fatfs/documents/res/app5.c

   1 /*----------------------------------------------------------------------/
   2 / Test if the file is contiguous                                        /
   3 /----------------------------------------------------------------------*/
   4
   5 FRESULT test_contiguous_file (
   6     FIL* fp,    /* [IN]  Open file object to be checked */
   7     int* cont   /* [OUT] 1:Contiguous, 0:Fragmented or zero-length */
   8 )
   9 {
  10     DWORD clst, clsz, step;
  11     FSIZE_t fsz;
  12     FRESULT fr;
  13
  14
  15     *cont = 0;
  16     fr = f_rewind(fp);              /* Validates and prepares the file */
  17     if (fr != FR_OK) return fr;
  18
  19 #if FF_MAX_SS == FF_MIN_SS
  20     clsz = (DWORD)fp->obj.fs->csize * FF_MAX_SS;    /* Cluster size */
  21 #else
  22     clsz = (DWORD)fp->obj.fs->csize * fp->obj.fs->ssize;
  23 #endif
  24     fsz = f_size(fp);
  25     if (fsz > 0) {
  26         clst = fp->obj.sclust - 1;  /* A cluster leading the first cluster for first test */
  27         while (fsz) {
  28             step = (fsz >= clsz) ? clsz : (DWORD)fsz;
  29             fr = f_lseek(fp, f_tell(fp) + step);    /* Advances file pointer a cluster */
  30             if (fr != FR_OK) return fr;
  31             if (clst + 1 != fp->clust) break;       /* Is not the cluster next to previous one? */
  32             clst = fp->clust; fsz -= step;          /* Get current cluster for next test */
  33         }
  34         if (fsz == 0) *cont = 1;    /* All done without fail? */
  35     }
  36
  37     return FR_OK;
  38 }