1 // Copyright 2014 The PDFium Authors
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 "fxbarcode/common/reedsolomon/BC_ReedSolomonGF256.h"
24
25 #include <vector>
26
27 #include "fxbarcode/common/reedsolomon/BC_ReedSolomonGF256Poly.h"
28
CBC_ReedSolomonGF256(int32_t primitive)29 CBC_ReedSolomonGF256::CBC_ReedSolomonGF256(int32_t primitive) {
30 int32_t x = 1;
31 for (int32_t j = 0; j < 256; j++) {
32 m_expTable[j] = x;
33 x <<= 1;
34 if (x >= 0x100) {
35 x ^= primitive;
36 }
37 }
38 for (int32_t i = 0; i < 255; i++) {
39 m_logTable[m_expTable[i]] = i;
40 }
41 m_logTable[0] = 0;
42 }
43
Init()44 void CBC_ReedSolomonGF256::Init() {
45 m_zero =
46 std::make_unique<CBC_ReedSolomonGF256Poly>(this, std::vector<int32_t>{0});
47 m_one =
48 std::make_unique<CBC_ReedSolomonGF256Poly>(this, std::vector<int32_t>{1});
49 }
50
51 CBC_ReedSolomonGF256::~CBC_ReedSolomonGF256() = default;
52
BuildMonomial(int32_t degree,int32_t coefficient)53 std::unique_ptr<CBC_ReedSolomonGF256Poly> CBC_ReedSolomonGF256::BuildMonomial(
54 int32_t degree,
55 int32_t coefficient) {
56 if (degree < 0)
57 return nullptr;
58
59 if (coefficient == 0)
60 return m_zero->Clone();
61
62 std::vector<int32_t> coefficients(degree + 1);
63 coefficients[0] = coefficient;
64 return std::make_unique<CBC_ReedSolomonGF256Poly>(this, coefficients);
65 }
66
67 // static
AddOrSubtract(int32_t a,int32_t b)68 int32_t CBC_ReedSolomonGF256::AddOrSubtract(int32_t a, int32_t b) {
69 return a ^ b;
70 }
71
Exp(int32_t a)72 int32_t CBC_ReedSolomonGF256::Exp(int32_t a) {
73 return m_expTable[a];
74 }
75
Inverse(int32_t a)76 absl::optional<int32_t> CBC_ReedSolomonGF256::Inverse(int32_t a) {
77 if (a == 0)
78 return absl::nullopt;
79 return m_expTable[255 - m_logTable[a]];
80 }
81
Multiply(int32_t a,int32_t b)82 int32_t CBC_ReedSolomonGF256::Multiply(int32_t a, int32_t b) {
83 if (a == 0 || b == 0) {
84 return 0;
85 }
86 if (a == 1) {
87 return b;
88 }
89 if (b == 1) {
90 return a;
91 }
92 return m_expTable[(m_logTable[a] + m_logTable[b]) % 255];
93 }
94