source: vendor/3.5.10/source3/script/gap.awk

BEGIN { hv["0"] =  0; hv["1"] =  1; hv["2"] =  2; hv["3"] =  3;
        hv["4"] =  4; hv["5"] =  5; hv["6"] =  6; hv["7"] =  7;
        hv["8"] =  8; hv["9"] =  9; hv["A"] = 10; hv["B"] = 11;
        hv["C"] = 12; hv["D"] = 13; hv["E"] = 14; hv["F"] = 15;
        hv["a"] = 10; hv["b"] = 11; hv["c"] = 12; hv["d"] = 13;
        hv["e"] = 14; hv["f"] = 15;

        first = 0; last = 0; idx = 0;
}

function tonum(str)
{
  num=0;
  cnt=1;
  while (cnt <= length(str)) {
    num *= 16;
    num += hv[substr(str,cnt,1)];
    ++cnt;
  }
  return num;
}

{
  u = tonum($1);
  if (u - last > 6)
    {
      if (last)
        {
          printf ("  { 0x%04x, 0x%04x, %5d },\n",
                  first, last, idx);
          idx -= u - last - 1;
        }
      first = u;
    }
  last = u;
}

END { printf ("  { 0x%04x, 0x%04x, %5d },\n",
              first, last, idx); }