// 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(); }