idhashcrc.pas

Indy控件的使用源代码

{ $HDR$}
{**********************************************************************}
{ Unit archived using Team Coherence                                   }
{ Team Coherence is Copyright 2002 by Quality Software Components      }
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{}
{ $Log:  10179: IdHashCRC.pas 
{
{   Rev 1.0    2002.11.12 10:40:08 PM  czhower
}
unit IdHashCRC;

{
2001-Oct-23 Pete Mee
 - Fixed CRC-32.
}

interface

uses
  Classes,
  IdHash;


type
  TIdHashCRC16 = class(TIdHash16)
  public
    function HashValue(AStream: TStream): Word; override;
  end;

  TIdHashCRC32 = class(TIdHash32)
  public
    function HashValue(AStream: TStream): LongWord; override;
  end;

implementation

uses
  SysUtils;

const

  CRC16Table:  array[0..255] OF WORD =
     ($0000,$C0C1,$C181,$0140,$C301,$03C0,$0280,$C241,$C601,$06C0,$0780,
      $C741,$0500,$C5C1,$C481,$0440,$CC01,$0CC0,$0D80,$CD41,$0F00,$CFC1,
      $CE81,$0E40,$0A00,$CAC1,$CB81,$0B40,$C901,$09C0,$0880,$C841,$D801,
      $18C0,$1980,$D941,$1B00,$DBC1,$DA81,$1A40,$1E00,$DEC1,$DF81,$1F40,
      $DD01,$1DC0,$1C80,$DC41,$1400,$D4C1,$D581,$1540,$D701,$17C0,$1680,
      $D641,$D201,$12C0,$1380,$D341,$1100,$D1C1,$D081,$1040,$F001,$30C0,
      $3180,$F141,$3300,$F3C1,$F281,$3240,$3600,$F6C1,$F781,$3740,$F501,
      $35C0,$3480,$F441,$3C00,$FCC1,$FD81,$3D40,$FF01,$3FC0,$3E80,$FE41,
      $FA01,$3AC0,$3B80,$FB41,$3900,$F9C1,$F881,$3840,$2800,$E8C1,$E981,
      $2940,$EB01,$2BC0,$2A80,$EA41,$EE01,$2EC0,$2F80,$EF41,$2D00,$EDC1,
      $EC81,$2C40,$E401,$24C0,$2580,$E541,$2700,$E7C1,$E681,$2640,$2200,
      $E2C1,$E381,$2340,$E101,$21C0,$2080,$E041,$A001,$60C0,$6180,$A141,
      $6300,$A3C1,$A281,$6240,$6600,$A6C1,$A781,$6740,$A501,$65C0,$6480,
      $A441,$6C00,$ACC1,$AD81,$6D40,$AF01,$6FC0,$6E80,$AE41,$AA01,$6AC0,
      $6B80,$AB41,$6900,$A9C1,$A881,$6840,$7800,$B8C1,$B981,$7940,$BB01,
      $7BC0,$7A80,$BA41,$BE01,$7EC0,$7F80,$BF41,$7D00,$BDC1,$BC81,$7C40,
      $B401,$74C0,$7580,$B541,$7700,$B7C1,$B681,$7640,$7200,$B2C1,$B381,
      $7340,$B101,$71C0,$7080,$B041,$5000,$90C1,$9181,$5140,$9301,$53C0,
      $5280,$9241,$9601,$56C0,$5780,$9741,$5500,$95C1,$9481,$5440,$9C01,
      $5CC0,$5D80,$9D41,$5F00,$9FC1,$9E81,$5E40,$5A00,$9AC1,$9B81,$5B40,
      $9901,$59C0,$5880,$9841,$8801,$48C0,$4980,$8941,$4B00,$8BC1,$8A81,
      $4A40,$4E00,$8EC1,$8F81,$4F40,$8D01,$4DC0,$4C80,$8C41,$4400,$84C1,
      $8581,$4540,$8701,$47C0,$4680,$8641,$8201,$42C0,$4380,$8341,$4100,
      $81C1,$8081,$4040);

