Question

我需要一个能够生成Maxim / Dallas 1-Wire CRC 8位代码的功能，如下页所示： http://www.datastat.com/sysadminjournal/maximcrc.cgi

对于那个问题，我找到了一个小的Excel计算器来解决问题。它工作正常，但我有问题将其翻译成PHP语言。

原始VB代码：

Private Sub ROMCRC_Click()

    Dim InHex, OutBinStr As String
    Dim OutBinArr(1 To 56) As Integer
    Dim OutDec, i, CRC(1 To 8), CRCTemp As Integer

    InHex = Range("ROMByte1").Value & Range("ROMByte2").Value & Range("ROMByte3").Value & Range("ROMByte4").Value & Range("ROMByte5").Value & Range("ROMByte6").Value & Range("ROMByte7").Value
    OutBinStr = HexToBin(InHex)

    ' Convert string to array, LSB = OutBinArr(1)
    For i = 1 To 56
    OutBinArr(57 - i) = Mid$(OutBinStr, i, 1) ' Split(OutBinStr)
    Next i

    'Initialize CRC
    For i = 1 To 8
        CRC(i) = 0
    Next i

    'Calculate CRC
    For i = 1 To 56
        CRCTemp = CRC(1) Xor OutBinArr(i)
        CRC(1) = CRC(2)
        CRC(2) = CRC(3)
        CRC(3) = CRC(4) Xor CRCTemp
        CRC(4) = CRC(5) Xor CRCTemp
        CRC(5) = CRC(6)
        CRC(6) = CRC(7)
        CRC(7) = CRC(8)
        CRC(8) = CRCTemp
    Next i

    DecCRC = BinToDec(CRC)

    Range("ROMCRCValue").Value = DecCRC

End Sub


Private Function HexToBin(hstr)
'convert hex string to binary string
    cnvarr = Array("0000", "0001", "0010", "0011", _
             "0100", "0101", "0110", "0111", "1000", _
             "1001", "1010", "1011", "1100", "1101", _
             "1110", "1111")
    bstr = ""
    For i = 1 To Len(hstr)
        hdgt = Mid(hstr, i, 1)
        cix = CInt("&H" & hdgt)
        bstr = bstr & cnvarr(cix)
    Next
    HexToBin = bstr
End Function

Function BinToDec(bstr)
'convert 8 bit Binary number to Decimal
    Dim j, Out As Integer

    Out = 0
    For j = 1 To 8
        Out = Out + bstr(j) * 2 ^ (j - 1)
    Next j

    BinToDec = Out
End Function

我的PHP测试代码：

protected function HexToBin($hstr) {
    //convert hex string to binary string
    $cnvarr = array(
        '0000',
        '0001',
        '0010',
        '0011',
        '0100',
        '0101',
        '0110',
        '0111',
        '1000',
        '1001',
        '1010',
        '1011',
        '1100',
        '1101',
        '1110',
        '1111'
    );
    $bstr = "";
    for ($i = 1; $i <= strlen($hstr); $i++) {
        $hdgt = substr($hstr, $i, 1);
        $cix = intval($hdgt);
        echo $cix.'|';
        $bstr .= $cnvarr[$cix];
    }
    return $bstr;
}

protected function createHash($data) {
    //$OutBinStr = $this->HexToBin($data);
    $OutBinStr = hex2bin($data);

    $OutBinArr = array();
    $crc = array();

    //Convert string to array, LSB = OutBinArr(1)
    for ($i = 1; $i <= 56; $i++) {
        $OutBinArr[57 - $i] = substr($OutBinStr, $i - 1, 1);
    }

    //initialize crc
    for ($i = 1; $i <= 8; $i++) {
        $crc[$i] = 0;
    }

    // calculate
    for ($i = 1; $i <= 56; $i++) {

        $CRCTemp = $crc[1] ^ $OutBinArr[$i];
        $crc[1] = $crc[2];
        $crc[2] = $crc[3];
        $crc[3] = $crc[4] ^ $CRCTemp;
        $crc[4] = $crc[5] ^ $CRCTemp;
        $crc[5] = $crc[6];
        $crc[6] = $crc[7];
        $crc[7] = $crc[8];
        $crc[8] = $CRCTemp;
    }

    return implode('', $crc);
}

示例电话：

$buttonId = '0000145D6E0F01';
echo $this->createHash($buttonId);

如果您有任何想法，为什么脚本无法生成正确的crc，我感谢您。

谢谢你，很高兴迈克尔

Answer 1

您的HexToBin()生成了错误的字符串。 for的{{1}}循环以1而不是0开头。请参阅substr manual。

Imploding $ crc导致反向位序值。

substr()

CRC Maxim / Dallas 1Wire Generation：将Visual Basic转换为PHP

1 个答案: