1 // Copyright 2014 PDFium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 
5 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
6 // Original code is licensed as follows:
7 /*
8  * Copyright 2007 ZXing authors
9  *
10  * Licensed under the Apache License, Version 2.0 (the "License");
11  * you may not use this file except in compliance with the License.
12  * You may obtain a copy of the License at
13  *
14  *      http://www.apache.org/licenses/LICENSE-2.0
15  *
16  * Unless required by applicable law or agreed to in writing, software
17  * distributed under the License is distributed on an "AS IS" BASIS,
18  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
19  * See the License for the specific language governing permissions and
20  * limitations under the License.
21  */
22 
23 #include "xfa/src/fxbarcode/barcode.h"
24 #include "BC_ReedSolomonGF256.h"
25 #include "BC_ReedSolomonGF256Poly.h"
26 #include "BC_ReedSolomonDecoder.h"
CBC_ReedSolomonDecoder(CBC_ReedSolomonGF256 * field)27 CBC_ReedSolomonDecoder::CBC_ReedSolomonDecoder(CBC_ReedSolomonGF256* field) {
28   m_field = field;
29 }
~CBC_ReedSolomonDecoder()30 CBC_ReedSolomonDecoder::~CBC_ReedSolomonDecoder() {}
Decode(CFX_Int32Array * received,int32_t twoS,int32_t & e)31 void CBC_ReedSolomonDecoder::Decode(CFX_Int32Array* received,
32                                     int32_t twoS,
33                                     int32_t& e) {
34   CBC_ReedSolomonGF256Poly poly;
35   poly.Init(m_field, received, e);
36   BC_EXCEPTION_CHECK_ReturnVoid(e);
37   CFX_Int32Array syndromeCoefficients;
38   syndromeCoefficients.SetSize(twoS);
39   FX_BOOL dataMatrix = FALSE;
40   FX_BOOL noError = TRUE;
41   for (int32_t i = 0; i < twoS; i++) {
42     int32_t eval = poly.EvaluateAt(m_field->Exp(dataMatrix ? i + 1 : i));
43     syndromeCoefficients[twoS - 1 - i] = eval;
44     if (eval != 0) {
45       noError = FALSE;
46     }
47   }
48   if (noError) {
49     return;
50   }
51   CBC_ReedSolomonGF256Poly syndrome;
52   syndrome.Init(m_field, &syndromeCoefficients, e);
53   BC_EXCEPTION_CHECK_ReturnVoid(e);
54   CBC_ReedSolomonGF256Poly* rsg = m_field->BuildMonomial(twoS, 1, e);
55   BC_EXCEPTION_CHECK_ReturnVoid(e);
56   CBC_AutoPtr<CBC_ReedSolomonGF256Poly> temp(rsg);
57   CFX_PtrArray* pa = RunEuclideanAlgorithm(temp.get(), &syndrome, twoS, e);
58   BC_EXCEPTION_CHECK_ReturnVoid(e);
59   CBC_AutoPtr<CFX_PtrArray> sigmaOmega(pa);
60   CBC_AutoPtr<CBC_ReedSolomonGF256Poly> sigma(
61       (CBC_ReedSolomonGF256Poly*)(*sigmaOmega)[0]);
62   CBC_AutoPtr<CBC_ReedSolomonGF256Poly> omega(
63       (CBC_ReedSolomonGF256Poly*)(*sigmaOmega)[1]);
64   CFX_Int32Array* ia1 = FindErrorLocations(sigma.get(), e);
65   BC_EXCEPTION_CHECK_ReturnVoid(e);
66   CBC_AutoPtr<CFX_Int32Array> errorLocations(ia1);
67   CFX_Int32Array* ia2 =
68       FindErrorMagnitudes(omega.get(), errorLocations.get(), dataMatrix, e);
69   BC_EXCEPTION_CHECK_ReturnVoid(e);
70   CBC_AutoPtr<CFX_Int32Array> errorMagnitudes(ia2);
71   for (int32_t k = 0; k < errorLocations->GetSize(); k++) {
72     int32_t position =
73         received->GetSize() - 1 - m_field->Log((*errorLocations)[k], e);
74     BC_EXCEPTION_CHECK_ReturnVoid(e);
75     if (position < 0) {
76       e = BCExceptionBadErrorLocation;
77       BC_EXCEPTION_CHECK_ReturnVoid(e);
78     }
79     (*received)[position] = CBC_ReedSolomonGF256::AddOrSubtract(
80         (*received)[position], (*errorMagnitudes)[k]);
81   }
82 }
RunEuclideanAlgorithm(CBC_ReedSolomonGF256Poly * a,CBC_ReedSolomonGF256Poly * b,int32_t R,int32_t & e)83 CFX_PtrArray* CBC_ReedSolomonDecoder::RunEuclideanAlgorithm(
84     CBC_ReedSolomonGF256Poly* a,
85     CBC_ReedSolomonGF256Poly* b,
86     int32_t R,
87     int32_t& e) {
