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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 "xfa/fxbarcode/common/reedsolomon/BC_ReedSolomonDecoder.h"
#include <memory>
#include <utility>
#include "xfa/fxbarcode/common/reedsolomon/BC_ReedSolomonGF256.h"
#include "xfa/fxbarcode/common/reedsolomon/BC_ReedSolomonGF256Poly.h"
CBC_ReedSolomonDecoder::CBC_ReedSolomonDecoder(CBC_ReedSolomonGF256* field) {
m_field = field;
}
CBC_ReedSolomonDecoder::~CBC_ReedSolomonDecoder() {}
void CBC_ReedSolomonDecoder::Decode(CFX_Int32Array* received,
int32_t twoS,
int32_t& e) {
CBC_ReedSolomonGF256Poly poly;
poly.Init(m_field, received, e);
BC_EXCEPTION_CHECK_ReturnVoid(e);
CFX_Int32Array syndromeCoefficients;
syndromeCoefficients.SetSize(twoS);
FX_BOOL dataMatrix = FALSE;
FX_BOOL noError = TRUE;
for (int32_t i = 0; i < twoS; i++) {
int32_t eval = poly.EvaluateAt(m_field->Exp(dataMatrix ? i + 1 : i));
syndromeCoefficients[twoS - 1 - i] = eval;
if (eval != 0) {
noError = FALSE;
}
}
if (noError) {
return;
}
CBC_ReedSolomonGF256Poly syndrome;
syndrome.Init(m_field, &syndromeCoefficients, e);
BC_EXCEPTION_CHECK_ReturnVoid(e);
std::unique_ptr<CBC_ReedSolomonGF256Poly> temp(
m_field->BuildMonomial(twoS, 1, e));
BC_EXCEPTION_CHECK_ReturnVoid(e);
std::unique_ptr<CFX_ArrayTemplate<CBC_ReedSolomonGF256Poly*>> sigmaOmega(
RunEuclideanAlgorithm(temp.get(), &syndrome, twoS, e));
BC_EXCEPTION_CHECK_ReturnVoid(e);
std::unique_ptr<CBC_ReedSolomonGF256Poly> sigma((*sigmaOmega)[0]);
std::unique_ptr<CBC_ReedSolomonGF256Poly> omega((*sigmaOmega)[1]);
std::unique_ptr<CFX_Int32Array> errorLocations(
FindErrorLocations(sigma.get(), e));
BC_EXCEPTION_CHECK_ReturnVoid(e);
std::unique_ptr<CFX_Int32Array> errorMagnitudes(
FindErrorMagnitudes(omega.get(), errorLocations.get(), dataMatrix, e));
BC_EXCEPTION_CHECK_ReturnVoid(e);
for (int32_t k = 0; k < errorLocations->GetSize(); k++) {
int32_t position =
received->GetSize() - 1 - m_field->Log((*errorLocations)[k], e);
BC_EXCEPTION_CHECK_ReturnVoid(e);
if (position < 0) {
e = BCExceptionBadErrorLocation;
BC_EXCEPTION_CHECK_ReturnVoid(e);
}
(*received)[position] = CBC_ReedSolomonGF256::AddOrSubtract(
(*received)[position], (*errorMagnitudes)[k]);
}
}
CFX_ArrayTemplate<CBC_ReedSolomonGF256Poly*>*
CBC_ReedSolomonDecoder::RunEuclideanAlgorithm(CBC_ReedSolomonGF256Poly* a,
CBC_ReedSolomonGF256Poly* b,
int32_t R,
int32_t& e) {
if (a->GetDegree() < b->GetDegree()) {
CBC_ReedSolomonGF256Poly* temp = a;
a = b;
b = temp;
}
std::unique_ptr<CBC_ReedSolomonGF256Poly> rLast(a->Clone(e));
BC_EXCEPTION_CHECK_ReturnValue(e, nullptr);
std::unique_ptr<CBC_ReedSolomonGF256Poly> r(b->Clone(e));
BC_EXCEPTION_CHECK_ReturnValue(e, nullptr);
std::unique_ptr<CBC_ReedSolomonGF256Poly> sLast(m_field->GetOne()->Clone(e));
BC_EXCEPTION_CHECK_ReturnValue(e, nullptr);
std::unique_ptr<CBC_ReedSolomonGF256Poly> s(m_field->GetZero()->Clone(e));
BC_EXCEPTION_CHECK_ReturnValue(e, nullptr);
std::unique_ptr<CBC_ReedSolomonGF256Poly> tLast(m_field->GetZero()->Clone(e));
BC_EXCEPTION_CHECK_ReturnValue(e, nullptr);
std::unique_ptr<CBC_ReedSolomonGF256Poly> t(m_field->GetOne()->Clone(e));
BC_EXCEPTION_CHECK_ReturnValue(e, nullptr);
while (r->GetDegree() >= R / 2) {
std::unique_ptr<CBC_ReedSolomonGF256Poly> rLastLast = std::move(rLast);
std::unique_ptr<CBC_ReedSolomonGF256Poly> sLastLast = std::move(sLast);
std::unique_ptr<CBC_ReedSolomonGF256Poly> tLastlast = std::move(tLast);
rLast = std::move(r);
sLast = std::move(s);
tLast = std::move(t);
if (rLast->IsZero()) {
e = BCExceptionR_I_1IsZero;
BC_EXCEPTION_CHECK_ReturnValue(e, nullptr);
}
r.reset(rLastLast->Clone(e));
BC_EXCEPTION_CHECK_ReturnValue(e, nullptr);
std::unique_ptr<CBC_ReedSolomonGF256Poly> q(m_field->GetZero()->Clone(e));
