crc crc16 xmodem modbus 循环冗余校验 js 实现

背景：在做一个第功耗蓝牙的项目，用到了crc校验、分包发送

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CRC-16/XMODEM 校验
都是传入16进制的字符串,方便看到 如：'FF2233FF'

/** 将hex转换为 CRC-16/XMODEM 校验 
 * 
 * 参数长度需要被2整除
 * 
 * 第八位在前，高八位在后
 */
export const crc16xmodem = (datass) => {
    return CRC_16_XMODEM(Str2Bytes(datass), datass.length / 2)
}

const Str2Bytes = (str) => {
    var pos = 0;
    var len = str.length;
    if (len % 2 != 0) {
      return null;
    }
    len /= 2;
    var hexA = new Array();
    for (var i = 0; i < len; i++) {
      var s = str.substr(pos, 2);
      var v = parseInt(s, 16);
      hexA.push(v);
      pos += 2;
    }
    return hexA;
  }

  function CRC_16_XMODEM(bytes, length) {
    let crc = 0x0000;
    let polynomial = 0x1021;
    for (let index = 0; index < length; index++) {
      let b = bytes[index];
      for (let i = 0; i < 8; i++) {
        let bit = ((b >> (7 - i) & 1) == 1);
        let c15 = ((crc >> 15 & 1) == 1);
        crc <<= 1;
        if (c15 ^ bit)
          crc ^= polynomial;
      }
    }
    crc &= 0xffff;
    // 输出String字样的16进制
    let strCrc = crc.toString(16).toLocaleUpperCase();
    switch (strCrc.length) {
      case 1:
        strCrc = "000" + strCrc;
        break;
      case 2:
        strCrc = "00" + strCrc;
        break;
      case 3:
        strCrc = "0" + strCrc;
        break;
      case 4:
        strCrc = strCrc
        break;
      default:
        break;
    }
    strCrc = strCrc[2] + strCrc[3] + strCrc[0] + strCrc[1]
    return strCrc;

  }

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CRC-16/MODBUS 查表法

使用：const crcData = CRC.ToModbusCRC16('FF2233FF')

var CRC = {};

CRC._auchCRCHi = [
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
    0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
    0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
    0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
    0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40,
    0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
    0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40,
    0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
    0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
    0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
    0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40,
    0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
    0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40
];
CRC._auchCRCLo = [
    0x00, 0xC0, 0xC1, 0x01, 0xC3, 0x03, 0x02, 0xC2, 0xC6, 0x06,
    0x07, 0xC7, 0x05, 0xC5, 0xC4, 0x04, 0xCC, 0x0C, 0x0D, 0xCD,
    0x0F, 0xCF, 0xCE, 0x0E, 0x0A, 0xCA, 0xCB, 0x0B, 0xC9, 0x09,
    0x08, 0xC8, 0xD8, 0x18, 0x19, 0xD9, 0x1B, 0xDB, 0xDA, 0x1A,
    0x1E, 0xDE, 0xDF, 0x1F, 0xDD, 0x1D, 0x1C, 0xDC, 0x14, 0xD4,
    0xD5, 0x15, 0xD7, 0x17, 0x16, 0xD6, 0xD2, 0x12, 0x13, 0xD3,
    0x11, 0xD1, 0xD0, 0x10, 0xF0, 0x30, 0x31, 0xF1, 0x33, 0xF3,
    0xF2, 0x32, 0x36, 0xF6, 0xF7, 0x37, 0xF5, 0x35, 0x34, 0xF4,
    0x3C, 0xFC, 0xFD, 0x3D, 0xFF, 0x3F, 0x3E, 0xFE, 0xFA, 0x3A,
    0x3B, 0xFB, 0x39, 0xF9, 0xF8, 0x38, 0x28, 0xE8, 0xE9, 0x29,
    0xEB, 0x2B, 0x2A, 0xEA, 0xEE, 0x2E, 0x2F, 0xEF, 0x2D, 0xED,
    0xEC, 0x2C, 0xE4, 0x24, 0x25, 0xE5, 0x27, 0xE7, 0xE6, 0x26,
    0x22, 0xE2, 0xE3, 0x23, 0xE1, 0x21, 0x20, 0xE0, 0xA0, 0x60,
    0x61, 0xA1, 0x63, 0xA3, 0xA2, 0x62, 0x66, 0xA6, 0xA7, 0x67,
    0xA5, 0x65, 0x64, 0xA4, 0x6C, 0xAC, 0xAD, 0x6D, 0xAF, 0x6F,
    0x6E, 0xAE, 0xAA, 0x6A, 0x6B, 0xAB, 0x69, 0xA9, 0xA8, 0x68,
    0x78, 0xB8, 0xB9, 0x79, 0xBB, 0x7B, 0x7A, 0xBA, 0xBE, 0x7E,
    0x7F, 0xBF, 0x7D, 0xBD, 0xBC, 0x7C, 0xB4, 0x74, 0x75, 0xB5,
    0x77, 0xB7, 0xB6, 0x76, 0x72, 0xB2, 0xB3, 0x73, 0xB1, 0x71,
    0x70, 0xB0, 0x50, 0x90, 0x91, 0x51, 0x93, 0x53, 0x52, 0x92,
    0x96, 0x56, 0x57, 0x97, 0x55, 0x95, 0x94, 0x54, 0x9C, 0x5C,
    0x5D, 0x9D, 0x5F, 0x9F, 0x9E, 0x5E, 0x5A, 0x9A, 0x9B, 0x5B,
    0x99, 0x59, 0x58, 0x98, 0x88, 0x48, 0x49, 0x89, 0x4B, 0x8B,
    0x8A, 0x4A, 0x4E, 0x8E, 0x8F, 0x4F, 0x8D, 0x4D, 0x4C, 0x8C,
    0x44, 0x84, 0x85, 0x45, 0x87, 0x47, 0x46, 0x86, 0x82, 0x42,
    0x43, 0x83, 0x41, 0x81, 0x80, 0x40
];

CRC.CRC16 = function (buffer) {
    var hi = 0xff;
    var lo = 0xff;
    for (var i = 0; i < buffer.length; i++) {
        var idx = hi ^ buffer[i];
        hi = (lo ^ CRC._auchCRCHi[idx]);
        lo = CRC._auchCRCLo[idx];
    }

    return CRC.padLeft((hi << 8 | lo ).toString(16).toUpperCase(), 4, '0');
};

CRC.isArray = function (arr) {
    return Object.prototype.toString.call(arr) === '[object Array]';
};

CRC.ToCRC16 = function (str) {
    return CRC.CRC16(CRC.isArray(str) ? str : CRC.strToByte(str));
};

CRC.ToModbusCRC16 = function (str) {
    return CRC.CRC16(CRC.isArray(str) ? str : CRC.strToHex(str));
};

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，补一个空格
    hex += hex.length % 2 != 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;
};