private static int GetDestBytes(ulong number)
{
for (int i = 0; i < sizeof(ulong); i++)
{
if (number < (ulong)1 << (8 * (i + 1) - 1) >> i)
{
return i + 1;
}
}
if ((number & ((ulong)1 << 63)) != 0)
{
return sizeof(ulong) + 2;
}
return sizeof(ulong) + 1;
}
private static int GetMinBytes(ulong number)
{
for (int i = 0; i < sizeof(ulong) - 1; i++)
{
if (number < (ulong)1 << (8 * (i + 1)))
{
return i + 1;
}
}
return sizeof(ulong);
}
public static byte[] GetVariant_my(ulong number)
{
int destLength = GetDestBytes(number);
if (destLength == 1) //nothing to encode
{
return new byte[]
{
(byte)number
};
}
byte[] byteArray = BitConverter.GetBytes(number).Take(GetMinBytes(number)).ToArray();
byte[] destArray = new byte[destLength];
//save first 1 bit
byte prevFirstBits = (byte)((uint)byteArray[0] >> 7);
destArray[0] = (byte)(byteArray[0] | 128); // set msb = 1
for (int i = 1; i < byteArray.Length; i++)
{
var firstBits = (byte)((uint)byteArray[i] >> (8 - i - 1));
//shift to right and apply saved bits from prev octet
destArray[i] = (byte)(byteArray[i] << i | prevFirstBits);
//for non-last octet set msb = 1
if (i < destLength - 1)
{
destArray[i] = (byte)(destArray[i] | 128);
}
prevFirstBits = firstBits;
}
// apply prev saved bit to last byte
if (prevFirstBits != 0)
{
destArray[byteArray.Length] = prevFirstBits;
}
//for numbers > 2^63 need to save msb
if (destArray.Length == 10)
{
destArray[^1] = 1;
}
return destArray;
}