BC_EXCEPTION_CHECK_ReturnValue(e, nullptr);
int32_t denominatorLeadingTerm = rLast->GetCoefficients(rLast->GetDegree());
int32_t dltInverse = m_field->Inverse(denominatorLeadingTerm, e);
BC_EXCEPTION_CHECK_ReturnValue(e, nullptr);
while (r->GetDegree() >= rLast->GetDegree() && !(r->IsZero())) {
int32_t degreeDiff = r->GetDegree() - rLast->GetDegree();
int32_t scale =
m_field->Multiply(r->GetCoefficients(r->GetDegree()), dltInverse);
std::unique_ptr<CBC_ReedSolomonGF256Poly> build(
m_field->BuildMonomial(degreeDiff, scale, e));
BC_EXCEPTION_CHECK_ReturnValue(e, nullptr);
q.reset(q->AddOrSubtract(build.get(), e));
BC_EXCEPTION_CHECK_ReturnValue(e, nullptr);
std::unique_ptr<CBC_ReedSolomonGF256Poly> multiply(
rLast->MultiplyByMonomial(degreeDiff, scale, e));
BC_EXCEPTION_CHECK_ReturnValue(e, nullptr);
r.reset(r->AddOrSubtract(multiply.get(), e));
BC_EXCEPTION_CHECK_ReturnValue(e, nullptr);
}
std::unique_ptr<CBC_ReedSolomonGF256Poly> temp1(
q->Multiply(sLast.get(), e));
BC_EXCEPTION_CHECK_ReturnValue(e, nullptr);
s.reset(temp1->AddOrSubtract(sLastLast.get(), e));
BC_EXCEPTION_CHECK_ReturnValue(e, nullptr);
std::unique_ptr<CBC_ReedSolomonGF256Poly> temp5(
q->Multiply(tLast.get(), e));
BC_EXCEPTION_CHECK_ReturnValue(e, nullptr);
t.reset(temp5->AddOrSubtract(tLastlast.get(), e));
BC_EXCEPTION_CHECK_ReturnValue(e, nullptr);
}
int32_t sigmaTildeAtZero = t->GetCoefficients(0);
if (sigmaTildeAtZero == 0) {
e = BCExceptionIsZero;
BC_EXCEPTION_CHECK_ReturnValue(e, nullptr);
}
int32_t inverse = m_field->Inverse(sigmaTildeAtZero, e);
BC_EXCEPTION_CHECK_ReturnValue(e, nullptr);
std::unique_ptr<CBC_ReedSolomonGF256Poly> sigma(t->Multiply(inverse, e));
BC_EXCEPTION_CHECK_ReturnValue(e, nullptr);
std::unique_ptr<CBC_ReedSolomonGF256Poly> omega(r->Multiply(inverse, e));
BC_EXCEPTION_CHECK_ReturnValue(e, nullptr);
CFX_ArrayTemplate<CBC_ReedSolomonGF256Poly*>* temp =
new CFX_ArrayTemplate<CBC_ReedSolomonGF256Poly*>();
temp->Add(sigma.release());
temp->Add(omega.release());
return temp;
}
CFX_Int32Array* CBC_ReedSolomonDecoder::FindErrorLocations(
CBC_ReedSolomonGF256Poly* errorLocator,
int32_t& e) {
int32_t numErrors = errorLocator->GetDegree();
if (numErrors == 1) {
std::unique_ptr<CFX_Int32Array> temp(new CFX_Int32Array);
temp->Add(errorLocator->GetCoefficients(1));
return temp.release();
}
CFX_Int32Array* tempT = new CFX_Int32Array;
tempT->SetSize(numErrors);
std::unique_ptr<CFX_Int32Array> result(tempT);
int32_t ie = 0;
for (int32_t i = 1; i < 256 && ie < numErrors; i++) {
if (errorLocator->EvaluateAt(i) == 0) {
(*result)[ie] = m_field->Inverse(i, ie);
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
ie++;
}
}
if (ie != numErrors) {
e = BCExceptionDegreeNotMatchRoots;
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
}
return result.release();
}
CFX_Int32Array* CBC_ReedSolomonDecoder::FindErrorMagnitudes(
CBC_ReedSolomonGF256Poly* errorEvaluator,
CFX_Int32Array* errorLocations,
FX_BOOL dataMatrix,
int32_t& e) {
int32_t s = errorLocations->GetSize();
CFX_Int32Array* tempArray = new CFX_Int32Array;
tempArray->SetSize(s);
std::unique_ptr<CFX_Int32Array> result(tempArray);
for (int32_t i = 0; i < s; i++) {
int32_t xiInverse = m_field->Inverse(errorLocations->operator[](i), e);
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
int32_t denominator = 1;
for (int32_t j = 0; j < s; j++) {
if (i != j) {
denominator = m_field->Multiply(
denominator, CBC_ReedSolomonGF256::AddOrSubtract(
1, m_field->Multiply(errorLocations->operator[](j),
xiInverse)));
}
}
int32_t temp = m_field->Inverse(denominator, e);
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
(*result)[i] =
m_field->Multiply(errorEvaluator->EvaluateAt(xiInverse), temp);
}
return result.release();
}
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