107 lines
3.7 KiB
C
107 lines
3.7 KiB
C
|
/*----------------------------------------------------------------------/
|
||
|
|
/ Allocate a contiguous area to the file
|
||
|
|
/-----------------------------------------------------------------------/
|
||
|
|
/ This function checks if the file is contiguous with desired size.
|
||
|
|
/ If not, a block of contiguous sectors is allocated to the file.
|
||
|
|
/ If the file has been opened without FA_WRITE flag, it only checks if
|
||
|
|
/ the file is contiguous and returns the resulut. */
|
||
|
|
|
||
|
|
#if _FATFS != 80960 /* Check if R0.10 */
|
||
|
|
#error This function may not be compatible with this revision of FatFs module.
|
||
|
|
#endif
|
||
|
|
|
||
|
|
/* Declarations of FatFs internal functions accessible from applications.
|
||
|
|
/ This is intended to be used for disk checking/fixing or dirty hacks :-) */
|
||
|
|
DWORD clust2sect (FATFS* fs, DWORD clst);
|
||
|
|
DWORD get_fat (FATFS* fs, DWORD clst);
|
||
|
|
FRESULT put_fat (FATFS* fs, DWORD clst, DWORD val);
|
||
|
|
|
||
|
|
|
||
|
|
DWORD allocate_contiguous_clusters ( /* Returns the first sector in LBA (0:error or not contiguous) */
|
||
|
|
FIL* fp, /* Pointer to the open file object */
|
||
|
|
DWORD len /* Number of bytes to allocate */
|
||
|
|
)
|
||
|
|
{
|
||
|
|
DWORD csz, tcl, ncl, ccl, cl;
|
||
|
|
|
||
|
|
|
||
|
|
if (f_lseek(fp, 0) || !len) /* Check if the given parameters are valid */
|
||
|
|
return 0;
|
||
|
|
csz = 512UL * fp->fs->csize; /* Cluster size in unit of byte (assuming 512 bytes/sector) */
|
||
|
|
tcl = (len + csz - 1) / csz; /* Total number of clusters required */
|
||
|
|
len = tcl * csz; /* Round-up file size to the cluster boundary */
|
||
|
|
|
||
|
|
/* Check if the existing cluster chain is contiguous */
|
||
|
|
if (len == fp->fsize) {
|
||
|
|
ncl = 0; ccl = fp->sclust;
|
||
|
|
do {
|
||
|
|
cl = get_fat(fp->fs, ccl); /* Get the cluster status */
|
||
|
|
if (cl + 1 < 3) return 0; /* Hard error? */
|
||
|
|
if (cl != ccl + 1 &&; cl < fp->fs->n_fatent) break; /* Not contiguous? */
|
||
|
|
ccl = cl;
|
||
|
|
} while (++ncl < tcl);
|
||
|
|
if (ncl == tcl) /* Is the file contiguous? */
|
||
|
|
return clust2sect(fp->fs, fp->sclust); /* Return file start sector */
|
||
|
|
}
|
||
|
|
#if _FS_READONLY
|
||
|
|
return 0;
|
||
|
|
#else
|
||
|
|
if (f_truncate(fp)) return 0; /* Remove the existing chain */
|
||
|
|
|
||
|
|
/* Find a free contiguous area */
|
||
|
|
ccl = cl = 2; ncl = 0;
|
||
|
|
do {
|
||
|
|
if (cl >= fp->fs->n_fatent) return 0; /* No contiguous area is found. */
|
||
|
|
if (get_fat(fp->fs, cl)) { /* Encounterd a cluster in use */
|
||
|
|
do { /* Skip the block of used clusters */
|
||
|
|
cl++;
|
||
|
|
if (cl >= fp->fs->n_fatent) return 0; /* No contiguous area is found. */
|
||
|
|
} while (get_fat(fp->fs, cl));
|
||
|
|
ccl = cl; ncl = 0;
|
||
|
|
}
|
||
|
|
cl++; ncl++;
|
||
|
|
} while (ncl < tcl);
|
||
|
|
|
||
|
|
/* Create a contiguous cluster chain */
|
||
|
|
fp->fs->last_clust = ccl - 1;
|
||
|
|
if (f_lseek(fp, len)) return 0;
|
||
|
|
|
||
|
|
return clust2sect(fp->fs, fp->sclust); /* Return file start sector */
|
||
|
|
#endif
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
int main (void)
|
||
|
|
{
|
||
|
|
FRESULT fr;
|
||
|
|
DRESULT dr;
|
||
|
|
FATFS fs;
|
||
|
|
FIL fil;
|
||
|
|
DWORD org;
|
||
|
|
|
||
|
|
|
||
|
|
/* Open or create a file */
|
||
|
|
f_mount(&fs, "", 0);
|
||
|
|
fr = f_open(&fil, "swapfile.sys", FA_READ | FA_WRITE | FA_OPEN_ALWAYS);
|
||
|
|
if (fr) return 1;
|
||
|
|
|
||
|
|
/* Check if the file is 64MB in size and occupies a contiguous area.
|
||
|
|
/ If not, a contiguous area will be re-allocated to the file. */
|
||
|
|
org = allocate_contiguous_clusters(&fil, 0x4000000);
|
||
|
|
if (!org) {
|
||
|
|
printf("Function failed due to any error or insufficient contiguous area.\n");
|
||
|
|
f_close(&fil);
|
||
|
|
return 1;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Now you can read/write the file with disk functions bypassing the file system layer. */
|
||
|
|
|
||
|
|
dr = disk_write(fil.fs->drv, Buff, org, 1024); /* Write 512Ki bytes from top of the file */
|
||
|
|
|
||
|
|
...
|
||
|
|
|
||
|
|
f_close(&fil);
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|