88   if (a->GetDegree() < b->GetDegree()) {
89     CBC_ReedSolomonGF256Poly* temp = a;
90     a = b;
91     b = temp;
92   }
93   CBC_ReedSolomonGF256Poly* rsg1 = a->Clone(e);
94   BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
95   CBC_AutoPtr<CBC_ReedSolomonGF256Poly> rLast(rsg1);
96   CBC_ReedSolomonGF256Poly* rsg2 = b->Clone(e);
97   BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
98   CBC_AutoPtr<CBC_ReedSolomonGF256Poly> r(rsg2);
99   CBC_ReedSolomonGF256Poly* rsg3 = m_field->GetOne()->Clone(e);
100   BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
101   CBC_AutoPtr<CBC_ReedSolomonGF256Poly> sLast(rsg3);
102   CBC_ReedSolomonGF256Poly* rsg4 = m_field->GetZero()->Clone(e);
103   BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
104   CBC_AutoPtr<CBC_ReedSolomonGF256Poly> s(rsg4);
105   CBC_ReedSolomonGF256Poly* rsg5 = m_field->GetZero()->Clone(e);
106   BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
107   CBC_AutoPtr<CBC_ReedSolomonGF256Poly> tLast(rsg5);
108   CBC_ReedSolomonGF256Poly* rsg6 = m_field->GetOne()->Clone(e);
109   BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
110   CBC_AutoPtr<CBC_ReedSolomonGF256Poly> t(rsg6);
111   while (r->GetDegree() >= R / 2) {
112     CBC_AutoPtr<CBC_ReedSolomonGF256Poly> rLastLast = rLast;
113     CBC_AutoPtr<CBC_ReedSolomonGF256Poly> sLastLast = sLast;
114     CBC_AutoPtr<CBC_ReedSolomonGF256Poly> tLastlast = tLast;
115     rLast = r;
116     sLast = s;
117     tLast = t;
118     if (rLast->IsZero()) {
119       e = BCExceptionR_I_1IsZero;
120       BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
121     }
122     CBC_ReedSolomonGF256Poly* rsg7 = rLastLast->Clone(e);
123     BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
124     CBC_AutoPtr<CBC_ReedSolomonGF256Poly> rTemp(rsg7);
125     r = rTemp;
126     CBC_ReedSolomonGF256Poly* rsg8 = m_field->GetZero()->Clone(e);
127     BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
128     CBC_AutoPtr<CBC_ReedSolomonGF256Poly> q(rsg8);
129     int32_t denominatorLeadingTerm = rLast->GetCoefficients(rLast->GetDegree());
130     int32_t dltInverse = m_field->Inverse(denominatorLeadingTerm, e);
131     BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
132     while (r->GetDegree() >= rLast->GetDegree() && !(r->IsZero())) {
133       int32_t degreeDiff = r->GetDegree() - rLast->GetDegree();
134       int32_t scale =
135           m_field->Multiply(r->GetCoefficients(r->GetDegree()), dltInverse);
136       CBC_ReedSolomonGF256Poly* rsgp1 =
137           m_field->BuildMonomial(degreeDiff, scale, e);
138       BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
139       CBC_AutoPtr<CBC_ReedSolomonGF256Poly> build(rsgp1);
140       CBC_ReedSolomonGF256Poly* rsgp2 = q->AddOrSubtract(build.get(), e);
141       BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
142       CBC_AutoPtr<CBC_ReedSolomonGF256Poly> temp(rsgp2);
143       q = temp;
144       CBC_ReedSolomonGF256Poly* rsgp3 =
145           rLast->MultiplyByMonomial(degreeDiff, scale, e);
146       BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
147       CBC_AutoPtr<CBC_ReedSolomonGF256Poly> multiply(rsgp3);
148       CBC_ReedSolomonGF256Poly* rsgp4 = r->AddOrSubtract(multiply.get(), e);
149       BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
150       CBC_AutoPtr<CBC_ReedSolomonGF256Poly> temp3(rsgp4);
151       r = temp3;
152     }
153     CBC_ReedSolomonGF256Poly* rsg9 = q->Multiply(sLast.get(), e);
154     BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
155     CBC_AutoPtr<CBC_ReedSolomonGF256Poly> temp1(rsg9);
156     CBC_ReedSolomonGF256Poly* rsg10 = temp1->AddOrSubtract(sLastLast.get(), e);
