Github/fatfs
1
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

R0.15b

Browse Source
This commit is contained in:
Christopher Williams
2025-06-23 16:37:39 -07:00
parent ff60b17ea7
commit 79eff96e0b
18 changed files with 460 additions and 327 deletions
Download Patch File Download Diff File Expand all files Collapse all files
documents/doc/mkfs.html
+4 -4
View File
@@ -35,11 +35,11 @@ FRESULT f_mkfs (
<dt>BYTE n_fat</dt>
<dd>Specifies number of FAT copies on the FAT/FAT32 volume. Valid value for this member is 1 or 2. The default value (0) and any invaid value gives 1. If the FAT type is exFAT, this member has no effect.</dd>
<dt>UINT align</dt>
<dd>Specifies alignment of the volume data area (file allocation pool, usually erase block boundary of flash memory media) <em>in unit of sector</em>. The valid value for this member is between 1 and 32768 inclusive in power of 2. If a zero (the default value) or any invalid value is given, the function obtains the block size from lower layer with <tt>disk_ioctl</tt> function.</dd>
<dd>Specifies alignment of the volume data area (file allocation pool, usually erase block boundary of flash memory media) <em>in unit of sector</em>. The valid value for this member is between 1 and 32768 inclusive in power of 2. If a zero (the default value) or an invalid value is given, the function obtains the block size from lower layer with <tt>disk_ioctl</tt> function.</dd>
<dt>UINT n_root</dt>
<dd>Specifies number of root directory entries on the FAT volume. Valid value for this member is up to 32768 and aligned to sector size / 32. The default value (0) and any invaid value gives 512. If the FAT type is FAT32 or exFAT, this member has no effect.</dd>
<dt>DWORD au_size</dt>
<dd>Specifies size of the cluster (allocation unit) <em>in unit of byte</em>. The valid value for this member is between sector size and 128 * sector size inclusive in power of 2 for FAT/FAT32 volume and up to 16 MB in power of 2 for exFAT volume. If a zero (default value) or any invalid value is given, the function uses a default cluster size depends on the volume size.</dd>
<dd>Specifies size of the cluster (allocation unit) <em>in unit of byte</em>. The valid value for this member is between sector size and 128 * sector size inclusive in power of 2 for FAT/FAT32 volume and up to 16 MB in power of 2 for exFAT volume. If a zero (default value) or an invalid value is given, the function uses a default cluster size depends on the volume size.</dd>
</dl>
<dt>work</dt>
<dd>Pointer to the working buffer used for the format process. If a null pointer is given with <tt><a href="config.html#use_lfn">FF_USE_LFN</a> == 3</tt>, the function uses a <tt>len</tt> bytes of heap memory in this function.</dd>
@@ -68,8 +68,8 @@ FRESULT f_mkfs (
<p>The allocation unit, also known as <em>cluster</em>, is a unit of disk space allocation for files. When the size of allocation unit is 32768 bytes, a file with 100 bytes in size occupies 32768 bytes of disk space. The space efficiency of disk usage gets worse as increasing size of allocation unit, but, on the other hand, the read/write performance increases. Therefore the size of allocation unit is a trade-off between space efficiency and performance. For the large volumes in GB order, 32768 bytes or larger, automatically selected by default, is recommended for most case unless extremely many small files are created in the volume.</p>
<p>When the logical drive to be formatted is associated with a physical drive (<tt><a href="config.html#multi_partition">FF_MULTI_PARTITION</a> == 0</tt> or <tt>VolToPart[].pt == 0</tt>) and <tt>FM_SFD</tt> flag is not specified, a partition occupies entire drive space is created and then the FAT volume is created in the partition. When <tt>FM_SFD</tt> flag is specified, the FAT volume is created without any disk partitioning.</p>
<p>When the logical drive to be formatted is associated with a specific partition by multiple partition feature (<tt>FF_MULTI_PARTITION == 1</tt> and <tt>VolToPart[].pt &gt; 0</tt>), the FAT volume is created in the partition of the physical drive specified by <a href="filename.html#vol">volume mapping table</a> and <tt>FM_SFD</tt> flag is ignored. The hosting physical drive needs to be partitioned with <tt>f_fdisk</tt> function or some partitioning tool prior to create the FAT volume with this function. If the partition is not exist, the function fails with <tt>FR_MKFS_ABORTED</tt>.</p>
<p>There are three standard disk partitioning formats, MBR, GPT and SFD. The MBR format, also known as FDISK format, is usually used for harddisk, memory card and U disk. It can divide a physical drive into one or more partitions with a partition table. The GPT, GUID Partition Table, is a newly defined patitioning format for large storage devices. FatFs suppors the GPT only when 64-bit LBA is enabled. The SFD, Super-Floppy Disk, is non-partitioned disk format. The FAT volume is located at LBA 0 and occupies the entire physical drive without any disk partitioning. It is usually used for floppy disk, optical disk and most super-floppy media. Some combination of systems and media support only either partitioned format or non-partitioned format and the other is not supported.</p>
<p>Some systems manage the partitions in the on-board storage in non-standard format. The partitions are mapped as physical drives identified by <tt class="arg">pdrv</tt> in <tt>disk_*</tt> functions. For such systems, SFD format is suitable to create the FAT volume in the partition.</p>
<p>There are three standard disk partitioning formats, MBR, GPT and SFD. The MBR format, also known as FDISK format, is usually used for harddisk, memory card and U disk. It can divide a physical drive into one or more partitions with a partition table. The GPT, GUID Partition Table, is a newly defined patitioning format for large storage devices. FatFs suppors the GPT only when 64-bit LBA is enabled. The SFD, Super-Floppy Disk, is non-partitioned disk format. The FAT volume is located at LBA 0 and occupies the entire physical drive without disk partitioning. It is usually used for floppy disk, optical disk and most super-floppy media. Some combination of systems and media support only either partitioned format or non-partitioned format and the other is not supported.</p>
<p>Some systems manage the partitions of on-board storage in non-standard format. The partitions are mapped as physical drives identified by <tt class="arg">pdrv</tt> in <tt>disk_*</tt> functions. For such systems, SFD format is suitable to create the FAT volume in the partition.</p>
</div>
<div class="para comp">