function decodeMessage()

in content/lib/paho-mqtt.js [459:537]
65 lines of code
16 McCabe index (conditional complexity)

	function decodeMessage(input,pos) {
	    var startingPos = pos;
		var first = input[pos];
		var type = first >> 4;
		var messageInfo = first &= 0x0f;
		pos += 1;


		// Decode the remaining length (MBI format)

		var digit;
		var remLength = 0;
		var multiplier = 1;
		do {
			if (pos == input.length) {
			    return [null,startingPos];
			}
			digit = input[pos++];
			remLength += ((digit & 0x7F) * multiplier);
			multiplier *= 128;
		} while ((digit & 0x80) !== 0);

		var endPos = pos+remLength;
		if (endPos > input.length) {
		    return [null,startingPos];
		}

		var wireMessage = new WireMessage(type);
		switch(type) {
			case MESSAGE_TYPE.CONNACK:
				var connectAcknowledgeFlags = input[pos++];
				if (connectAcknowledgeFlags & 0x01)
					wireMessage.sessionPresent = true;
				wireMessage.returnCode = input[pos++];
				break;

			case MESSAGE_TYPE.PUBLISH:
				var qos = (messageInfo >> 1) & 0x03;

				var len = readUint16(input, pos);
				pos += 2;
				var topicName = parseUTF8(input, pos, len);
				pos += len;
				// If QoS 1 or 2 there will be a messageIdentifier
				if (qos > 0) {
					wireMessage.messageIdentifier = readUint16(input, pos);
					pos += 2;
				}

				var message = new Paho.MQTT.Message(input.subarray(pos, endPos));
				if ((messageInfo & 0x01) == 0x01)
					message.retained = true;
				if ((messageInfo & 0x08) == 0x08)
					message.duplicate =  true;
				message.qos = qos;
				message.destinationName = topicName;
				wireMessage.payloadMessage = message;
				break;

			case  MESSAGE_TYPE.PUBACK:
			case  MESSAGE_TYPE.PUBREC:
			case  MESSAGE_TYPE.PUBREL:
			case  MESSAGE_TYPE.PUBCOMP:
			case  MESSAGE_TYPE.UNSUBACK:
				wireMessage.messageIdentifier = readUint16(input, pos);
				break;

			case  MESSAGE_TYPE.SUBACK:
				wireMessage.messageIdentifier = readUint16(input, pos);
				pos += 2;
				wireMessage.returnCode = input.subarray(pos, endPos);
				break;

			default:
				break;
		}

		return [wireMessage,endPos];
	}