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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 "../../barcode.h"
#include "BC_ReedSolomonGF256.h"
#include "BC_ReedSolomonGF256Poly.h"
#include "BC_ReedSolomonDecoder.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);
CBC_ReedSolomonGF256Poly* rsg = m_field->BuildMonomial(twoS, 1, e);
BC_EXCEPTION_CHECK_ReturnVoid(e);
CBC_AutoPtr<CBC_ReedSolomonGF256Poly> temp(rsg);
CFX_PtrArray* pa = RunEuclideanAlgorithm(temp.get(), &syndrome, twoS, e);
BC_EXCEPTION_CHECK_ReturnVoid(e);
CBC_AutoPtr<CFX_PtrArray> sigmaOmega(pa);
CBC_AutoPtr<CBC_ReedSolomonGF256Poly> sigma(
(CBC_ReedSolomonGF256Poly*)(*sigmaOmega)[0]);
CBC_AutoPtr<CBC_ReedSolomonGF256Poly> omega(
(CBC_ReedSolomonGF256Poly*)(*sigmaOmega)[1]);
CFX_Int32Array* ia1 = FindErrorLocations(sigma.get(), e);
BC_EXCEPTION_CHECK_ReturnVoid(e);
CBC_AutoPtr<CFX_Int32Array> errorLocations(ia1);
CFX_Int32Array* ia2 =
FindErrorMagnitudes(omega.get(), errorLocations.get(), dataMatrix, e);
BC_EXCEPTION_CHECK_ReturnVoid(e);
CBC_AutoPtr<CFX_Int32Array> errorMagnitudes(ia2);
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_PtrArray* 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;
}
CBC_ReedSolomonGF256Poly* rsg1 = a->Clone(e);
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
CBC_AutoPtr<CBC_ReedSolomonGF256Poly> rLast(rsg1);
CBC_ReedSolomonGF256Poly* rsg2 = b->Clone(e);
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
CBC_AutoPtr<CBC_ReedSolomonGF256Poly> r(rsg2);
CBC_ReedSolomonGF256Poly* rsg3 = m_field->GetOne()->Clone(e);
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
CBC_AutoPtr<CBC_ReedSolomonGF256Poly> sLast(rsg3);
CBC_ReedSolomonGF256Poly* rsg4 = m_field->GetZero()->Clone(e);
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
CBC_AutoPtr<CBC_ReedSolomonGF256Poly> s(rsg4);
CBC_ReedSolomonGF256Poly* rsg5 = m_field->GetZero()->Clone(e);
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
CBC_AutoPtr<CBC_ReedSolomonGF256Poly> tLast(rsg5);
CBC_ReedSolomonGF256Poly* rsg6 = m_field->GetOne()->Clone(e);
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
CBC_AutoPtr<CBC_ReedSolomonGF256Poly> t(rsg6);
while (r->GetDegree() >= R / 2) {
CBC_AutoPtr<CBC_ReedSolomonGF256Poly> rLastLast = rLast;
CBC_AutoPtr<CBC_ReedSolomonGF256Poly> sLastLast = sLast;
CBC_AutoPtr<CBC_ReedSolomonGF256Poly> tLastlast = tLast;
rLast = r;
sLast = s;
tLast = t;
if (rLast->IsZero()) {
e = BCExceptionR_I_1IsZero;
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
}
CBC_ReedSolomonGF256Poly* rsg7 = rLastLast->Clone(e);
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
CBC_AutoPtr<CBC_ReedSolomonGF256Poly> rTemp(rsg7);
r = rTemp;
CBC_ReedSolomonGF256Poly* rsg8 = m_field->GetZero()->Clone(e);
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
CBC_AutoPtr<CBC_ReedSolomonGF256Poly> q(rsg8);
int32_t denominatorLeadingTerm = rLast->GetCoefficients(rLast->GetDegree());
int32_t dltInverse = m_field->Inverse(denominatorLeadingTerm, e);
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
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);
CBC_ReedSolomonGF256Poly* rsgp1 =
m_field->BuildMonomial(degreeDiff, scale, e);
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
CBC_AutoPtr<CBC_ReedSolomonGF256Poly> build(rsgp1);
CBC_ReedSolomonGF256Poly* rsgp2 = q->AddOrSubtract(build.get(), e);
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
CBC_AutoPtr<CBC_ReedSolomonGF256Poly> temp(rsgp2);
q = temp;
CBC_ReedSolomonGF256Poly* rsgp3 =
rLast->MultiplyByMonomial(degreeDiff, scale, e);
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
CBC_AutoPtr<CBC_ReedSolomonGF256Poly> multiply(rsgp3);
CBC_ReedSolomonGF256Poly* rsgp4 = r->AddOrSubtract(multiply.get(), e);
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
CBC_AutoPtr<CBC_ReedSolomonGF256Poly> temp3(rsgp4);
r = temp3;
}
CBC_ReedSolomonGF256Poly* rsg9 = q->Multiply(sLast.get(), e);
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
CBC_AutoPtr<CBC_ReedSolomonGF256Poly> temp1(rsg9);
CBC_ReedSolomonGF256Poly* rsg10 = temp1->AddOrSubtract(sLastLast.get(), e);
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
CBC_AutoPtr<CBC_ReedSolomonGF256Poly> temp2(rsg10);
s = temp2;
CBC_ReedSolomonGF256Poly* rsg11 = q->Multiply(tLast.get(), e);
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
CBC_AutoPtr<CBC_ReedSolomonGF256Poly> temp5(rsg11);
CBC_ReedSolomonGF256Poly* rsg12 = temp5->AddOrSubtract(tLastlast.get(), e);
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
CBC_AutoPtr<CBC_ReedSolomonGF256Poly> temp6(rsg12);
t = temp6;
}
int32_t sigmaTildeAtZero = t->GetCoefficients(0);
if (sigmaTildeAtZero == 0) {
e = BCExceptionIsZero;
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
}
int32_t inverse = m_field->Inverse(sigmaTildeAtZero, e);
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
CBC_ReedSolomonGF256Poly* rsg13 = t->Multiply(inverse, e);
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
CBC_AutoPtr<CBC_ReedSolomonGF256Poly> sigma(rsg13);
CBC_ReedSolomonGF256Poly* rsg14 = r->Multiply(inverse, e);
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
CBC_AutoPtr<CBC_ReedSolomonGF256Poly> omega(rsg14);
CFX_PtrArray* temp = FX_NEW CFX_PtrArray;
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) {
CBC_AutoPtr<CFX_Int32Array> temp(FX_NEW CFX_Int32Array);
temp->Add(errorLocator->GetCoefficients(1));
return temp.release();
}
CFX_Int32Array* tempT = FX_NEW CFX_Int32Array;
tempT->SetSize(numErrors);
CBC_AutoPtr<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* temp = FX_NEW CFX_Int32Array;
temp->SetSize(s);
CBC_AutoPtr<CFX_Int32Array> result(temp);
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, temp);
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
(*result)[i] =
m_field->Multiply(errorEvaluator->EvaluateAt(xiInverse), temp);
}
return result.release();
}
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