Calculateur de Block dans une Chaine de caractere

salut ,
j'ai un petit souci a ce calculateur de CRC32
voila un extrait de ma source binaire :
55 AA 01 01 00 17 17 6C 01 73 29 34 21 15 5A 5A
00 00 7F E6 00 00 00 00 10 00 60 BB 76 21 22 2B
22 5E D7 76 D3 76 51 D4 40 73 E0 40 D2 45 D8 41
37 C9 B3 51 5A 5A .......................etc
voila ce que que presente mon fichier binaire
il a des separteurs 5A5A
de 55AA Jusqua 5A5A ce présente comme un block et apres
de 00 juqua 5A5A ces le 2eme block et ainsi de suite les séparateurs de blocks ces 5A5A .
ici on calcule le checksum .
comment calculer un checksum
on prend la 1er ligne ou le premier Block
on calcule le checksum de 55AA jusqua 0173 ce qui veu dire le checksum ces positionné 4byte avant 5A5A . voila procedure de ce calculateur et meme il calcule et s'il a trouve le checksum Faux il le remplace un le Bon et ainsi de suite avec tout le fichier qui contient 2MegaOctet .
le Code du Checksum :
unit CRC32;
 
interface
 
procedure CalcCRC32(p: pointer; n: integer; var crc32: longword);
 
implementation
 
procedure CalcCRC32(p: pointer; n: integer; var crc32: longword);
const crc32table: array[0..255]oflongword = (
    $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, $2d02ef8d
  );
type
  buffer = array[0..0]ofbyte;
var
  i: integer; q: ^buffer; begin
  crc32 := crc32 xor$ffffffff;
 
  q := p;
  for i := 0to n-1do
    crc32 := crc32table[(crc32 xor(q^[i]))and$ff]xor(crc32 shr8);
 
  crc32 := crc32 xor$ffffffff;
end;
 
end.est Merci D'avance .