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// 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 "fxbarcode/common/reedsolomon/BC_ReedSolomonGF256.h"
#include <vector>
#include "fxbarcode/common/reedsolomon/BC_ReedSolomonGF256Poly.h"
CBC_ReedSolomonGF256::CBC_ReedSolomonGF256(int32_t primitive) {
int32_t x = 1;
for (int32_t j = 0; j < 256; j++) {
m_expTable[j] = x;
x <<= 1;
if (x >= 0x100) {
x ^= primitive;
}
}
for (int32_t i = 0; i < 255; i++) {
m_logTable[m_expTable[i]] = i;
}
m_logTable[0] = 0;
}
void CBC_ReedSolomonGF256::Init() {
m_zero =
std::make_unique<CBC_ReedSolomonGF256Poly>(this, std::vector<int32_t>{0});
m_one =
std::make_unique<CBC_ReedSolomonGF256Poly>(this, std::vector<int32_t>{1});
}
CBC_ReedSolomonGF256::~CBC_ReedSolomonGF256() = default;
std::unique_ptr<CBC_ReedSolomonGF256Poly> CBC_ReedSolomonGF256::BuildMonomial(
int32_t degree,
int32_t coefficient) {
if (degree < 0)
return nullptr;
if (coefficient == 0)
return m_zero->Clone();
std::vector<int32_t> coefficients(degree + 1);
coefficients[0] = coefficient;
return std::make_unique<CBC_ReedSolomonGF256Poly>(this, coefficients);
}
// static
int32_t CBC_ReedSolomonGF256::AddOrSubtract(int32_t a, int32_t b) {
return a ^ b;
}
int32_t CBC_ReedSolomonGF256::Exp(int32_t a) {
return m_expTable[a];
}
Optional<int32_t> CBC_ReedSolomonGF256::Inverse(int32_t a) {
if (a == 0)
return pdfium::nullopt;
return m_expTable[255 - m_logTable[a]];
}
int32_t CBC_ReedSolomonGF256::Multiply(int32_t a, int32_t b) {
if (a == 0 || b == 0) {
return 0;
}
if (a == 1) {
return b;
}
if (b == 1) {
return a;
}
return m_expTable[(m_logTable[a] + m_logTable[b]) % 255];
}