var CRC = {};

CRC.CRC16 = function (data) {

    var len = data.length;

    if (len > 0) {

        var crc = 0xFFFF;

        for (var i = 0; i < len; i++) {

            crc = (crc ^ (data[i]));

            for (var j = 0; j < 8; j++) {

                crc = (crc & 1) != 0 ? ((crc >> 1) ^ 0xA001) : (crc >> 1);

            }

        }

        var hi = ((crc & 0xFF00) >> 8);  //高位置

        var lo = (crc & 0x00FF);         //低位置

        return [hi, lo];

    }

    return [0, 0];

};

CRC.isArray = function (arr) {

    return Object.prototype.toString.call(arr) === '[object Array]';

};

CRC.ToCRC16 = function (str, isReverse) {

    return CRC.toString(CRC.CRC16(CRC.isArray(str) ? str : CRC.strToByte(str)), isReverse);

};

CRC.ToModbusCRC16 = function (str, isReverse) {

    return CRC.toString(CRC.CRC16(CRC.isArray(str) ? str : CRC.strToHex(str)), isReverse);

};

CRC.strToByte = function (str) {

    var tmp = str.split(''), arr = [];

    for (var i = 0, c = tmp.length; i < c; i++) {

        var j = encodeURI(tmp[i]);

        if (j.length == 1) {

            arr.push(j.charCodeAt());

        } else {

            var b = j.split('%');

            for (var m = 1; m < b.length; m++) {

                arr.push(parseInt('0x' + b[m]));

            }

        }

    }

    return arr;

};

CRC.convertChinese = function (str) {

    var tmp = str.split(''), arr = [];

    for (var i = 0, c = tmp.length; i < c; i++) {

        var s = tmp[i].charCodeAt();

        if (s <= 0 || s >= 127) {

            arr.push(s.toString(16));

        }

        else {

            arr.push(tmp[i]);

        }

    }

    return arr;

};

CRC.filterChinese = function (str) {

    var tmp = str.split(''), arr = [];

    for (var i = 0, c = tmp.length; i < c; i++) {

        var s = tmp[i].charCodeAt();

        if (s > 0 && s < 127) {

            arr.push(tmp[i]);

        }

    }

    return arr;

};

CRC.strToHex = function (hex, isFilterChinese) {

    hex = isFilterChinese ? CRC.filterChinese(hex).join('') : CRC.convertChinese(hex).join('');

    //清除所有空格

    hex = hex.replace(/\s/g, "");

    //若字符个数为奇数，补一个0

    hex += hex.length % 2 != 0 ? "0" : "";

    var c = hex.length / 2, arr = [];

    for (var i = 0; i < c; i++) {

        arr.push(parseInt(hex.substr(i * 2, 2), 16));

    }

    return arr;

};

CRC.padLeft = function (s, w, pc) {

    if (pc == undefined) {

        pc = '0';

    }

    for (var i = 0, c = w - s.length; i < c; i++) {

        s = pc + s;

    }

    return s;

};

CRC.toString = function (arr, isReverse) {

    if (typeof isReverse == 'undefined') {

        isReverse = true;

    }

    var hi = arr[0], lo = arr[1];

    return CRC.padLeft((isReverse ? hi + lo * 0x100 : hi * 0x100 + lo).toString(16).toUpperCase(), 4, '0');

};