lire gros fichier En C + CRC32

/* Table of CRCs of all 8-bit messages. */
unsigned long crc32_table[256];

/* Flag: has the table been computed? Initially false. */
int crc32_table_computed = 0;

/* Make the table for a fast CRC. */
void make_crc32_table(void)
{
  unsigned long c;
  int n, k;
  for (n = 0; n < 256; n++) {
    c = (unsigned long) n;
    for (k = 0; k < 8; k++) {
      if (c & 1) {
        c = 0xedb88320L ^ (c >> 1);
      } else {
        c = c >> 1;
      }
    }
    crc32_table[n] = c;
  }
  crc32_table_computed = 1;
}

unsigned long Update_CRC32(unsigned long crc, unsigned char *buf, int len)
{
  unsigned long c = crc ^ 0xffffffffL;
  int n;

  if (!crc32_table_computed)
    make_crc32_table();
  for (n = 0; n < len; n++) {
    c = crc32_table[(c ^ buf[n]) & 0xff] ^ (c >> 8);
  }
  return c ^ 0xffffffffL;
}

FILE *INFILE; 
unsigned long Calcul32;
Calcul32 = 0L; 
unsigned char Checksum[1024] = "";


INFILE = fopen("./cat/1.avi", "rb"); 
                         
                      
  // deplace le curseur a la fin
  fseek(INFILE,0,SEEK_END);
  // taille du fichier
  long sizeFile=ftell(INFILE);
  sizeFile = sizeFile + 1;
  // on se repositionne au debut
  fseek(INFILE,0,SEEK_SET);
  // allocation
  char * chaine =NULL;
  chaine =(char*)malloc(sizeFile);
                      
                
 if (INFILE != NULL){
  fgets(chaine, sizeFile, INFILE); // On lit maximum TAILLE_MAX caractères du fichier, on stocke le tout dans "chaine"
  printf("%s\n", chaine); // On affiche la chaîne
  Calcul32 = Update_CRC32(Calcul32, chaine, strlen(chaine));
  fclose(INFILE);
  free(chaine);
  sprintf(Checksum, "%08x", Calcul32);
                        
  printf("%s",Checksum);
}
free(chaine);
fclose(INFILE);

FILE *INFILE; 
unsigned long Calcul32;

unsigned char Checksum[10] = "";

const int Taille_Tampon = 64 * 1024;
unsigned long long int len;
unsigned char buffer[Taille_Tampon];

// Initialisation
Calcul32 = 0L;

INFILE = fopen("./cat/1.avi", "rb");
if (INFILE != NULL){

  // Ici se passe le calcul par blocs
  while (len = fread(buffer, 1, Taille_Tampon, INFILE)) {
    Calcul32 = Update_CRC32(Calcul32, buffer, strlen(chaine));
  }

}
fclose(INFILE);

sprintf(Checksum, "%08x", Calcul32);
printf("%s",Checksum);