CBC_ReedSolomonGF256Poly* CBC_ReedSolomonGF256Poly::Multiply(
CBC_ReedSolomonGF256Poly* other,
int32_t& e) {
if (IsZero() || other->IsZero()) {
CBC_ReedSolomonGF256Poly* temp = m_field->GetZero()->Clone(e);
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
return temp;
}
CFX_Int32Array aCoefficients;
aCoefficients.Copy(m_coefficients);
int32_t aLength = m_coefficients.GetSize();
CFX_Int32Array bCoefficients;
bCoefficients.Copy(*(other->GetCoefficients()));
int32_t bLength = other->GetCoefficients()->GetSize();
CFX_Int32Array product;
product.SetSize(aLength + bLength - 1);
for (int32_t i = 0; i < aLength; i++) {
int32_t aCoeff = m_coefficients[i];
for (int32_t j = 0; j < bLength; j++) {
product[i + j] = CBC_ReedSolomonGF256::AddOrSubtract(
product[i + j],
m_field->Multiply(aCoeff, other->GetCoefficients()->operator[](j)));
}
}
CBC_ReedSolomonGF256Poly* temp = new CBC_ReedSolomonGF256Poly();
temp->Init(m_field, &product, e);
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
return temp;
}
CBC_ReedSolomonGF256Poly* CBC_ReedSolomonGF256Poly::AddOrSubtract(
CBC_ReedSolomonGF256Poly* other,
int32_t& e) {
if (IsZero())
return other->Clone(e);
if (other->IsZero())
return Clone(e);
CFX_Int32Array smallerCoefficients;
smallerCoefficients.Copy(m_coefficients);
CFX_Int32Array largerCoefficients;
largerCoefficients.Copy(*(other->GetCoefficients()));
if (smallerCoefficients.GetSize() > largerCoefficients.GetSize()) {
CFX_Int32Array temp;
temp.Copy(smallerCoefficients);
smallerCoefficients.Copy(largerCoefficients);
largerCoefficients.Copy(temp);
}
CFX_Int32Array sumDiff;
sumDiff.SetSize(largerCoefficients.GetSize());
int32_t lengthDiff =
largerCoefficients.GetSize() - smallerCoefficients.GetSize();
for (int32_t i = 0; i < lengthDiff; i++) {
sumDiff[i] = largerCoefficients[i];
}
for (int32_t j = lengthDiff; j < largerCoefficients.GetSize(); j++) {
sumDiff[j] = (CBC_ReedSolomonGF256::AddOrSubtract(
smallerCoefficients[j - lengthDiff], largerCoefficients[j]));
}
CBC_ReedSolomonGF256Poly* temp = new CBC_ReedSolomonGF256Poly();
temp->Init(m_field, &sumDiff, e);
BC_EXCEPTION_CHECK_ReturnValue(e, nullptr);
return temp;
}
void CBC_ReedSolomonDecoder::Decode(CFX_Int32Array* received,
int32_t twoS,
int32_t& 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 (int32_t i = 0; i < twoS; i++) {
int32_t 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 (int32_t k = 0; k < errorLocations->GetSize(); k++) {
int32_t 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]);
}
}
CBC_ReedSolomonGF256Poly* CBC_ReedSolomonGF256Poly::Multiply(int32_t scalar,
int32_t& e) {
if (scalar == 0)
return m_field->GetZero()->Clone(e);
if (scalar == 1)
return Clone(e);
int32_t size = m_coefficients.GetSize();
CFX_Int32Array product;
product.SetSize(size);
for (int32_t i = 0; i < size; i++) {
product[i] = m_field->Multiply(m_coefficients[i], scalar);
}
CBC_ReedSolomonGF256Poly* temp = new CBC_ReedSolomonGF256Poly();
temp->Init(m_field, &product, e);
BC_EXCEPTION_CHECK_ReturnValue(e, nullptr);
return temp;
}
CBC_ReedSolomonGF256Poly* CBC_ReedSolomonGF256Poly::MultiplyByMonomial(
int32_t degree,
int32_t coefficient,
int32_t& e) {
if (degree < 0) {
e = BCExceptionDegreeIsNegative;
return nullptr;
}
if (coefficient == 0)
return m_field->GetZero()->Clone(e);
int32_t size = m_coefficients.GetSize();
CFX_Int32Array product;
product.SetSize(size + degree);
for (int32_t i = 0; i < size; i++) {
product[i] = (m_field->Multiply(m_coefficients[i], coefficient));
}
CBC_ReedSolomonGF256Poly* temp = new CBC_ReedSolomonGF256Poly();
temp->Init(m_field, &product, e);
BC_EXCEPTION_CHECK_ReturnValue(e, nullptr);
return temp;
}
CBC_ReedSolomonGF256Poly* CBC_ReedSolomonGF256Poly::Clone(int32_t& e) {
CBC_ReedSolomonGF256Poly* temp = new CBC_ReedSolomonGF256Poly();
temp->Init(m_field, &m_coefficients, e);
BC_EXCEPTION_CHECK_ReturnValue(e, NULL);
return temp;
}
