private static bool is_codeword_valid(int[] codeword)
{
int sum = 0;
for (int i = 1; i < 5; i++)
{
int t = 0;
for (int j = 0; j < 31; j++)
{
if (j > 12 && j < 27)
{
continue;
}
int pos = j;
if (j > 26)
{
pos -= 14;
}
t ^= ReedSolomon.gmult(codeword[pos], ReedSolomon.gexp[(i * j) % 31]);
}
sum |= t;
}
return(sum == 0);
}
public static String Encode(ulong plain)
{
String plain_string = Convert.ToString(plain);
int length = plain_string.Length;
int[] plain_string_10 = new int[ReedSolomon.base_10_length];
for (int i = 0; i < length; i++)
{
plain_string_10[i] = (int)plain_string[i] - (int)'0';
}
int codeword_length = 0;
int[] codeword = new int[ReedSolomon.initial_codeword.Length];
do
{ // base 10 to base 32 conversion
int new_length = 0;
int digit_32 = 0;
for (int i = 0; i < length; i++)
{
digit_32 = digit_32 * 10 + plain_string_10[i];
if (digit_32 >= 32)
{
plain_string_10[new_length] = digit_32 >> 5;
digit_32 &= 31;
new_length += 1;
}
else if (new_length > 0)
{
plain_string_10[new_length] = 0;
new_length += 1;
}
}
length = new_length;
codeword[codeword_length] = digit_32;
codeword_length += 1;
} while (length > 0);
int[] p = { 0, 0, 0, 0 };
for (int i = ReedSolomon.base_32_length - 1; i >= 0; i--)
{
int fb = codeword[i] ^ p[3];
p[3] = p[2] ^ ReedSolomon.gmult(30, fb);
p[2] = p[1] ^ ReedSolomon.gmult(6, fb);
p[1] = p[0] ^ ReedSolomon.gmult(9, fb);
p[0] = ReedSolomon.gmult(17, fb);
}
Array.Copy(p, 0, codeword, ReedSolomon.base_32_length, ReedSolomon.initial_codeword.Length - ReedSolomon.base_32_length);
StringBuilder cypher_string_builder = new StringBuilder();
for (int i = 0; i < 17; i++)
{
int codework_index = ReedSolomon.codeword_map[i];
int alphabet_index = codeword[codework_index];
cypher_string_builder.Append(ReedSolomon.alphabet[alphabet_index]);
if ((i & 3) == 3 && i < 13)
{
cypher_string_builder.Append('-');
}
}
return(cypher_string_builder.ToString());
}
