iTextSharp.text.pdf.qrcode.GF256Poly.AddOrSubtract C# (CSharp) Méthode

        internal GF256Poly AddOrSubtract(GF256Poly other) {
            if (!field.Equals(other.field)) {
                throw new ArgumentException("GF256Polys do not have same GF256 field");
            }
            if (IsZero()) {
                return other;
            }
            if (other.IsZero()) {
                return this;
            }

            int[] smallerCoefficients = this.coefficients;
            int[] largerCoefficients = other.coefficients;
            if (smallerCoefficients.Length > largerCoefficients.Length) {
                int[] temp = smallerCoefficients;
                smallerCoefficients = largerCoefficients;
                largerCoefficients = temp;
            }
            int[] sumDiff = new int[largerCoefficients.Length];
            int lengthDiff = largerCoefficients.Length - smallerCoefficients.Length;
            // Copy high-order terms only found in higher-degree polynomial's coefficients
            System.Array.Copy(largerCoefficients, 0, sumDiff, 0, lengthDiff);

            for (int i = lengthDiff; i < largerCoefficients.Length; i++) {
                sumDiff[i] = GF256.AddOrSubtract(smallerCoefficients[i - lengthDiff], largerCoefficients[i]);
            }

            return new GF256Poly(field, sumDiff);
        }

        internal GF256Poly[] Divide(GF256Poly other)
        {
            if (!field.Equals(other.field))
            {
                throw new ArgumentException("GF256Polys do not have same GF256 field");
            }
            if (other.IsZero())
            {
                throw new DivideByZeroException("Divide by 0");
            }

            GF256Poly quotient  = field.GetZero();
            GF256Poly remainder = this;

            int denominatorLeadingTerm        = other.GetCoefficient(other.GetDegree());
            int inverseDenominatorLeadingTerm = field.Inverse(denominatorLeadingTerm);

            while (remainder.GetDegree() >= other.GetDegree() && !remainder.IsZero())
            {
                int       degreeDifference  = remainder.GetDegree() - other.GetDegree();
                int       scale             = field.Multiply(remainder.GetCoefficient(remainder.GetDegree()), inverseDenominatorLeadingTerm);
                GF256Poly term              = other.MultiplyByMonomial(degreeDifference, scale);
                GF256Poly iterationQuotient = field.BuildMonomial(degreeDifference, scale);
                quotient  = quotient.AddOrSubtract(iterationQuotient);
                remainder = remainder.AddOrSubtract(term);
            }

            return(new GF256Poly[] { quotient, remainder });
        }