diff options
Diffstat (limited to '3rdparty/fatfs-0.10b/doc/img/app3.c')
| -rw-r--r-- | 3rdparty/fatfs-0.10b/doc/img/app3.c | 106 |
1 files changed, 106 insertions, 0 deletions
diff --git a/3rdparty/fatfs-0.10b/doc/img/app3.c b/3rdparty/fatfs-0.10b/doc/img/app3.c new file mode 100644 index 00000000..32b14237 --- /dev/null +++ b/3rdparty/fatfs-0.10b/doc/img/app3.c @@ -0,0 +1,106 @@ +/*----------------------------------------------------------------------/ +/ 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 != 8051 /* Check if R0.10b */ +#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 512KiB from top of the file */ + + ... + + f_close(&fil); + return 0; +} + |