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 }); }
// Method added by Sonic-The-Hedgehog-LNK1123 (github.com/Sonic-The-Hedgehog-LNK1123) // this method replaces original method "runEuclideanAlgorithm" internal GenericGFPoly runBerlekampMasseyAlgorithm(GenericGFPoly syndrome, int erasureCount) { GenericGFPoly sigma = new GenericGFPoly(field, new int[] { 1 }, false); GenericGFPoly old = new GenericGFPoly(field, new int[] { 1 }, false); for (int i = 0; i < (syndrome.Coefficients.Length - erasureCount); i++) { int delta = syndrome.getCoefficient(i); for (int j = 1; j < sigma.Coefficients.Length; j++) { delta ^= field.multiply(sigma.getCoefficient(j), syndrome.getCoefficient(i - j)); } List <int> oldList = new List <int>(old.Coefficients); oldList.Add(0); old = new GenericGFPoly(field, oldList.ToArray(), false); if (delta != 0) { if (old.Coefficients.Length > sigma.Coefficients.Length) { GenericGFPoly new_loc = old.multiply(delta); old = sigma.multiply(field.inverse(delta)); sigma = new_loc; } sigma = sigma.addOrSubtract(old.multiply(delta)); } } List <int> sigmaList = new List <int>(sigma.Coefficients); while (Convert.ToBoolean(sigmaList.Count) && sigmaList[0] == 0) { sigmaList.RemoveAt(0); } sigma = new GenericGFPoly(field, sigmaList.ToArray(), false); return(sigma); }