gistfile1.txt

var fs = require("fs");

var ws = fs.createWriteStream("0xbfc40000-0xbffffff0-scaled.log");
var rs = fs.createReadStream("0xbfc40000-0xbffffff0.log");

var line = 0;

function tohex(n) {
  var out = n.toString(16);
  return out;
}

rs.on("error", console.log.bind(console));
rs.on("data", function(data) {
  line += 16;
  ws.write(data.toString().replace(/......../, tohex(line)));
});

rs.on("end", function() {
  console.log(line);
  ws.end();
});