JavaScript Intel Hex Parser For BlueGiga BLE Device Updates

intel-hex-parser.js

var fs = require('fs');

function parseIntelHexData(path, callback) {
  var hex = fs.readFileSync(path).toString();

  console.log('loaded file');
  // Split the file into lines
  var hexLines = hex.split('\n');
  // The last line is an empty string
  hexLines.pop();

  // initialize the buffer as large as it could be (to save time)
  var buff = new Buffer(hexLines.length * 16);
  
  // Start at 0
  var buffPos = 0;
  
  // Don't store data until we're at the right line
  var startRecording = false;
  
  // This start address is specific to BLE. Most people won't need it.
  var startAddress = parseInt('0x1000', 16);
 
  // For each line
  for (var i = 0; i < hexLines.length; i++) {
    // Grab the line
    var line = hexLines[i];
    // Save the bytecount
    var byteCount = parseInt(line.substr(1, 2), 16);
    // Save the address
    var address = parseInt(line.substr(3, 4), 16);
    // Save the record type
    var recordType = parseInt(line.substr(7, 2), 16);

    // If we hit the start line
    if (address == startAddress) {
      // Start recording
      startRecording = true;
    }
  
    // If we are recording and this is a data record and there are data bytes
    if (startRecording && recordType == 0 && byteCount) {

      // First data byte is at byte 9
      var startIndex = 9;
      // For each byte
      for (var j = 0; j < byteCount; j++) {
        // Get the index of the next byte
        var dataIndex = startIndex + (j * 2);
        // Interpret two characters as a hex digit
        buff.writeUInt8(parseInt(line.substr(dataIndex, 2), 16), buffPos);
        // Increase our buffer position
        buffPos++;
      }
    }
  }

  // Cut off any extra bytes (lines that didn't have data)
  buff = buff.slice(0, buffPos);

  console.log("Finished!", buff.length);

  return buff;
}

module.exports = parseIntelHexData;