  CRC32Table : array[0..255] of longword = (
      $00000000, $77073096, $ee0e612c, $990951ba, $076dc419,
      $706af48f, $e963a535, $9e6495a3, $0edb8832, $79dcb8a4,
      $e0d5e91e, $97d2d988, $09b64c2b, $7eb17cbd, $e7b82d07,
      $90bf1d91, $1db71064, $6ab020f2, $f3b97148, $84be41de,
      $1adad47d, $6ddde4eb, $f4d4b551, $83d385c7, $136c9856,
      $646ba8c0, $fd62f97a, $8a65c9ec, $14015c4f, $63066cd9,
      $fa0f3d63, $8d080df5, $3b6e20c8, $4c69105e, $d56041e4,
      $a2677172, $3c03e4d1, $4b04d447, $d20d85fd, $a50ab56b,
      $35b5a8fa, $42b2986c, $dbbbc9d6, $acbcf940, $32d86ce3,
      $45df5c75, $dcd60dcf, $abd13d59, $26d930ac, $51de003a,
      $c8d75180, $bfd06116, $21b4f4b5, $56b3c423, $cfba9599,
      $b8bda50f, $2802b89e, $5f058808, $c60cd9b2, $b10be924,
      $2f6f7c87, $58684c11, $c1611dab, $b6662d3d, $76dc4190,
      $01db7106, $98d220bc, $efd5102a, $71b18589, $06b6b51f,
      $9fbfe4a5, $e8b8d433, $7807c9a2, $0f00f934, $9609a88e,
      $e10e9818, $7f6a0dbb, $086d3d2d, $91646c97, $e6635c01,
      $6b6b51f4, $1c6c6162, $856530d8, $f262004e, $6c0695ed,
      $1b01a57b, $8208f4c1, $f50fc457, $65b0d9c6, $12b7e950,
      $8bbeb8ea, $fcb9887c, $62dd1ddf, $15da2d49, $8cd37cf3,
      $fbd44c65, $4db26158, $3ab551ce, $a3bc0074, $d4bb30e2,
      $4adfa541, $3dd895d7, $a4d1c46d, $d3d6f4fb, $4369e96a,
      $346ed9fc, $ad678846, $da60b8d0, $44042d73, $33031de5,
      $aa0a4c5f, $dd0d7cc9, $5005713c, $270241aa, $be0b1010,
      $c90c2086, $5768b525, $206f85b3, $b966d409, $ce61e49f,
      $5edef90e, $29d9c998, $b0d09822, $c7d7a8b4, $59b33d17,
      $2eb40d81, $b7bd5c3b, $c0ba6cad, $edb88320, $9abfb3b6,
      $03b6e20c, $74b1d29a, $ead54739, $9dd277af, $04db2615,
      $73dc1683, $e3630b12, $94643b84, $0d6d6a3e, $7a6a5aa8,
      $e40ecf0b, $9309ff9d, $0a00ae27, $7d079eb1, $f00f9344,
      $8708a3d2, $1e01f268, $6906c2fe, $f762575d, $806567cb,
      $196c3671, $6e6b06e7, $fed41b76, $89d32be0, $10da7a5a,
      $67dd4acc, $f9b9df6f, $8ebeeff9, $17b7be43, $60b08ed5,
      $d6d6a3e8, $a1d1937e, $38d8c2c4, $4fdff252, $d1bb67f1,
      $a6bc5767, $3fb506dd, $48b2364b, $d80d2bda, $af0a1b4c,
      $36034af6, $41047a60, $df60efc3, $a867df55, $316e8eef,
      $4669be79, $cb61b38c, $bc66831a, $256fd2a0, $5268e236,
      $cc0c7795, $bb0b4703, $220216b9, $5505262f, $c5ba3bbe,
      $b2bd0b28, $2bb45a92, $5cb36a04, $c2d7ffa7, $b5d0cf31,
      $2cd99e8b, $5bdeae1d, $9b64c2b0, $ec63f226, $756aa39c,
      $026d930a, $9c0906a9, $eb0e363f, $72076785, $05005713,
      $95bf4a82, $e2b87a14, $7bb12bae, $0cb61b38, $92d28e9b,
      $e5d5be0d, $7cdcefb7, $0bdbdf21, $86d3d2d4, $f1d4e242,
      $68ddb3f8, $1fda836e, $81be16cd, $f6b9265b, $6fb077e1,
      $18b74777, $88085ae6, $ff0f6a70, $66063bca, $11010b5c,
      $8f659eff, $f862ae69, $616bffd3, $166ccf45, $a00ae278,
      $d70dd2ee, $4e048354, $3903b3c2, $a7672661, $d06016f7,
      $4969474d, $3e6e77db, $aed16a4a, $d9d65adc, $40df0b66,
      $37d83bf0, $a9bcae53, $debb9ec5, $47b2cf7f, $30b5ffe9,
      $bdbdf21c, $cabac28a, $53b39330, $24b4a3a6, $bad03605,
      $cdd70693, $54de5729, $23d967bf, $b3667a2e, $c4614ab8,
      $5d681b02, $2a6f2b94, $b40bbe37, $c30c8ea1, $5a05df1b,
      $2d02ef8d);

{ TIdHashCRC16 }

function TIdHashCRC16.HashValue(AStream: TStream): Word;
var
  i: Integer;
  Buf: byte;
begin
  Result := 0;
  for i := 1 to AStream.Size do begin
    AStream.ReadBuffer(Buf, SizeOf(Buf));
    Result := Hi(Result) xor CRC16Table[ Buf xor Lo(Result)];
  end;
end;

{ TIdHashCRC32 }

function TIdHashCRC32.HashValue(AStream: TStream): LongWord;
var
  i: Integer;
  LByte: Byte;
begin
  Result := $FFFFFFFF;
  // Faster than a while - While would read .Size which is slow
  for i := 1 to AStream.Size do begin
    //TODO: See if this and Elf would be faster by reading into a larger buffer and scanning that
    //buffer.
    AStream.ReadBuffer(LByte, SizeOf(LByte));
    Result := ((Result shr 8) and $00FFFFFF) xor CRC32Table[(Result xor LByte) and $FF];
  end;
  Result := Result xor $FFFFFFFF;
end;

end.