// 异或和校验
function xor_verify(data){
    if (data.length < 2){
        return false;
    }
    var xor_sum = xor(data, 1, data.length - 2);
    if (xor_sum == data[data.length - 1]){
        return true;
    }
    return false;
}
// 获取异或和
function xor(data, start, end){
    var xor_sum = data[start];
    for (var i = start + 1; i < end + 1; i++){
        xor_sum ^= data[i];
    }
    return xor_sum;
}
// crc校验
function crc(bytes) {
    // CRC寄存器全为1
    var CRC = 0x0000ffff;
    // 多项式校验值
    var POLYNOMIAL = 0x0000a001;
    for (var i = 0; i < bytes.length; i++) {
        CRC ^= bytes[i] & 0x000000ff;
        for (var j = 0; j < 8; j++) {
            if (CRC & 0x00000001 != 0) {
                CRC >>= 1;
                CRC ^= POLYNOMIAL;
            } else {
                CRC >>= 1;
            }
        }
    }
    return CRC;
}

function crc_verify(data){
    var verifyBytes = ConvertToUint8Array(data, 1, data.length - 2);
    var crcBytes = ConvertToUint8Array(data, data.length - 2, data.length);
    var thisCrc = crc(verifyBytes);
    var thatCrc = new DataView(crcBytes.buffer).getUint16(0, true);
    if (thisCrc == thatCrc){
        return true;
    }
    return false;
}
// 字节数组
function ArrayToHexString(data,start,end){
    start = start?start:0;
    end = end?end:data.length;
    var Hex = '';
    for (var i =start; i < end; i++) {
        var s = data[i].toString(16);
        if (s.length == 1) {
            s = "0"+s;
        }
        Hex += s;
    }
    return Hex.toUpperCase();
}
function ConvertToUint8Array(rawData, start, end) {
    start = start?start:0;
    end = end?end:rawData.length;
    var uint8Array = new Uint8Array(end - start);
    for (var i = start; i < end; i++) {
        uint8Array[i-start] = rawData[i] & 0xff;
    }
    return uint8Array;
}
// 合并字节数组
function concat(array1, array2) {
    var uint8Array = new Uint8Array(array1.length + array2.length);
    for (var i = 0; i < array1.length; i++) {
        uint8Array[i] = array1[i] & 0xff;
    }
    for (var j = 0; j < array2.length; j++) {
        uint8Array[j + array1.length] = array2[j] & 0xff;
    }
    return uint8Array;
}
// 判断数组中是否包含某个元素
function includes(array, item) {
    for (var i = 0; i < array.length; i++){
        if (array[i] == item){
            return true;
        }
    }
    return false;
}