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mystring binarytohex(mystring source)
{
  int i;
  char chunk[4];
  char hexchar[1] = "";
  mystring result;
  result.text[0] = '\0';

  for(i = 0; i < source.length; i++)
  {
    if (i > 0 && i % 4 == 0)
    {
      binaryquadtohexchar(chunk, hexchar);
    }
    chunk[i % 4] = source.text[i];
    if (i == source.length-1)
    {
      binaryquadtohexchar(chunk, hexchar);
    }

  }

}

char binaryquadtohexchar(char * source, char * result)
{
  int i;
  char *p = "";
  char * hexchars[][2] = {
    {"0000", "0"},
    {"0001", "1"},
    {"0010", "2"},
    {"0011", "3"},
    {"0100", "4"},
    {"0101", "5"},
    {"0110", "6"},
    {"0111", "7"},
    {"1000", "8"},
    {"1001", "9"},
    {"1010", "a"},
    {"1011", "b"},
    {"1100", "c"},
    {"1101", "d"},
    {"1110", "e"},
    {"1111", "f"},
  };

  for (i = 0; i <= 15; i++)
  {
    if (strcmp(source, hexchars[i][0]) == 0)
    {
      p = hexchars[i][1];
    }
  }

  *result = *p;

}