Class GF2x

core/src/main/java/org/bouncycastle/pqc/crypto/hqc/GF2x.java:7–224

import org.bouncycastle.util.Pack;

class GF2x
{
    private final int bits;
    private final int size;
    private final int sizeExt;

    GF2x(int n)
    {
        if ((n & 0xFFFF0001) != 1)
            throw new IllegalArgumentException();

        bits = n;
        size = Utils.getByte64SizeFromBitSize(n);
        sizeExt = size * 2;
    }

    void addTo(long[] x, long[] z)
    {
        Nat.xorTo64(size, x, z);
    }

    void clear(long[] z)
    {
        Nat.zero64(size, z);
    }

    long[] create()
    {
        return new long[size];
    }

    long[] createExt()
    {
        return new long[sizeExt];
    }

    long equalTo(long[] x, long[] y)
    {
        return Nat.equalTo64(size, x, y);
    }

    void mul(long[] x, long[] y, long[] z)
    {
        long[] tt = createExt();
        long[] tmp = new long[size << 4];
        karatsuba(size, x, 0, y, 0, tt, 0, tmp, 0);
        reduce(tt, z);
    }

    void random(Shake256RandomGenerator generator, long[] z)
    {
        byte[] tmp = new byte[size << 3];
        generator.xofGetBytes(tmp, Utils.getByteSizeFromBitSize(bits));
        Pack.littleEndianToLong(tmp, 0, z);
        z[size - 1] &= (1L << (bits & 63)) - 1L;
    }

    /**