如何在php中计算crc16

我需要帮助将用Ojective C编写的CRC代码转换为 PHP.以下是Objective C代码

static UInt16 CRC16_Table[] =
   {    0x0000,0x2110,0x4220,0x6330,0x8440,0xa550,0xc660,0xe770,0x0881,0x2991,0x4aa1,0x6bb1,0x8cc1,0xadd1,0xcee1,0xeff1,0x3112,0x1002,0x7332,0x5222,0xb552,0x9442,0xf772,0xd662,0x3993,0x1883,0x7bb3,0x5aa3,0xbdd3,0x9cc3,0xfff3,0xdee3,0x6224,0x4334,0x2004,0x0114,0xe664,0xc774,0xa444,0x8554,0x6aa5,0x4bb5,0x2885,0x0995,0xeee5,0xcff5,0xacc5,0x8dd5,0x5336,0x7226,0x1116,0x3006,0xd776,0xf666,0x9556,0xb446,0x5bb7,0x7aa7,0x1997,0x3887,0xdff7,0xfee7,0x9dd7,0xbcc7,0xc448,0xe558,0x8668,0xa778,0x4008,0x6118,0x0228,0x2338,0xccc9,0xedd9,0x8ee9,0xaff9,0x4889,0x6999,0x0aa9,0x2bb9,0xf55a,0xd44a,0xb77a,0x966a,0x711a,0x500a,0x333a,0x122a,0xfddb,0xdccb,0xbffb,0x9eeb,0x799b,0x588b,0x3bbb,0x1aab,0xa66c,0x877c,0xe44c,0xc55c,0x222c,0x033c,0x600c,0x411c,0xaeed,0x8ffd,0xeccd,0xcddd,0x2aad,0x0bbd,0x688d,0x499d,0x977e,0xb66e,0xd55e,0xf44e,0x133e,0x322e,0x511e,0x700e,0x9fff,0xbeef,0xdddf,0xfccf,0x1bbf,0x3aaf,0x599f,0x788f,0x8891,0xa981,0xcab1,0xeba1,0x0cd1,0x2dc1,0x4ef1,0x6fe1,0x8010,0xa100,0xc230,0xe320,0x0450,0x2540,0x4670,0x6760,0xb983,0x9893,0xfba3,0xdab3,0x3dc3,0x1cd3,0x7fe3,0x5ef3,0xb102,0x9012,0xf322,0xd232,0x3542,0x1452,0x7762,0x5672,0xeab5,0xcba5,0xa895,0x8985,0x6ef5,0x4fe5,0x2cd5,0x0dc5,0xe234,0xc324,0xa014,0x8104,0x6674,0x4764,0x2454,0x0544,0xdba7,0xfab7,0x9987,0xb897,0x5fe7,0x7ef7,0x1dc7,0x3cd7,0xd326,0xf236,0x9106,0xb016,0x5766,0x7676,0x1546,0x3456,0x4cd9,0x6dc9,0x0ef9,0x2fe9,0xc899,0xe989,0x8ab9,0xaba9,0x4458,0x6548,0x0678,0x2768,0xc018,0xe108,0x8238,0xa328,0x7dcb,0x5cdb,0x3feb,0x1efb,0xf98b,0xd89b,0xbbab,0x9abb,0x754a,0x545a,0x376a,0x167a,0xf10a,0xd01a,0xb32a,0x923a,0x2efd,0x0fed,0x6cdd,0x4dcd,0xaabd,0x8bad,0xe89d,0xc98d,0x267c,0x076c,0x645c,0x454c,0xa23c,0x832c,0xe01c,0xc10c,0x1fef,0x3eff,0x5dcf,0x7cdf,0x9baf,0xbabf,0xd98f,0xf89f,0x176e,0x367e,0x554e,0x745e,0x932e,0xb23e,0xd10e,0xf01e
   };


   +(SInt16) CalculateCRC16 : (Byte*)buffer : (UInt16) length
   {
    UInt32   crc=0;

    while (length--)
        crc = ((crc>>8) & 0xff) ^ *(CRC16_Table + ((*buffer++ ^ crc) & 0xff));

    return((SInt16)crc);
   }

以下是我到目前为止在PHP中编写的代码

$CRC16_Table = array
        (   0x0000,0xf01e
        );

   function CalculateCRC16($strMessage)
   {
      $hexdata = pack('H*',$strMessage);
        $nLength = strlen($hexdata);
        $crc = 0xFFFF;
        $pos = 0;
        while($nLength > 0)
        {
            $crc = ($crc >> 8) ^ $CRC16_Table[($crc ^ ord($hexdata[$pos])) &       0xFF];
            $nLength--;
            $pos++;
        }
        return ~$crc;
   }

其中$strMessage包含打包值,但它没有给出正确的结果.

任何帮助将受到高度赞赏.

这似乎有效,使用针对CRC-16-CCITT的 this website的几个值进行测试

请注意,它使用PHP字符串作为直接字节缓冲区,因为它的PHP最接近于byte []

<?PHP

class CRC16 {
    private static $CRC16_Table = array
        (   0x0000,0xf01e
        );

    public static function calculate( $buffer ) {
        $length = strlen($buffer);

        $crc = 0;
        $i = 0;
        while( $length-- ) {
            $crc = (( $crc >> 8) & 0xff) ^ (self::$CRC16_Table[(ord($buffer[$i++]) ^ $crc) & 0xFF]);
        }

        return (($crc & 0xFFFF) ^ 0x8000) - 0x8000;
    }    
}

echo CRC16::calculate( "\x74\x65\x73\x74" );

如何在php中计算crc16

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