crcmac_unit.pas

这是一个非常实用的实时串口通讯程序

unit CRCMAC_Unit;

interface

  function chkcrc16(usDataLen : integer;puchMsg : PChar) : Word;

implementation

const
  auchCRCHi : array[0..255] of byte = (
    $00,$C1,$81,$40,$01,$C0,$80,$41,$01,$C0,$80,$41,$00,$C1,$81,$40,
    $01,$C0,$80,$41,$00,$C1,$81,$40,$00,$C1,$81,$40,$01,$C0,$80,$41,
    $01,$C0,$80,$41,$00,$C1,$81,$40,$00,$C1,$81,$40,$01,$C0,$80,$41,
    $00,$C1,$81,$40,$01,$C0,$80,$41,$01,$C0,$80,$41,$00,$C1,$81,$40,
    $01,$C0,$80,$41,$00,$C1,$81,$40,$00,$C1,$81,$40,$01,$C0,$80,$41,
    $00,$C1,$81,$40,$01,$C0,$80,$41,$01,$C0,$80,$41,$00,$C1,$81,$40,
    $00,$C1,$81,$40,$01,$C0,$80,$41,$01,$C0,$80,$41,$00,$C1,$81,$40,
    $01,$C0,$80,$41,$00,$C1,$81,$40,$00,$C1,$81,$40,$01,$C0,$80,$41,
    $01,$C0,$80,$41,$00,$C1,$81,$40,$00,$C1,$81,$40,$01,$C0,$80,$41,
    $00,$C1,$81,$40,$01,$C0,$80,$41,$01,$C0,$80,$41,$00,$C1,$81,$40,
    $00,$C1,$81,$40,$01,$C0,$80,$41,$01,$C0,$80,$41,$00,$C1,$81,$40,
    $01,$C0,$80,$41,$00,$C1,$81,$40,$00,$C1,$81,$40,$01,$C0,$80,$41,
    $00,$C1,$81,$40,$01,$C0,$80,$41,$01,$C0,$80,$41,$00,$C1,$81,$40,
    $01,$C0,$80,$41,$00,$C1,$81,$40,$00,$C1,$81,$40,$01,$C0,$80,$41,
    $01,$C0,$80,$41,$00,$C1,$81,$40,$00,$C1,$81,$40,$01,$C0,$80,$41,
    $00,$C1,$81,$40,$01,$C0,$80,$41,$01,$C0,$80,$41,$00,$C1,$81,$40
    );

// table of CRC values for low-order byte
  auchCRCLo : array[0..255] of byte = (
    $00,$C0,$C1,$01,$C3,$03,$02,$C2,$C6,$06,$07,$C7,$05,$C5,$C4,$04,
    $CC,$0C,$0D,$CD,$0F,$CF,$CE,$0E,$0A,$CA,$CB,$0B,$C9,$09,$08,$C8,
    $D8,$18,$19,$D9,$1B,$DB,$DA,$1A,$1E,$DE,$DF,$1F,$DD,$1D,$1C,$DC,
    $14,$D4,$D5,$15,$D7,$17,$16,$D6,$D2,$12,$13,$D3,$11,$D1,$D0,$10,
    $F0,$30,$31,$F1,$33,$F3,$F2,$32,$36,$F6,$F7,$37,$F5,$35,$34,$F4,
    $3C,$FC,$FD,$3D,$FF,$3F,$3E,$FE,$FA,$3A,$3B,$FB,$39,$F9,$F8,$38,
    $28,$E8,$E9,$29,$EB,$2B,$2A,$EA,$EE,$2E,$2F,$EF,$2D,$ED,$EC,$2C,
    $E4,$24,$25,$E5,$27,$E7,$E6,$26,$22,$E2,$E3,$23,$E1,$21,$20,$E0,
    $A0,$60,$61,$A1,$63,$A3,$A2,$62,$66,$A6,$A7,$67,$A5,$65,$64,$A4,
    $6C,$AC,$AD,$6D,$AF,$6F,$6E,$AE,$AA,$6A,$6B,$AB,$69,$A9,$A8,$68,
    $78,$B8,$B9,$79,$BB,$7B,$7A,$BA,$BE,$7E,$7F,$BF,$7D,$BD,$BC,$7C,
    $B4,$74,$75,$B5,$77,$B7,$B6,$76,$72,$B2,$B3,$73,$B1,$71,$70,$B0,
    $50,$90,$91,$51,$93,$53,$52,$92,$96,$56,$57,$97,$55,$95,$94,$54,
    $9C,$5C,$5D,$9D,$5F,$9F,$9E,$5E,$5A,$9A,$9B,$5B,$99,$59,$58,$98,
    $88,$48,$49,$89,$4B,$8B,$8A,$4A,$4E,$8E,$8F,$4F,$8D,$4D,$4C,$8C,
    $44,$84,$85,$45,$87,$47,$46,$86,$82,$42,$43,$83,$41,$81,$80,$40
    );

function chkcrc16(usDataLen : integer;puchMsg : PChar) : Word;
var
  uchCRCHi,uchCRCLo : byte;
  uIndex : word;
begin
    uchCRCHi:=$00;
    uchCRCLo:=$00;
    while(usDataLen > 0) do
    begin
        uIndex := word(uchCRCHi) xor word(puchMsg^);
        inc(puchMsg);
        uchCRCHi := uchCRCLo xor auchCRCHi[uIndex];
        uchCRCLo := auchCRCLo[uIndex];
        dec(usDataLen);
    end;
    Result := ((uchCRCHi shl 8) or uchCRCLo);
end;

end.