157     BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
158     CBC_AutoPtr<CBC_ReedSolomonGF256Poly> temp2(rsg10);
159     s = temp2;
160     CBC_ReedSolomonGF256Poly* rsg11 = q->Multiply(tLast.get(), e);
161     BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
162     CBC_AutoPtr<CBC_ReedSolomonGF256Poly> temp5(rsg11);
163     CBC_ReedSolomonGF256Poly* rsg12 = temp5->AddOrSubtract(tLastlast.get(), e);
164     BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
165     CBC_AutoPtr<CBC_ReedSolomonGF256Poly> temp6(rsg12);
166     t = temp6;
167   }
168   int32_t sigmaTildeAtZero = t->GetCoefficients(0);
169   if (sigmaTildeAtZero == 0) {
170     e = BCExceptionIsZero;
171     BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
172   }
173   int32_t inverse = m_field->Inverse(sigmaTildeAtZero, e);
174   BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
175   CBC_ReedSolomonGF256Poly* rsg13 = t->Multiply(inverse, e);
176   BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
177   CBC_AutoPtr<CBC_ReedSolomonGF256Poly> sigma(rsg13);
178   CBC_ReedSolomonGF256Poly* rsg14 = r->Multiply(inverse, e);
179   BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
180   CBC_AutoPtr<CBC_ReedSolomonGF256Poly> omega(rsg14);
181   CFX_PtrArray* temp = new CFX_PtrArray;
182   temp->Add(sigma.release());
183   temp->Add(omega.release());
184   return temp;
185 }
FindErrorLocations(CBC_ReedSolomonGF256Poly * errorLocator,int32_t & e)186 CFX_Int32Array* CBC_ReedSolomonDecoder::FindErrorLocations(
187     CBC_ReedSolomonGF256Poly* errorLocator,
188     int32_t& e) {
189   int32_t numErrors = errorLocator->GetDegree();
190   if (numErrors == 1) {
191     CBC_AutoPtr<CFX_Int32Array> temp(new CFX_Int32Array);
192     temp->Add(errorLocator->GetCoefficients(1));
193     return temp.release();
194   }
195   CFX_Int32Array* tempT = new CFX_Int32Array;
196   tempT->SetSize(numErrors);
197   CBC_AutoPtr<CFX_Int32Array> result(tempT);
198   int32_t ie = 0;
199   for (int32_t i = 1; i < 256 && ie < numErrors; i++) {
200     if (errorLocator->EvaluateAt(i) == 0) {
201       (*result)[ie] = m_field->Inverse(i, ie);
202       BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
203       ie++;
204     }
205   }
206   if (ie != numErrors) {
207     e = BCExceptionDegreeNotMatchRoots;
208     BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
209   }
210   return result.release();
211 }
FindErrorMagnitudes(CBC_ReedSolomonGF256Poly * errorEvaluator,CFX_Int32Array * errorLocations,FX_BOOL dataMatrix,int32_t & e)212 CFX_Int32Array* CBC_ReedSolomonDecoder::FindErrorMagnitudes(
213     CBC_ReedSolomonGF256Poly* errorEvaluator,
214     CFX_Int32Array* errorLocations,
215     FX_BOOL dataMatrix,
216     int32_t& e) {
217   int32_t s = errorLocations->GetSize();
218   CFX_Int32Array* temp = new CFX_Int32Array;
219   temp->SetSize(s);
220   CBC_AutoPtr<CFX_Int32Array> result(temp);
221   for (int32_t i = 0; i < s; i++) {
222     int32_t xiInverse = m_field->Inverse(errorLocations->operator[](i), e);
223     BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
224     int32_t denominator = 1;
225     for (int32_t j = 0; j < s; j++) {
226       if (i != j) {
227         denominator = m_field->Multiply(
228             denominator, CBC_ReedSolomonGF256::AddOrSubtract(
229                              1, m_field->Multiply(errorLocations->operator[](j),
230                                                   xiInverse)));
231       }
232     }
233     int32_t temp = m_field->Inverse(denominator, temp);
234     BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
235     (*result)[i] =
236         m_field->Multiply(errorEvaluator->EvaluateAt(xiInverse), temp);
237   }
238   return result.release();
239 }
240