// 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, FX_INT32 twoS, FX_INT32 &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 (FX_INT32 i = 0; i < twoS; i++) { | |
FX_INT32 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 (FX_INT32 k = 0; k < errorLocations->GetSize(); k++) { | |
FX_INT32 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, FX_INT32 R, FX_INT32 &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); | |
FX_INT32 denominatorLeadingTerm = rLast->GetCoefficients(rLast->GetDegree()); | |
FX_INT32 dltInverse = m_field->Inverse(denominatorLeadingTerm, e); | |
BC_EXCEPTION_CHECK_ReturnValue(e, NULL); | |
while (r->GetDegree() >= rLast->GetDegree() && !(r->IsZero())) { | |
FX_INT32 degreeDiff = r->GetDegree() - rLast->GetDegree(); | |
FX_INT32 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; | |
} | |
FX_INT32 sigmaTildeAtZero = t->GetCoefficients(0); | |
if (sigmaTildeAtZero == 0) { | |
e = BCExceptionIsZero; | |
BC_EXCEPTION_CHECK_ReturnValue(e, NULL); | |
} | |
FX_INT32 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, FX_INT32 &e) | |
{ | |
FX_INT32 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); | |
FX_INT32 ie = 0; | |
for (FX_INT32 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, FX_INT32 &e) | |
{ | |
FX_INT32 s = errorLocations->GetSize(); | |
CFX_Int32Array * temp = FX_NEW CFX_Int32Array; | |
temp->SetSize(s); | |
CBC_AutoPtr<CFX_Int32Array > result(temp); | |
for (FX_INT32 i = 0; i < s; i++) { | |
FX_INT32 xiInverse = m_field->Inverse(errorLocations->operator [](i), e); | |
BC_EXCEPTION_CHECK_ReturnValue(e, NULL); | |
FX_INT32 denominator = 1; | |
for(FX_INT32 j = 0; j < s; j++) { | |
if(i != j) { | |
denominator = m_field->Multiply(denominator, | |
CBC_ReedSolomonGF256::AddOrSubtract(1, m_field->Multiply(errorLocations->operator [](j), xiInverse))); | |
} | |
} | |
FX_INT32 temp = m_field->Inverse(denominator, temp); | |
BC_EXCEPTION_CHECK_ReturnValue(e, NULL); | |
(*result)[i] = m_field->Multiply(errorEvaluator->EvaluateAt(xiInverse), | |
temp); | |
} | |
return result.release(); | |
} |