public override string toHex()
{
char[] hexChars = Buf.hexChars;
StringBuilder s = new StringBuilder(m_size*2);
for (int i=0; i<m_size; ++i)
{
int b = m_buf[i] & 0xFF;
s.Append(hexChars[b>>4]).Append(hexChars[b&0xf]);
}
return s.ToString();
}