Import fatfs R0.10c

[z180-stamp.git] / fatfs / doc / img / app3.c

/*----------------------------------------------------------------------/\r
/ Allocate a contiguous area to the file\r
/-----------------------------------------------------------------------/\r
/ This function checks if the file is contiguous with desired size.\r
/ If not, a block of contiguous sectors is allocated to the file.\r
/ If the file has been opened without FA_WRITE flag, it only checks if\r
/ the file is contiguous and returns the resulut. */\r
\r
#if _FATFS != 80367 /* Check if R0.10c */\r
#error This function may not be compatible with this revision of FatFs module.\r
#endif\r
\r
/* Declarations of FatFs internal functions accessible from applications.\r
/  This is intended to be used for disk checking/fixing or dirty hacks :-) */\r
DWORD clust2sect (FATFS* fs, DWORD clst);\r
DWORD get_fat (FATFS* fs, DWORD clst);\r
FRESULT put_fat (FATFS* fs, DWORD clst, DWORD val);\r
\r
\r
DWORD allocate_contiguous_clusters (    /* Returns the first sector in LBA (0:error or not contiguous) */\r
    FIL* fp,    /* Pointer to the open file object */\r
    DWORD len   /* Number of bytes to allocate */\r
)\r
{\r
    DWORD csz, tcl, ncl, ccl, cl;\r
\r
\r
    if (f_lseek(fp, 0) || !len)     /* Check if the given parameters are valid */\r
        return 0;\r
    csz = 512UL * fp->fs->csize;    /* Cluster size in unit of byte (assuming 512 bytes/sector) */\r
    tcl = (len + csz - 1) / csz;    /* Total number of clusters required */\r
    len = tcl * csz;                /* Round-up file size to the cluster boundary */\r
\r
    /* Check if the existing cluster chain is contiguous */\r
    if (len == fp->fsize) {\r
        ncl = 0; ccl = fp->sclust;\r
        do {\r
            cl = get_fat(fp->fs, ccl);  /* Get the cluster status */\r
            if (cl + 1 < 3) return 0;   /* Hard error? */\r
            if (cl != ccl + 1 &&; cl < fp->fs->n_fatent) break;  /* Not contiguous? */\r
            ccl = cl;\r
        } while (++ncl < tcl);\r
        if (ncl == tcl)             /* Is the file contiguous? */\r
            return clust2sect(fp->fs, fp->sclust);  /* Return file start sector */\r
    }\r
#if _FS_READONLY\r
    return 0;\r
#else\r
    if (f_truncate(fp)) return 0;   /* Remove the existing chain */\r
\r
    /* Find a free contiguous area */\r
    ccl = cl = 2; ncl = 0;\r
    do {\r
        if (cl >= fp->fs->n_fatent) return 0;   /* No contiguous area is found. */\r
        if (get_fat(fp->fs, cl)) {  /* Encounterd a cluster in use */\r
            do {    /* Skip the block of used clusters */\r
                cl++;\r
                if (cl >= fp->fs->n_fatent) return 0;   /* No contiguous area is found. */\r
            } while (get_fat(fp->fs, cl));\r
            ccl = cl; ncl = 0;\r
        }\r
        cl++; ncl++;\r
    } while (ncl < tcl);\r
\r
    /* Create a contiguous cluster chain */\r
    fp->fs->last_clust = ccl - 1;\r
    if (f_lseek(fp, len)) return 0;\r
\r
    return clust2sect(fp->fs, fp->sclust);  /* Return file start sector */\r
#endif\r
}\r
\r
\r
int main (void)\r
{\r
    FRESULT fr;\r
    DRESULT dr;\r
    FATFS fs;\r
    FIL fil;\r
    DWORD org;\r
\r
\r
    /* Open or create a file */\r
    f_mount(&fs, "", 0);\r
    fr = f_open(&fil, "swapfile.sys", FA_READ | FA_WRITE | FA_OPEN_ALWAYS);\r
    if (fr) return 1;\r
\r
    /* Check if the file is 64MB in size and occupies a contiguous area.\r
    /  If not, a contiguous area will be re-allocated to the file. */\r
    org = allocate_contiguous_clusters(&fil, 0x4000000);\r
    if (!org) {\r
        printf("Function failed due to any error or insufficient contiguous area.\n");\r
        f_close(&fil);\r
        return 1;\r
    }\r
\r
    /* Now you can read/write the file with disk functions bypassing the file system layer. */\r
\r
    dr = disk_write(fil.fs->drv, Buff, org, 1024);   /* Write 512KiB from top of the file */\r
\r
    ...\r
\r
    f_close(&fil);\r
    return 0;\r
}\r
\r