internal GenericGFPoly[] divide(GenericGFPoly other)
{
if (!field.Equals(other.field))
{
throw new ArgumentException("GenericGFPolys do not have same GenericGF field");
}
if (other.isZero)
{
throw new ArgumentException("Divide by 0", "other");
}
GenericGFPoly quotient = new GenericGFPoly(field, new int[] { 0 }, encoding);
GenericGFPoly remainder = this;
int denominatorLeadingTerm = other.getCoefficient(other.Degree);
int inverseDenominatorLeadingTerm = field.inverse(denominatorLeadingTerm);
while (remainder.Degree >= other.Degree && !remainder.isZero)
{
int degreeDifference = remainder.Degree - other.Degree;
int scale = field.multiply(remainder.getCoefficient(remainder.Degree), inverseDenominatorLeadingTerm);
GenericGFPoly term = other.multiplyByMonomial(degreeDifference, scale);
GenericGFPoly iterationQuotient = buildMonomial(degreeDifference, scale);
quotient = quotient.addOrSubtract(iterationQuotient);
remainder = remainder.addOrSubtract(term);
}
return(new GenericGFPoly[] { quotient, remainder });
}
/// <summary>
/// Encodes given set of data codewords with Reed-Solomon.
/// </summary>
/// <param name="toEncode">data codewords and padding, the amount of padding should match
/// the number of error-correction codewords to generate. After encoding, the padding is
/// replaced with the error-correction codewords</param>
/// <param name="ecBytes">number of error-correction codewords to generate</param>
public void Encode(int[] toEncode, int ecBytes)
{
// Method modified by Sonic-The-Hedgehog-LNK1123 (github.com/Sonic-The-Hedgehog-LNK1123)
// added check for messages that are too long for the used Galois field
if (toEncode.Length >= field.Size)
{
throw new ArgumentException("Message is too long for this field", "toEncode");
}
if (ecBytes <= 0)
{
throw new ArgumentException("No error correction bytes provided", "ecBytes");
}
var dataBytes = toEncode.Length - ecBytes;
if (dataBytes <= 0)
{
throw new ArgumentException("No data bytes provided", "ecBytes");
}
var generator = buildGenerator(ecBytes);
var infoCoefficients = new int[dataBytes];
Array.Copy(toEncode, 0, infoCoefficients, 0, dataBytes);
var info = new GenericGFPoly(field, infoCoefficients, true);
info = info.multiplyByMonomial(ecBytes, 1);
var remainder = info.divide(generator)[1];
var coefficients = remainder.Coefficients;
var numZeroCoefficients = ecBytes - coefficients.Length;
for (var i = 0; i < numZeroCoefficients; i++)
{
toEncode[dataBytes + i] = 0;
}
Array.Copy(coefficients, 0, toEncode, dataBytes + numZeroCoefficients, coefficients.Length);
}
