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Дмитрий Д.   (2002-01-31 13:12) [1]

лови готовый юнит, а конкретно принцип поищи в инете

unit Crc32fast;

interface

uses
Windows, classes
,Sysutils, Dialogs;

function FileCRC32fast(const FileName : String) : DWORD;
function UpdateCRC32(InitCRC : DWORD; BufPtr : Pointer; Len : Word) : LongInt;

implementation

type
CRCTable = array [0..255] of DWORD;

const
BufLen = 32768;

CRC32Table : CRCTable =
($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, $04fdff252,
$d1bb67f1, $a6bc5767, $3fb506dd, $048b2364b,
$d80d2bda, $af0a1b4c, $36034af6, $041047a60,
$df60efc3, $a867df55, $316e8eef, $04669be79,

$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);

var
Buf : array [1..BufLen] of Byte;

function UpdateCRC32(InitCRC : DWORD; BufPtr : Pointer; Len : Word) : LongInt;
var
crc : DWORD;
index : Integer;
i : DWORD;
begin
crc := InitCRC;
for i:=0 to Len-1 do begin
index := (crc xor DWORD(Pointer(DWORD(BufPtr)+i)^)) and $000000FF;
crc := ((crc shr 8) and $00FFFFFF) xor CRC32Table[index];
end;
Result := crc;
end;

function FileCRC32fast(const FileName : String) : DWORD;
var
InFile : TFileStream;
crc32 : DWORD;
Res : Integer;
BufPtr : Pointer;
begin
BufPtr := @Buf;
InFile:=TFileStream.Create(FileName,fmShareDenyNone);
crc32 := $FFFFFFFF;
Res:=InFile.Read(Buf,BufLen);
While (Res <> 0) do
begin
crc32 := UpdateCrc32(crc32,BufPtr,Res);
Res:=InFile.Read(Buf,BufLen);
end;
InFile.Destroy;
Result := not crc32;
end;

end.

---

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