unit Crc16Unt;

interface

type
  PBYTE = ^Byte;

  //计算CRC校验码
function GetCrc16(const pData: Pointer; nLength: Integer): Word;

//校验函数
function CheckCRC16(const pData: Pointer; nLength: Integer;CrcValue:Word): Boolean;

implementation

const
  CRCTable16: array[0..255] of Word = (
  $0000, $1021, $2042, $3063, $4084, $50A5, $60C6, $70E7,
  $8108, $9129, $A14A, $B16B, $C18C, $D1AD, $E1CE, $F1EF,
  $1231, $0210, $3273, $2252, $52B5, $4294, $72F7, $62D6,
  $9339, $8318, $B37B, $A35A, $D3BD, $C39C, $F3FF, $E3DE,
  $2462, $3443, $0420, $1401, $64E6, $74C7, $44A4, $5485,
  $A56A, $B54B, $8528, $9509, $E5EE, $F5CF, $C5AC, $D58D,
  $3653, $2672, $1611, $0630, $76D7, $66F6, $5695, $46B4,
  $B75B, $A77A, $9719, $8738, $F7DF, $E7FE, $D79D, $C7BC,
  $48C4, $58E5, $6886, $78A7, $0840, $1861, $2802, $3823,
  $C9CC, $D9ED, $E98E, $F9AF, $8948, $9969, $A90A, $B92B,
  $5AF5, $4AD4, $7AB7, $6A96, $1A71, $0A50, $3A33, $2A12,
  $DBFD, $CBDC, $FBBF, $EB9E, $9B79, $8B58, $BB3B, $AB1A,
  $6CA6, $7C87, $4CE4, $5CC5, $2C22, $3C03, $0C60, $1C41,
  $EDAE, $FD8F, $CDEC, $DDCD, $AD2A, $BD0B, $8D68, $9D49,
  $7E97, $6EB6, $5ED5, $4EF4, $3E13, $2E32, $1E51, $0E70,
  $FF9F, $EFBE, $DFDD, $CFFC, $BF1B, $AF3A, $9F59, $8F78,
  $9188, $81A9, $B1CA, $A1EB, $D10C, $C12D, $F14E, $E16F,
  $1080, $00A1, $30C2, $20E3, $5004, $4025, $7046, $6067,
  $83B9, $9398, $A3FB, $B3DA, $C33D, $D31C, $E37F, $F35E,
  $02B1, $1290, $22F3, $32D2, $4235, $5214, $6277, $7256,
  $B5EA, $A5CB, $95A8, $8589, $F56E, $E54F, $D52C, $C50D,
  $34E2, $24C3, $14A0, $0481, $7466, $6447, $5424, $4405,
  $A7DB, $B7FA, $8799, $97B8, $E75F, $F77E, $C71D, $D73C,
  $26D3, $36F2, $0691, $16B0, $6657, $7676, $4615, $5634,
  $D94C, $C96D, $F90E, $E92F, $99C8, $89E9, $B98A, $A9AB,
  $5844, $4865, $7806, $6827, $18C0, $08E1, $3882, $28A3,
  $CB7D, $DB5C, $EB3F, $FB1E, $8BF9, $9BD8, $ABBB, $BB9A,
  $4A75, $5A54, $6A37, $7A16, $0AF1, $1AD0, $2AB3, $3A92,
  $FD2E, $ED0F, $DD6C, $CD4D, $BDAA, $AD8B, $9DE8, $8DC9,
  $7C26, $6C07, $5C64, $4C45, $3CA2, $2C83, $1CE0, $0CC1,
  $EF1F, $FF3E, $CF5D, $DF7C, $AF9B, $BFBA, $8FD9, $9FF8,
  $6E17, $7E36, $4E55, $5E74, $2E93, $3EB2, $0ED1, $1EF0
   );

function GetCrc16(const pData: Pointer; nLength: Integer): Word;
var
  fcs: Word;
  p: PBYTE;
begin
  p := PBYTE(PData);
  fcs := 0; //   初始化
  while (nLength > 0) do
  begin
   fcs := (fcs shl 8) xor CRCTable16[((fcs shr 8) xor p^) and $FF];
   Dec(nLength);
   Inc(p);
  end;
  result := fcs; //取反
end;

function CheckCRC16(const pData: Pointer; nLength: Integer;CrcValue:Word): Boolean;
var
  fcs: Word;
  p: PBYTE;
begin
  p := PBYTE(pData);
  fcs := 0; //初始化
  while (nLength > 0) do
  begin
   fcs := (fcs shl 8) xor CRCTable16[((fcs shr 8) xor p^) and $FF];
   Dec(nLength);
   Inc(p);
  end;
  Result := (fcs = CrcValue);
end;

end.