// this method has been added by Sebastien ROBERT
// this implementation makes the mathematician-friendly approach programmer-friendly
public byte[] EncodeEx(byte[] toEncode, int ecBytes)
{
if (ecBytes == 0)
{
throw new ArgumentException("No error correction bytes");
}
int dataBytes = toEncode.Length - ecBytes;
if (dataBytes <= 0)
{
throw new ArgumentException("No data bytes provided");
}
GenericGFPoly generator = BuildGenerator(ecBytes);
int[] infoCoefficients = toEncode.Select(x => (int)x).ToArray();
var info = new GenericGFPoly(field, infoCoefficients);
info = info.MultiplyByMonomial(ecBytes, 1);
GenericGFPoly remainder = info.Divide(generator)[1];
int[] coefficients = remainder.Coefficients;
int numZeroCoefficients = ecBytes - coefficients.Length;
return(Enumerable.Repeat <byte>(0, numZeroCoefficients)
.Concat(coefficients.Select(x => (byte)x))
.ToArray());
}
internal GenericGFPoly[] Divide(GenericGFPoly other)
{
if (field.Equals(other.field) == false)
{
throw new ArgumentException("GenericGFPolys do not have same GenericGF field");
}
if (other.IsZero)
{
throw new ArgumentException("Divide by 0");
}
GenericGFPoly quotient = field.Zero;
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 = field.BuildMonomial(degreeDifference, scale);
quotient = quotient.AddOrSubtract(iterationQuotient);
remainder = remainder.AddOrSubtract(term);
}
return(new GenericGFPoly[] { quotient, remainder });
}
public void Encode(int[] toEncode, int ecBytes)
{
if (ecBytes == 0)
{
throw new ArgumentException("No error correction bytes");
}
int dataBytes = toEncode.Length - ecBytes;
if (dataBytes <= 0)
{
throw new ArgumentException("No data bytes provided");
}
GenericGFPoly generator = BuildGenerator(ecBytes);
var infoCoefficients = new int[dataBytes];
Array.Copy(toEncode, 0, infoCoefficients, 0, dataBytes);
var info = new GenericGFPoly(field, infoCoefficients);
info = info.MultiplyByMonomial(ecBytes, 1);
GenericGFPoly remainder = info.Divide(generator)[1];
int[] coefficients = remainder.Coefficients;
int numZeroCoefficients = ecBytes - coefficients.Length;
for (var i = 0; i < numZeroCoefficients; i++)
{
toEncode[dataBytes + i] = 0;
}
Array.Copy(coefficients, 0, toEncode, dataBytes + numZeroCoefficients, coefficients.Length);
}
