X-Git-Url: http://cloudbase.mooo.com/gitweb/z180-stamp.git/blobdiff_plain/4bc81323e51ac138e733c14eeb6f283ae706e904..b30c4e8f1aef96f6fdc93da9f125545f5f74d06e:/fatfs/doc/res/app3.c

diff --git a/fatfs/doc/res/app3.c b/fatfs/doc/res/app3.c
new file mode 100644
index 0000000..c4cfcf5
--- /dev/null
+++ b/fatfs/doc/res/app3.c
@@ -0,0 +1,109 @@
+/*----------------------------------------------------------------------/
+/ 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.
+/-----------------------------------------------------------------------/
+/ This function can work with FatFs R0.09 - R0.11a.
+/ It is incompatible with R0.12+. Use f_expand function instead.
+/----------------------------------------------------------------------*/
+
+/* 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);  /* File is contiguous. Return the start sector */
+    }
+
+    /* File is not contiguous */
+#if _FS_READONLY
+    return 0;								/* Exit if in read-only cfg. */
+#else
+    if (!(fp->flag & FA_WRITE)) return 0;   /* Exit if the file object is for read-only */
+
+    if (f_truncate(fp)) return 0;           /* Remove the non-contiguous 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 to write */
+    f_mount(&fs, "", 0);
+    fr = f_open(&fil, "fastrec.log", FA_READ | FA_WRITE | FA_OPEN_ALWAYS);
+    if (fr) return 1;
+
+    /* Check if the file is 256MB in size and occupies a contiguous area.
+    /  If not, a contiguous area will be re-allocated to the file. */
+    org = allocate_contiguous_clusters(&fil, 0x10000000);
+    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 without file system layer. */
+    ...
+    dr = disk_write(fil.fs->drv, Buff, org, 1024);   /* Write 512KiB from top of the file */
+    ...
+
+    f_close(&fil);
+    return 0;
+}
+