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/**
 * Parser for Lobaro Pressure Probe via LoRaWAN (hybrid gateway).
 * Usable for Pressure Probe as or with Presure+Temperature Probe.
 * Works with TTN, ChirpStack, or the Lobaro Platform.
 */
function signed(val, bits) {
    // max positive value possible for signed int with bits:
    var mx = Math.pow(2, bits-1);
    if (val < mx) {
        // is positive value, just return
        return val;
    } else {
        // is negative value, convert to neg:
        return val - (2 * mx);
    }
}
function int16_BE(bytes, idx) {
    bytes = bytes.slice(idx || 0);
    return signed(bytes[0] << 8 | bytes[1] << 0, 2*8);
}
function uint16_BE(bytes, idx) {
    bytes = bytes.slice(idx || 0);
    return bytes[0] << 8 | bytes[1] << 0;
}
function uint32_BE(bytes, idx) {
    bytes = bytes.slice(idx || 0);
    return bytes[0] << 24 | bytes[1] << 16 | bytes[2] << 8 | bytes[3] << 0;
}
function float32FromInt(asInt) {
    var sign = (asInt & 0x80000000) ? -1 : 1;
    var exponent = ((asInt >> 23) & 0xFF) - 127;
    var significand = (asInt & ~(-1 << 23));
    if (exponent === 128)
        return null;
        // return sign * ((significand) ? Number.NaN : Number.POSITIVE_INFINITY);
    if (exponent === -127) {
        if (significand === 0) return sign * 0.0;
        exponent = -126;
        significand /= (1 << 22);
    } else significand = (significand | (1 << 23)) / (1 << 23);
    return sign * significand * Math.pow(2, exponent);
}
function float32_BE(bytes, idx) { return float32FromInt(uint32_BE(bytes, idx)); }
 
/**
 * TTN decoder function.
 */
function Decoder(bytes, port) {
    var vals = {};
    if( port == 20 ){
        if (bytes.length==5) {
          // Pressure Probe without temperature sensor and Bridges internal Temperature
          vals["error"] = !!(bytes[0]&0x80);
          vals["pressure"] = int16_BE(bytes, 1)/1000;
          vals["temperature"] = int16_BE(bytes, 3);
        }  else if (bytes.length==7) {
          vals["error"] = !!(bytes[0]&0x80);
          vals["pressure"] = int16_BE(bytes, 1)/1000;
          vals["temperature"] = int16_BE(bytes, 3);
          vals["voltage"] = uint16_BE(bytes, 5) / 1000;
        } else if (bytes.length==9) {
          vals["error"] = !!(bytes[0]&0x80);
          // pressure in mH2O
          vals["pressure"] = float32_BE(bytes, 1);
          // temperature in Degree Celsius
          vals["temperature"] = float32_BE(bytes, 5);
        } else if (bytes.length==11) {
          vals["error"] = !!(bytes[0]&0x80);
          // pressure in mH2O
          vals["pressure"] = float32_BE(bytes, 1);
          // temperature in Degree Celsius
          vals["temperature"] = float32_BE(bytes, 5);
              vals["voltage"] = uint16_BE(bytes, 9) / 1000;
        }
         
    }
    
    if (port === 64 && bytes.length == 13) { // status packet
        vals["Firmware Identifier"] =  String.fromCharCode(bytes[0]) + String.fromCharCode(bytes[1]) + String.fromCharCode(bytes[2]);
        vals["FirmwareVersion"] = bytes[3] + '.' + bytes[4] + '.' + bytes[5]; 
        vals["status"] = bytes[6]; 
        vals["reboot reason"] = bytes[7];
        vals["final words"] = bytes[8];
        vals["voltage [V]"] = uint16_BE(bytes,9)/1000.0
        vals["temperature [°C]"] =  int16_BE(bytes,11)/10.0;
    } 
    return vals;
}
  
/**
 * TTN V3 Wrapper
 */
function decodeUplink(input) {
   return {
    data: {
      values: Decoder(input.bytes, input.fPort)
    },
    warnings: [],
    errors: []
  };
}
  
/**
 * ChirpStack decoder function.
 */
function Decode(fPort, bytes) {
    // wrap TTN Decoder:
    return Decoder(bytes, fPort);
}
  
/**
 * Lobaro Platform decoder function.
 */
function Parse(input) {
    var data = bytes(atob(input.data));
    var port = input.fPort;
    return Decoder(data, port);
}