1 /*----------------------------------------------------------------------/
2 / Allocate a contiguous area to the file
3 /-----------------------------------------------------------------------/
4 / This function checks if the file is contiguous with desired size.
5 / If not, a block of contiguous sectors is allocated to the file.
6 / If the file has been opened without FA_WRITE flag, it only checks if
7 / the file is contiguous and returns the resulut.
8 /-----------------------------------------------------------------------/
9 / This function can work with FatFs R0.09 - R0.11a.
10 / It is incompatible with R0.12+. Use f_expand function instead.
11 /----------------------------------------------------------------------*/
12
13 /* Declarations of FatFs internal functions accessible from applications.
14 / This is intended to be used for disk checking/fixing or dirty hacks :-) */
15 DWORD clust2sect (FATFS* fs, DWORD clst);
16 DWORD get_fat (FATFS* fs, DWORD clst);
17 FRESULT put_fat (FATFS* fs, DWORD clst, DWORD val);
18
19
allocate_contiguous_clusters(FIL * fp,DWORD len)20 DWORD allocate_contiguous_clusters ( /* Returns the first sector in LBA (0:error or not contiguous) */
21 FIL* fp, /* Pointer to the open file object */
22 DWORD len /* Number of bytes to allocate */
23 )
24 {
25 DWORD csz, tcl, ncl, ccl, cl;
26
27
28 if (f_lseek(fp, 0) || !len) /* Check if the given parameters are valid */
29 return 0;
30 csz = 512UL * fp->fs->csize; /* Cluster size in unit of byte (assuming 512 bytes/sector) */
31 tcl = (len + csz - 1) / csz; /* Total number of clusters required */
32 len = tcl * csz; /* Round-up file size to the cluster boundary */
33
34 /* Check if the existing cluster chain is contiguous */
35 if (len == fp->fsize) {
36 ncl = 0; ccl = fp->sclust;
37 do {
38 cl = get_fat(fp->fs, ccl); /* Get the cluster status */
39 if (cl + 1 < 3) return 0; /* Hard error? */
40 if (cl != ccl + 1 && cl < fp->fs->n_fatent) break; /* Not contiguous? */
41 ccl = cl;
42 } while (++ncl < tcl);
43 if (ncl == tcl) /* Is the file contiguous? */
44 return clust2sect(fp->fs, fp->sclust); /* File is contiguous. Return the start sector */
45 }
46
47 /* File is not contiguous */
48 #if _FS_READONLY
49 return 0; /* Exit if in read-only cfg. */
50 #else
51 if (!(fp->flag & FA_WRITE)) return 0; /* Exit if the file object is for read-only */
52
53 if (f_truncate(fp)) return 0; /* Remove the non-contiguous chain */
54
55 /* Find a free contiguous area */
56 ccl = cl = 2; ncl = 0;
57 do {
58 if (cl >= fp->fs->n_fatent) return 0; /* No contiguous area is found. */
59 if (get_fat(fp->fs, cl)) { /* Encounterd a cluster in use */
60 do { /* Skip the block of used clusters */
61 cl++;
62 if (cl >= fp->fs->n_fatent) return 0; /* No contiguous area is found. */
63 } while (get_fat(fp->fs, cl));
64 ccl = cl; ncl = 0;
65 }
66 cl++; ncl++;
67 } while (ncl < tcl);
68
69 /* Create a contiguous cluster chain */
70 fp->fs->last_clust = ccl - 1;
71 if (f_lseek(fp, len)) return 0;
72
73 return clust2sect(fp->fs, fp->sclust); /* Return file start sector */
74 #endif
75 }
76
77
main(void)78 int main (void)
79 {
80 FRESULT fr;
81 DRESULT dr;
82 FATFS fs;
83 FIL fil;
84 DWORD org;
85
86
87 /* Open or create a file to write */
88 f_mount(&fs, "", 0);
89 fr = f_open(&fil, "fastrec.log", FA_READ | FA_WRITE | FA_OPEN_ALWAYS);
90 if (fr) return 1;
91
92 /* Check if the file is 256MB in size and occupies a contiguous area.
93 / If not, a contiguous area will be re-allocated to the file. */
94 org = allocate_contiguous_clusters(&fil, 0x10000000);
95 if (!org) {
96 printf("Function failed due to any error or insufficient contiguous area.\n");
97 f_close(&fil);
98 return 1;
99 }
100
101 /* Now you can read/write the file without filesystem layer. */
102 ...
103 dr = disk_write(fil.fs->drv, Buff, org, 1024); /* Write 512KiB from top of the file */
104 ...
105
106 f_close(&fil);
107 return 0;
108 }
109
110