unit   CRCUnit;
    
  interface   
  uses   
      Windows,SysUtils;   
  type   
      PBYTE   =^Byte;   

      //計算CRC檢驗碼   
      function   Get_CRC16(const   pData:Pointer;nLength:Integer):string;   
      //檢驗函數   
      function   Check_CRC16(const   pData:Pointer;nLength:Integer):Boolean;   
      //獲取指定字符串的CRC驗證碼   
      function   Get_CRC16Code(strValue   :   string)   :   string;   
    
  const   
      //16位的CRC檢驗表   
      CRCTable16   :   array[0..255]   of   Word   =   (   
          $0000,   $1189,   $2312,   $329b,   $4624,   $57ad,   $6536,   $74bf,   
          $8c48,   $9dc1,   $af5a,   $bed3,   $ca6c,   $dbe5,   $e97e,   $f8f7,   
          $1081,   $0108,   $3393,   $221a,   $56a5,   $472c,   $75b7,   $643e,   
          $9cc9,   $8d40,   $bfdb,   $ae52,   $daed,   $cb64,   $f9ff,   $e876,   
          $2102,   $308b,   $0210,   $1399,   $6726,   $76af,   $4434,   $55bd,   
          $ad4a,   $bcc3,   $8e58,   $9fd1,   $eb6e,   $fae7,   $c87c,   $d9f5,   
          $3183,   $200a,   $1291,   $0318,   $77a7,   $662e,   $54b5,   $453c,   
          $bdcb,   $ac42,   $9ed9,   $8f50,   $fbef,   $ea66,   $d8fd,   $c974,   
          $4204,   $538d,   $6116,   $709f,   $0420,   $15a9,   $2732,   $36bb,   
          $ce4c,   $dfc5,   $ed5e,   $fcd7,   $8868,   $99e1,   $ab7a,   $baf3,   
          $5285,   $430c,   $7197,   $601e,   $14a1,   $0528,   $37b3,   $263a,   
          $decd,   $cf44,   $fddf,   $ec56,   $98e9,   $8960,   $bbfb,   $aa72,   
          $6306,   $728f,   $4014,   $519d,   $2522,   $34ab,   $0630,   $17b9,   
          $ef4e,   $fec7,   $cc5c,   $ddd5,   $a96a,   $b8e3,   $8a78,   $9bf1,   
          $7387,   $620e,   $5095,   $411c,   $35a3,   $242a,   $16b1,   $0738,   
          $ffcf,   $ee46,   $dcdd,   $cd54,   $b9eb,   $a862,   $9af9,   $8b70,   
          $8408,   $9581,   $a71a,   $b693,   $c22c,   $d3a5,   $e13e,   $f0b7,   
          $0840,   $19c9,   $2b52,   $3adb,   $4e64,   $5fed,   $6d76,   $7cff,   
          $9489,   $8500,   $b79b,   $a612,   $d2ad,   $c324,   $f1bf,   $e036,   
          $18c1,   $0948,   $3bd3,   $2a5a,   $5ee5,   $4f6c,   $7df7,   $6c7e,   
          $a50a,   $b483,   $8618,   $9791,   $e32e,   $f2a7,   $c03c,   $d1b5,   
          $2942,   $38cb,   $0a50,   $1bd9,   $6f66,   $7eef,   $4c74,   $5dfd,   
          $b58b,   $a402,   $9699,   $8710,   $f3af,   $e226,   $d0bd,   $c134,   
          $39c3,   $284a,   $1ad1,   $0b58,   $7fe7,   $6e6e,   $5cf5,   $4d7c,   
          $c60c,   $d785,   $e51e,   $f497,   $8028,   $91a1,   $a33a,   $b2b3,   
          $4a44,   $5bcd,   $6956,   $78df,   $0c60,   $1de9,   $2f72,   $3efb,   
          $d68d,   $c704,   $f59f,   $e416,   $90a9,   $8120,   $b3bb,   $a232,   
          $5ac5,   $4b4c,   $79d7,   $685e,   $1ce1,   $0d68,   $3ff3,   $2e7a,   
          $e70e,   $f687,   $c41c,   $d595,   $a12a,   $b0a3,   $8238,   $93b1,   
          $6b46,   $7acf,   $4854,   $59dd,   $2d62,   $3ceb,   $0e70,   $1ff9,   
          $f78f,   $e606,   $d49d,   $c514,   $b1ab,   $a022,   $92b9,   $8330,   
          $7bc7,   $6a4e,   $58d5,   $495c,   $3de3,   $2c6a,   $1ef1,   $0f78);   
    
  implementation   
    
  function   Get_CRC16(const   pData:pointer;nLength:Integer):string;   
  var   
      fcs   :   Word;   
      p   :   PBYTE;   
  begin   
      p   :=   PBYTE(pData);   
      fcs   :=   $ffff;   
      while(nLength>0)do   
      begin   
          fcs   :=   (fcs   shr   8)   xor   CRCTable16[(fcs   xor   p^)   and   $ff];   
          Dec(nLength);   
          Inc(p);   
      end;   
      Result   :=   IntToStr(not   fcs);   
  end;   
    
  function   Check_CRC16(const   pData:Pointer;nLength:   Integer):Boolean;   
  var   
      fcs:Word;   
      p:PBYTE;   
  begin   
      p   :=   PBYTE(pData);   
      fcs   :=   $ffff;   
      while(nLength>0)   do   
      begin   
          fcs   :=   (fcs   shr   8)   xor   CRCTable16[(fcs   xor   p^)   and   $ff];   
          Dec(nLength);   
          Inc(p);   
      end;   
  end;   
    
  function   Get_CRC16Code(strValue   :   string)   :   string;   
  var   
      crc   ,   i:Word;   
  begin   
      crc   :=   0;   
      for   i:=   1   to   length(strValue)   do   
      begin   
          crc   :=   CRCTable16[(Byte(crc   shr   8)   and   $ff)   xor   (ord(strValue[i])   and   $ff)]   xor   (crc   shr   8);   
      end;   
      Result   :=   IntTohex(crc,2);   
  end;   

end.