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FatFs R0.12a, released July 10, 2016

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Christopher Williams
2017-05-10 19:06:26 -07:00
parent 73b919bedf
commit 9798d01a6c
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doc/en/appnote.html
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@@ -42,9 +42,9 @@ The FatFs module assumes that size of <tt>char</tt>/<tt>short</tt>/<tt>long</tt>
<h4>System organizations</h4>
<p>The dependency diagram shown below is a typical but not specific configuration of the embedded system with FatFs module.</p>
<p><img src="../img/modules.png" width="580" height="280" alt="dependency diagram"></p>
<p><img src="../res/modules.png" width="580" height="280" alt="dependency diagram"></p>
<p>(a) If a working disk module with FatFs API is provided, no additional function is needed. (b) To attach existing disk drivers with different API, glue functions are needed to translate the APIs between FatFs and the drivers.</p>
<p><img src="../img/funcs.png" width="750" height="420" alt="functional diagram"></p>
<p><img src="../res/funcs.png" width="750" height="420" alt="functional diagram"></p>
<h4>Which function is required?</h4>
<p>You need to provide only low level disk I/O functions that required by FatFs module and nothing else. If a working disk module for the target system is already existing, you need to write only glue functions to attach it to the FatFs module. If not, you need to port any other disk module or write it from scratch. Most of defined functions are not that always required. For example, disk write function is not required at read-only configuration. Following table shows which function is required depends on the configuration options.</p>
@@ -69,7 +69,7 @@ The FatFs module assumes that size of <tt>char</tt>/<tt>short</tt>/<tt>long</tt>
<li>Number of volumes: Upto 10.</li>
<li>Volume size: Upto 2 TiB at 512 bytes/sector.</li>
<li>File size: Upto 4 GiB - 1 on FAT volume and virtually unlimited on exFAT volume.</li>
<li>Cluster size: Upto 128 sector on FAT volume, upto 32768 sectors on exFAT volume.</li>
<li>Cluster size: Upto 128 sectors on FAT volume and upto 16 MiB on exFAT volume.</li>
<li>Sector size: 512, 1024, 2048 and 4096 bytes.</li>
</ul>
</div>
@@ -144,7 +144,7 @@ And any other options are left unchanged from original setting.
<div class="para doc" id="lfn">
<h3>Long File Name</h3>
<p>FatFs module supports long file name (LFN). The two different file names, short file name (SFN) and LFN, of a file is transparent on the API except for <tt>f_readdir</tt> function. The support for LFN is disabled by default. To enable the LFN, set <tt><a href="config.html#use_lfn">_USE_LFN</a></tt> to 1, 2 or 3, and add <tt>option/unicode.c</tt> to the project. The LFN requiers a certain working buffer in addition. The buffer size can be configured by <tt><a href="config.html#max_lfn">_MAX_LFN</a></tt> according to the available memory. The length of an LFN will be up to 255 characters, so that the <tt>_MAX_LFN</tt> should be set to 255 for all file names. If the size of working buffer is insufficient for the input file name, the file function fails with <tt>FR_INVALID_NAME</tt>. When use any re-entry to the API with LFN is enabled, <tt>_USE_LFN</tt> must be set to 2 or 3. In this case, the file function allocates the working buffer on the stack or heap. The working buffer occupies <tt>(_MAX_LFN + 1) * 2</tt> bytes.</p>
<p>FatFs module supports long file name (LFN). The two different file names, short file name (SFN) and LFN, of a file is transparent on the API except for <tt>f_readdir</tt> function. The support for LFN is disabled by default. To enable the LFN, set <tt><a href="config.html#use_lfn">_USE_LFN</a></tt> to 1, 2 or 3, and add <tt>option/unicode.c</tt> to the project. The LFN requiers a certain working buffer in addition. The buffer size can be configured by <tt><a href="config.html#max_lfn">_MAX_LFN</a></tt> according to the available memory. The length of an LFN will be up to 255 characters, so that the <tt>_MAX_LFN</tt> should be set to 255 for all file names. If the size of working buffer is insufficient for the input file name, the file function fails with <tt>FR_INVALID_NAME</tt>. When use any re-entry to the API with LFN is enabled, <tt>_USE_LFN</tt> must be set to 2 or 3. In this case, the file function allocates the working buffer on the stack or heap. The working buffer occupies <tt>(_MAX_LFN + 1) * 2</tt> bytes and additional 608 bytes when exFAT enabled.</p>
<table class="lst2 rset">
<caption>With LFN at CM3+gcc</caption>
<tr><th><tt>_CODE_PAGE</tt></th><th>Code size</th></tr>
@@ -166,9 +166,9 @@ And any other options are left unchanged from original setting.
