unit Crc8Unt;

interface

type
  PBYTE = ^Byte;

  //计算CRC校验码
function GetCrc8(const pData: Pointer; nLength: Integer): byte;

//校验函数
function CheckCRC8(const pData: Pointer; nLength: Integer; CrcValue: byte):
  Boolean;

implementation

uses SysUtils,yifanUnt;

const
  CRCTable8: array[0..255] of byte = (
   $00, $31, $62, $53, $C4, $F5, $A6, $97,
   $B9, $88, $DB, $EA, $7D, $4C, $1F, $2E,
   $43, $72, $21, $10, $87, $B6, $E5, $D4,
   $FA, $CB, $98, $A9, $3E, $0F, $5C, $6D,
   $86, $B7, $E4, $D5, $42, $73, $20, $11,
   $3F, $0E, $5D, $6C, $FB, $CA, $99, $A8,
   $C5, $F4, $A7, $96, $01, $30, $63, $52,
   $7C, $4D, $1E, $2F, $B8, $89, $DA, $EB,
   $3D, $0C, $5F, $6E, $F9, $C8, $9B, $AA,
   $84, $B5, $E6, $D7, $40, $71, $22, $13,
   $7E, $4F, $1C, $2D, $BA, $8B, $D8, $E9,
   $C7, $F6, $A5, $94, $03, $32, $61, $50,
   $BB, $8A, $D9, $E8, $7F, $4E, $1D, $2C,
   $02, $33, $60, $51, $C6, $F7, $A4, $95,
   $F8, $C9, $9A, $AB, $3C, $0D, $5E, $6F,
   $41, $70, $23, $12, $85, $B4, $E7, $D6,
   $7A, $4B, $18, $29, $BE, $8F, $DC, $ED,
   $C3, $F2, $A1, $90, $07, $36, $65, $54,
   $39, $08, $5B, $6A, $FD, $CC, $9F, $AE,
   $80, $B1, $E2, $D3, $44, $75, $26, $17,
   $FC, $CD, $9E, $AF, $38, $09, $5A, $6B,
   $45, $74, $27, $16, $81, $B0, $E3, $D2,
   $BF, $8E, $DD, $EC, $7B, $4A, $19, $28,
   $06, $37, $64, $55, $C2, $F3, $A0, $91,
   $47, $76, $25, $14, $83, $B2, $E1, $D0,
   $FE, $CF, $9C, $AD, $3A, $0B, $58, $69,
   $04, $35, $66, $57, $C0, $F1, $A2, $93,
   $BD, $8C, $DF, $EE, $79, $48, $1B, $2A,
   $C1, $F0, $A3, $92, $05, $34, $67, $56,
   $78, $49, $1A, $2B, $BC, $8D, $DE, $EF,
   $82, $B3, $E0, $D1, $46, $77, $24, $15,
   $3B, $0A, $59, $68, $FF, $CE, $9D, $AC);

function GetCrc8(const pData: Pointer; nLength: Integer): byte;
var
  fcs: byte;
  p: PBYTE;
begin
  p := PBYTE(PData);
  fcs := 0; //   初始化
  while (nLength > 0) do
  begin
   fcs := CRCTable8[fcs xor p^];
   Dec(nLength);
   Inc(p);
  end;
  result := fcs;
end;

function CheckCRC8(const pData: Pointer; nLength: Integer; CrcValue: byte):
  Boolean;
var
  fcs: byte;
  p: PBYTE;
begin
  p := PBYTE(PData);
  fcs := 0; //   初始化
  while (nLength > 0) do
  begin
   fcs := CRCTable8[fcs xor p^];
   Dec(nLength);
   Inc(p);
  end;
  Result := (fcs = CrcValue);
end;

end.