在 Google Apps 脚本中计算 CRC16 CCITT FALSE [重复]

Question

我有计算字符串的 CRC16 CCITT 值的 VBA 代码，但现在我计划在 Google Sheet 上使用它，但不知道它将如何在 google 脚本上使用

Function crc_ccitt_ffff(strParam As String) As String
  Const CRC_POLY_CCITT       As Long = &H1021&
  Const CRC_START_CCITT_FFFF As Long = &HFFFF&

  Dim crc_tabccitt(0 To 255) As Long, crc As Long, b() As Byte, c As Long, i As Long, j As Long
                                                                          
                                                                         
  For i = 0 To 255
      crc = 0
      c = i * 256
      For j = 0 To 7
          If (crc Xor c) And 32768 Then
             crc = (crc * 2) Xor CRC_POLY_CCITT
          Else
             crc = crc * 2
          End If
          c = c * 2
          Next j
      crc_tabccitt(i) = crc
  Next i
                                                                          
  b = strParam
  crc = CRC_START_CCITT_FFFF
  For i = 0 To UBound(b) Step 2
      crc = (crc * 256) Xor crc_tabccitt(((crc \ 256) Xor b(i)) And 255)
      crc = ((crc \ 65536) * 65536) Xor crc
  Next i
  crc_ccitt_ffff = Hex(crc)
End Function

A 列上的字符串：00020101021129370016A000000677010111021312345678901215802TH5406500.5553037646304

B 列（或任何其他列）的预期结果：3D85

谁能帮我解决这个问题？

Answer 1

好的。只是为了好玩，我设法将您的 VB 代码（不确定代码是否有效）翻译成 JS。给你：

function crc_ccitt_ffff(str) {
    const POLY  = 0x1021;
    const START = 0xFFFF;

    function get_crc_for_num(i) {
        var crc = 0;
        var c = i * 256;
        [...Array(8).keys()].forEach(_ => {
            crc = ((crc ^ c) & 0x8000) ? (crc * 2) ^ POLY : crc * 2;
            c = c * 2 });
        return crc;
    }

    var table = [...Array(256).keys()].map((_,n) => get_crc_for_num(n));

    var crc = START;

    str.split('').forEach(c => {
        crc = (crc * 0x100) ^ table[ ( ((crc / 0x100) >> 0) ^ c.charCodeAt() ) & 0xFF ];
        crc = (((crc / 0x10000) >> 0) * 0x10000) ^ crc;
        }
    )

    return crc.toString(16);
}

var str = '00020101021129370016A000000677010111021312345678901215802TH5406500.5553037646304';

console.log( crc_ccitt_ffff(str) ); // output 3d85

它与您的数据给出相同的结果，它给出的结果与此处https://crccalc.com/ 相同

但是，请注意，我不是真正的编码员，我对 VB 和 CRC-16 几乎一无所知。因此，在将代码投入生产之前彻底测试我的代码是有意义的。

---

这是 Google 电子表格的代码：

function main() {
  const sheet = SpreadsheetApp.getActiveSheet();
  const range = sheet.getRange("A1:B");
  const data = range.getValues().map(x => [x[0], crc_ccitt_ffff(x[0])]);
  range.setValues(data);
}

function crc_ccitt_ffff(str) {
  if (str == '') return;

  const get_crc_for_num = (n) => {
    let crc = 0;
    let c = n * 256;
    [...Array(8).keys()].forEach(_ => {
      crc = ((crc ^ c) & 0x8000) ? (crc * 2) ^ 0x1021 : crc * 2;
      c = c * 2;
    });
    return crc;
  }

  const table = [...Array(256).keys()].map((_,n) => get_crc_for_num(n));

  var crc = 0xFFFF;

  str.split('').forEach(c => {
    crc = (crc * 0x100) ^ table[(((crc / 0x100) >> 0) ^ c.charCodeAt()) & 0xFF];
    crc = (((crc / 0x10000) >> 0) * 0x10000) ^ crc; 
  });

  return crc.toString(16);
}

它从“A”列获取所有字符串，并将它们的 CRC-16 放入“B”列。

Answer 2

不确定我的解决方案是否正确。这里是CRC-16/CCITT的JS实现：Generate CRC16 CCITT False with Javascript?

