  auto temp = pdfium::MakeUnique<CBC_ReedSolomonGF256Poly>();
136  if (!temp->Init(m_field.Get(), &sumDiff))
137    return nullptr;
138  return temp;
139}
140
141std::unique_ptr<CBC_ReedSolomonGF256Poly> CBC_ReedSolomonGF256Poly::Multiply(
142    const CBC_ReedSolomonGF256Poly* other) {
143  if (IsZero() || other->IsZero())
144    return m_field->GetZero()->Clone();
145
146  const std::vector<int32_t>& aCoefficients = m_coefficients;
147  const std::vector<int32_t>& bCoefficients = other->GetCoefficients();
148  size_t aLength = aCoefficients.size();
149  size_t bLength = bCoefficients.size();
150  std::vector<int32_t> product(aLength + bLength - 1);
151  for (size_t i = 0; i < aLength; i++) {
152    int32_t aCoeff = aCoefficients[i];
153    for (size_t j = 0; j < bLength; j++) {
154      product[i + j] = CBC_ReedSolomonGF256::AddOrSubtract(
155          product[i + j], m_field->Multiply(aCoeff, bCoefficients[j]));
156    }
157  }
158  auto temp = pdfium::MakeUnique<CBC_ReedSolomonGF256Poly>();
159  if (!temp->Init(m_field.Get(), &product))
160    return nullptr;
161  return temp;
162}
163
164std::unique_ptr<CBC_ReedSolomonGF256Poly> CBC_ReedSolomonGF256Poly::Multiply(
165    int32_t scalar) {
166  if (scalar == 0)
167    return m_field->GetZero()->Clone();
168  if (scalar == 1)
169    return Clone();
170
171  size_t size = m_coefficients.size();
172  std::vector<int32_t> product(size);
173  for (size_t i = 0; i < size; i++)
174    product[i] = m_field->Multiply(m_coefficients[i], scalar);
175
176  auto temp = pdfium::MakeUnique<CBC_ReedSolomonGF256Poly>();
177  if (!temp->Init(m_field.Get(), &product))
178    return nullptr;
179  return temp;
180}
181
182std::unique_ptr<CBC_ReedSolomonGF256Poly>
183CBC_ReedSolomonGF256Poly::MultiplyByMonomial(int32_t degree,
184                                             int32_t coefficient) const {
185  if (degree < 0)
186    return nullptr;
187  if (coefficient == 0)
188    return m_field->GetZero()->Clone();
189
190  size_t size = m_coefficients.size();
191  std::vector<int32_t> product(size + degree);
192  for (size_t i = 0; i < size; i++)
193    product[i] = m_field->Multiply(m_coefficients[i], coefficient);
194
195  auto temp = pdfium::MakeUnique<CBC_ReedSolomonGF256Poly>();
196  if (!temp->Init(m_field.Get(), &product))
197    return nullptr;
198  return temp;
199}
200
201std::unique_ptr<CBC_ReedSolomonGF256Poly> CBC_ReedSolomonGF256Poly::Divide(
202    const CBC_ReedSolomonGF256Poly* other) {
203  if (other->IsZero())
204    return nullptr;
205
206  auto quotient = m_field->GetZero()->Clone();
207  if (!quotient)
208    return nullptr;
209  auto remainder = Clone();
210  if (!remainder)
211    return nullptr;
212
213  int e = BCExceptionNO;
214  int32_t denominatorLeadingTerm = other->GetCoefficients(other->GetDegree());
215  int32_t inverseDenominatorLeadingTeam =
216      m_field->Inverse(denominatorLeadingTerm, e);
217  if (e != BCExceptionNO)
218    return nullptr;
219  while (remainder->GetDegree() >= other->GetDegree() && !remainder->IsZero()) {
220    int32_t degreeDifference = remainder->GetDegree() - other->GetDegree();
221    int32_t scale =
222        m_field->Multiply(remainder->GetCoefficients((remainder->GetDegree())),
223                          inverseDenominatorLeadingTeam);
224    auto term = other->MultiplyByMonomial(degreeDifference, scale);
225    if (!term)
226      return nullptr;
227    auto iteratorQuotient = m_field->BuildMonomial(degreeDifference, scale, e);
228    if (e != BCExceptionNO)
229      return nullptr;
230    quotient = quotient->AddOrSubtract(iteratorQuotient.get());
231    if (!quotient)
232      return nullptr;
233    remainder = remainder->AddOrSubtract(term.get());
234    if (!remainder)
235      return nullptr;
236  }
237  return remainder;
238}
239
240CBC_ReedSolomonGF256Poly::~CBC_ReedSolomonGF256Poly() {}
241