private GenericGFPoly buildGenerator(int degree) {
if (degree >= cachedGenerators.size()) {
GenericGFPoly lastGenerator = cachedGenerators.get(cachedGenerators.size() - 1);
for (int d = cachedGenerators.size(); d <= degree; d++) {
GenericGFPoly nextGenerator =
lastGenerator.multiply(new GenericGFPoly(field, new int[] {1, field.exp(d - 1)}));
cachedGenerators.add(nextGenerator);
lastGenerator = nextGenerator;
}
}
return cachedGenerators.get(degree);
}
public void encode(int[] toEncode, int ecBytes) {
if (ecBytes == 0) {
throw new IllegalArgumentException("No error correction bytes");
}
int dataBytes = toEncode.length - ecBytes;
if (dataBytes <= 0) {
throw new IllegalArgumentException("No data bytes provided");
}
// MANUELLA: build the message polynomial
GenericGFPoly generator = buildGenerator(ecBytes);
int[] infoCoefficients = new int[dataBytes];
System.arraycopy(toEncode, 0, infoCoefficients, 0, dataBytes);
// MANUELLA
System.out.print(" ");
for (int i = 0; i < infoCoefficients.length; i++) {
System.out.print("" + infoCoefficients[i] + ",");
}
System.out.println();
GenericGFPoly info = new GenericGFPoly(field, infoCoefficients);
info = info.multiplyByMonomial(ecBytes, 1);
// MANUELLA
System.out.println(" message polynomial: " + info.toString());
System.out.println(" generator polynomial: " + generator.toString());
GenericGFPoly remainder = info.divide(generator)[1];
int[] coefficients = remainder.getCoefficients();
// MANUELLA
System.out.print(" ");
for (int i = 0; i < coefficients.length; i++) {
System.out.print("" + coefficients[i] + ",");
}
System.out.println();
int numZeroCoefficients = ecBytes - coefficients.length;
// MANUELLA
System.out.println(" polynomial: " + remainder.toString());
for (int i = 0; i < numZeroCoefficients; i++) {
toEncode[dataBytes + i] = 0;
}
System.arraycopy(
coefficients, 0, toEncode, dataBytes + numZeroCoefficients, coefficients.length);
}
public void encode(int[] toEncode, int ecBytes) {
if (ecBytes == 0) {
throw new IllegalArgumentException("No error correction bytes");
}
int dataBytes = toEncode.length - ecBytes;
if (dataBytes <= 0) {
throw new IllegalArgumentException("No data bytes provided");
}
GenericGFPoly generator = buildGenerator(ecBytes);
int[] infoCoefficients = new int[dataBytes];
System.arraycopy(toEncode, 0, infoCoefficients, 0, dataBytes);
GenericGFPoly info = new GenericGFPoly(field, infoCoefficients);
info = info.multiplyByMonomial(ecBytes, 1);
GenericGFPoly remainder = info.divide(generator)[1];
int[] coefficients = remainder.getCoefficients();
int numZeroCoefficients = ecBytes - coefficients.length;
for (int i = 0; i < numZeroCoefficients; i++) {
toEncode[dataBytes + i] = 0;
}
System.arraycopy(
coefficients, 0, toEncode, dataBytes + numZeroCoefficients, coefficients.length);
}