它给出的7D133D85 看起来很像您的预期结果。我不知道 VB 代码中的前四位数字在哪里。

所以我采用了那个 JS 代码并以这种方式对其进行了一点更新：

var crcTable = [
    0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7,
    0x8108, 0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF,
    0x1231, 0x0210, 0x3273, 0x2252, 0x52B5, 0x4294, 0x72F7, 0x62D6,
    0x9339, 0x8318, 0xB37B, 0xA35A, 0xD3BD, 0xC39C, 0xF3FF, 0xE3DE,
    0x2462, 0x3443, 0x0420, 0x1401, 0x64E6, 0x74C7, 0x44A4, 0x5485,
    0xA56A, 0xB54B, 0x8528, 0x9509, 0xE5EE, 0xF5CF, 0xC5AC, 0xD58D,
    0x3653, 0x2672, 0x1611, 0x0630, 0x76D7, 0x66F6, 0x5695, 0x46B4,
    0xB75B, 0xA77A, 0x9719, 0x8738, 0xF7DF, 0xE7FE, 0xD79D, 0xC7BC,
    0x48C4, 0x58E5, 0x6886, 0x78A7, 0x0840, 0x1861, 0x2802, 0x3823,
    0xC9CC, 0xD9ED, 0xE98E, 0xF9AF, 0x8948, 0x9969, 0xA90A, 0xB92B,
    0x5AF5, 0x4AD4, 0x7AB7, 0x6A96, 0x1A71, 0x0A50, 0x3A33, 0x2A12,
    0xDBFD, 0xCBDC, 0xFBBF, 0xEB9E, 0x9B79, 0x8B58, 0xBB3B, 0xAB1A,
    0x6CA6, 0x7C87, 0x4CE4, 0x5CC5, 0x2C22, 0x3C03, 0x0C60, 0x1C41,
    0xEDAE, 0xFD8F, 0xCDEC, 0xDDCD, 0xAD2A, 0xBD0B, 0x8D68, 0x9D49,
    0x7E97, 0x6EB6, 0x5ED5, 0x4EF4, 0x3E13, 0x2E32, 0x1E51, 0x0E70,
    0xFF9F, 0xEFBE, 0xDFDD, 0xCFFC, 0xBF1B, 0xAF3A, 0x9F59, 0x8F78,
    0x9188, 0x81A9, 0xB1CA, 0xA1EB, 0xD10C, 0xC12D, 0xF14E, 0xE16F,
    0x1080, 0x00A1, 0x30C2, 0x20E3, 0x5004, 0x4025, 0x7046, 0x6067,
    0x83B9, 0x9398, 0xA3FB, 0xB3DA, 0xC33D, 0xD31C, 0xE37F, 0xF35E,
    0x02B1, 0x1290, 0x22F3, 0x32D2, 0x4235, 0x5214, 0x6277, 0x7256,
    0xB5EA, 0xA5CB, 0x95A8, 0x8589, 0xF56E, 0xE54F, 0xD52C, 0xC50D,
    0x34E2, 0x24C3, 0x14A0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
    0xA7DB, 0xB7FA, 0x8799, 0x97B8, 0xE75F, 0xF77E, 0xC71D, 0xD73C,
    0x26D3, 0x36F2, 0x0691, 0x16B0, 0x6657, 0x7676, 0x4615, 0x5634,
    0xD94C, 0xC96D, 0xF90E, 0xE92F, 0x99C8, 0x89E9, 0xB98A, 0xA9AB,
    0x5844, 0x4865, 0x7806, 0x6827, 0x18C0, 0x08E1, 0x3882, 0x28A3,
    0xCB7D, 0xDB5C, 0xEB3F, 0xFB1E, 0x8BF9, 0x9BD8, 0xABBB, 0xBB9A,
    0x4A75, 0x5A54, 0x6A37, 0x7A16, 0x0AF1, 0x1AD0, 0x2AB3, 0x3A92,
    0xFD2E, 0xED0F, 0xDD6C, 0xCD4D, 0xBDAA, 0xAD8B, 0x9DE8, 0x8DC9,
    0x7C26, 0x6C07, 0x5C64, 0x4C45, 0x3CA2, 0x2C83, 0x1CE0, 0x0CC1,
    0xEF1F, 0xFF3E, 0xCF5D, 0xDF7C, 0xAF9B, 0xBFBA, 0x8FD9, 0x9FF8,
    0x6E17, 0x7E36, 0x4E55, 0x5E74, 0x2E93, 0x3EB2, 0x0ED1, 0x1EF0,
];

function crc16(str) {
    var crc = 0xFFFF;

    str.split('').forEach(c => 
        crc = (crc << 8) ^ crcTable[(c.charCodeAt(0) ^ (crc >> 8)) & 0xFF]);

    return crc.toString(16).toUpperCase();
}

var str = "00020101021129370016A000000677010111021312345678901215802TH5406500.5553037646304"

console.log(crc16(str));              // it gives 7d133d85
console.log(crc16(str).substring(4)); // it gives 3d85

如您所见，我使用substring(4) 去掉了前四位数字。可能这是一个愚蠢的想法。坦率地说，我不确定这个技巧是否适用。你必须在你的数据上尝试一下。

或者等待有人能准确地将你的VB代码翻译成JS。这看起来不是一个无法解决的任务。