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// Copyright 2014 PDFium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
// Original code is licensed as follows:
/*
* Copyright 2007 ZXing authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "fxbarcode/common/reedsolomon/BC_ReedSolomonGF256Poly.h"
#include <memory>
#include <utility>
#include "core/fxcrt/fx_system.h"
#include "core/fxcrt/stl_util.h"
#include "fxbarcode/common/reedsolomon/BC_ReedSolomonGF256.h"
#include "third_party/base/check.h"
CBC_ReedSolomonGF256Poly::CBC_ReedSolomonGF256Poly(
CBC_ReedSolomonGF256* field,
const std::vector<int32_t>& coefficients)
: m_field(field) {
DCHECK(m_field);
DCHECK(!coefficients.empty());
if (coefficients.size() == 1 || coefficients.front() != 0) {
m_coefficients = coefficients;
return;
}
size_t firstNonZero = 1;
while (firstNonZero < coefficients.size() &&
coefficients[firstNonZero] == 0) {
firstNonZero++;
}
if (firstNonZero == coefficients.size()) {
m_coefficients = m_field->GetZero()->GetCoefficients();
} else {
m_coefficients.resize(coefficients.size() - firstNonZero);
for (size_t i = firstNonZero, j = 0; i < coefficients.size(); i++, j++)
m_coefficients[j] = coefficients[i];
}
}
CBC_ReedSolomonGF256Poly::~CBC_ReedSolomonGF256Poly() = default;
const std::vector<int32_t>& CBC_ReedSolomonGF256Poly::GetCoefficients() const {
return m_coefficients;
}
int32_t CBC_ReedSolomonGF256Poly::GetDegree() const {
return fxcrt::CollectionSize<int32_t>(m_coefficients) - 1;
}
bool CBC_ReedSolomonGF256Poly::IsZero() const {
return m_coefficients.front() == 0;
}
int32_t CBC_ReedSolomonGF256Poly::GetCoefficients(int32_t degree) const {
return m_coefficients[m_coefficients.size() - 1 - degree];
}
std::unique_ptr<CBC_ReedSolomonGF256Poly> CBC_ReedSolomonGF256Poly::Clone()
const {
return std::make_unique<CBC_ReedSolomonGF256Poly>(m_field.Get(),
m_coefficients);
}
std::unique_ptr<CBC_ReedSolomonGF256Poly>
CBC_ReedSolomonGF256Poly::AddOrSubtract(const CBC_ReedSolomonGF256Poly* other) {
if (IsZero())
return other->Clone();
if (other->IsZero())
return Clone();
std::vector<int32_t> smallerCoefficients = m_coefficients;
std::vector<int32_t> largerCoefficients = other->GetCoefficients();
if (smallerCoefficients.size() > largerCoefficients.size())
std::swap(smallerCoefficients, largerCoefficients);
std::vector<int32_t> sumDiff(largerCoefficients.size());
size_t lengthDiff = largerCoefficients.size() - smallerCoefficients.size();
for (size_t i = 0; i < lengthDiff; ++i)
sumDiff[i] = largerCoefficients[i];
for (size_t i = lengthDiff; i < largerCoefficients.size(); ++i) {
sumDiff[i] = CBC_ReedSolomonGF256::AddOrSubtract(
smallerCoefficients[i - lengthDiff], largerCoefficients[i]);
}
return std::make_unique<CBC_ReedSolomonGF256Poly>(m_field.Get(), sumDiff);
}
std::unique_ptr<CBC_ReedSolomonGF256Poly> CBC_ReedSolomonGF256Poly::Multiply(
const CBC_ReedSolomonGF256Poly* other) {
if (IsZero() || other->IsZero())
return m_field->GetZero()->Clone();
const std::vector<int32_t>& aCoefficients = m_coefficients;
const std::vector<int32_t>& bCoefficients = other->GetCoefficients();
size_t aLength = aCoefficients.size();
size_t bLength = bCoefficients.size();
std::vector<int32_t> product(aLength + bLength - 1);
for (size_t i = 0; i < aLength; i++) {
int32_t aCoeff = aCoefficients[i];
for (size_t j = 0; j < bLength; j++) {
product[i + j] = CBC_ReedSolomonGF256::AddOrSubtract(
product[i + j], m_field->Multiply(aCoeff, bCoefficients[j]));
}
}
return std::make_unique<CBC_ReedSolomonGF256Poly>(m_field.Get(), product);
}
std::unique_ptr<CBC_ReedSolomonGF256Poly>
CBC_ReedSolomonGF256Poly::MultiplyByMonomial(int32_t degree,
int32_t coefficient) const {
if (degree < 0)
return nullptr;
if (coefficient == 0)
return m_field->GetZero()->Clone();
size_t size = m_coefficients.size();
std::vector<int32_t> product(size + degree);
for (size_t i = 0; i < size; i++)
product[i] = m_field->Multiply(m_coefficients[i], coefficient);
return std::make_unique<CBC_ReedSolomonGF256Poly>(m_field.Get(), product);
}
std::unique_ptr<CBC_ReedSolomonGF256Poly> CBC_ReedSolomonGF256Poly::Divide(
const CBC_ReedSolomonGF256Poly* other) {
if (other->IsZero())
return nullptr;
auto quotient = m_field->GetZero()->Clone();
if (!quotient)
return nullptr;
auto remainder = Clone();
if (!remainder)
return nullptr;
int32_t denominatorLeadingTerm = other->GetCoefficients(other->GetDegree());
Optional<int32_t> inverseDenominatorLeadingTeam =
m_field->Inverse(denominatorLeadingTerm);
if (!inverseDenominatorLeadingTeam.has_value())
return nullptr;
while (remainder->GetDegree() >= other->GetDegree() && !remainder->IsZero()) {
int32_t degreeDifference = remainder->GetDegree() - other->GetDegree();
int32_t scale =
m_field->Multiply(remainder->GetCoefficients((remainder->GetDegree())),
inverseDenominatorLeadingTeam.value());
auto term = other->MultiplyByMonomial(degreeDifference, scale);
if (!term)
return nullptr;
auto iteratorQuotient = m_field->BuildMonomial(degreeDifference, scale);
if (!iteratorQuotient)
return nullptr;
quotient = quotient->AddOrSubtract(iteratorQuotient.get());
if (!quotient)
return nullptr;
remainder = remainder->AddOrSubtract(term.get());
if (!remainder)
return nullptr;
}
return remainder;
}