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"
27CBC_ReedSolomonDecoder::CBC_ReedSolomonDecoder(CBC_ReedSolomonGF256* field) {
28  m_field = field;
29}
30CBC_ReedSolomonDecoder::~CBC_ReedSolomonDecoder() {}
31void 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}
83CFX_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}
186CFX_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}
212CFX_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