<div class="para doc" id="exfat">
<h3>exFAT File System</h3>
<p>The exFAT (Microsoft's Extended File Allocation Table) file system is a replacement of the FAT file system which has been widely used in the embedded systems and consumer devices. It is adopted by SDA (SD Association) as a recommended file system for high capacity SD cards (&gt;32GB) and they are being shipped with this format, so that the exFAT will soon become one of the standard file systems for removable media.</p>
<p>The exFAT file system allows the file size larger than 4 GiB limit what FAT file system allows upto and some file system overhead, especially file allocation delay, are reduced as well. This feature improves the write throughput to the file. However a problem on the current implementation of FatFs is that write throughput on the fragmented file with extension of size gets less than the throughput on the FAT volume. Pre-allocating a contiguous block with <tt>f_expand</tt> function may be a workaround of this problem.</p>
<p>The exFAT file system allows the file size larger than 4 GiB limit what FAT file system allows upto and some file system overhead, especially file allocation delay, are reduced as well. This feature improves the write throughput to the file. However a problem on the current implementation of FatFs is that write throughput at writing to the growing edge of the fragmented file gets less than the throughput on the FAT volume. Pre-allocating a contiguous block with <tt>f_expand</tt> function may be a workaround of this problem.</p>
<p>Note that the exFAT is a patent of Microsoft Corporation. The exFAT function of FatFs is an implementation based on US. Pat. App. Pub. No. 2009/0164440 A1. FatFs module can swich the exFAT on or off by configuration option. When enable the exFAT on the commercial products, you will need to be licensed by Microsoft depends on the final destination of the products.</p></div>
<p><em>Remark: Enabling exFAT discards C89 compatibility due to need for 64-bit integer type.</em></p>
<p><em>Remark: Enabling exFAT discards C89 compatibility because of need for 64-bit integer type.</em></p>
<div class="para doc" id="reentrant">
<h3>Re-entrancy</h3>
@@ -189,13 +189,13 @@ And any other options are left unchanged from original setting.
<h3>Performance Effective File Access</h3>
<p>For good read/write throughput on the small embedded systems with limited size of memory, application programmer should consider what process is done in the FatFs module. The file data on the volume is transferred in following sequence by <tt>f_read</tt> function.</p>
<p>Figure 1. Sector misaligned read (short)<br>
<img src="../img/f1.png" width="490" height="110" alt="">
<img src="../res/f1.png" width="490" height="110" alt="">
</p>
<p>Figure 2. Sector misaligned read (long)<br>
<img src="../img/f2.png" width="490" height="140" alt="">
<img src="../res/f2.png" width="490" height="140" alt="">
</p>
<p>Figure 3. Fully sector aligned read<br>
<img src="../img/f3.png" width="490" height="119" alt="">
<img src="../res/f3.png" width="490" height="119" alt="">
</p>
<p>The file I/O buffer is a sector buffer to read/write a part of data on the sector. The sector buffer is either file private sector buffer on each file object or shared sector buffer in the file system object. The buffer configuration option <tt><a href="config.html#fs_tiny">_FS_TINY</a></tt> determins which sector buffer is used for the file data transfer. When tiny buffer configuration (1) is selected, data memory consumption is reduced <tt>_MAX_SS</tt> bytes each file object. In this case, FatFs module uses only a sector buffer in the file system object for file data transfer and FAT/directory access. The disadvantage of the tiny buffer configuration is: the FAT data cached in the sector buffer will be lost by file data transfer and it must be reloaded at every cluster boundary. However it will be suitable for most application from view point of the decent performance and low memory comsumption.</p>
<p>Figure 1 shows that a partial sector, sector misaligned part of the file, is transferred via the file I/O buffer. At long data transfer shown in Figure 2, middle of transfer data that covers one or more sector is transferred to the application buffer directly. Figure 3 shows that the case of entier transfer data is aligned to the sector boundary. In this case, file I/O buffer is not used. On the direct transfer, the maximum extent of sectors are read with <tt>disk_read</tt> function at a time but the multiple sector transfer is divided at cluster boundary even if it is contiguous.</p>
@@ -208,12 +208,12 @@ And any other options are left unchanged from original setting.
<h4>Using Mutiple-Sector Write</h4>
<div class="rset">
Figure 6. Comparison between Multiple/Single Sector Write<br>
<img src="../img/f6.png" width="630" height="148" alt="fig.6">
<img src="../res/f6.png" width="630" height="148" alt="fig.6">
</div>
<p>The write throughput of the flash memory media becomes the worst at single sector write transaction. The write throughput increases as the number of sectors per a write transaction as shown in Figure 6. This effect more appers at faster interface speed and the performance ratio often becomes grater than ten. <a href="../img/rwtest2.png">This graph</a> is clearly explaining how fast is multiple block write (W:16K, 32 sectors) than single block write (W:100, 1 sector), and also larger card tends to be slow at single block write. Number of write transactions also affects life time of the flash memory media. When compared at same amount of write data, the single sector write in Figure 6 above wears flash memory media 16 times more than multiple sector write in Figure 6 below. Single sector write is pretty pain for the flash memory media.</p>
<p>The write throughput of the flash memory media becomes the worst at single sector write transaction. The write throughput increases as the number of sectors per a write transaction as shown in Figure 6. This effect more appers at faster interface speed and the performance ratio often becomes grater than ten. <a href="../res/rwtest2.png">This graph</a> is clearly explaining how fast is multiple block write (W:16K, 32 sectors) than single block write (W:100, 1 sector), and also larger card tends to be slow at single block write. Number of write transactions also affects life time of the flash memory media. When compared at same amount of write data, the single sector write in Figure 6 above wears flash memory media 16 times more than multiple sector write in Figure 6 below. Single sector write is pretty pain for the flash memory media.</p>
<p>Therefore the application program should write the data in large block as possible. The ideal write chunk size and alighment is size of sector, and size of cluster is the best. Of course all layers between the application and the storage device must have consideration on multiple sector write, however most of open-source memory card drivers lack it. Do not split a multiple sector write request into single sector write transactions or the write throughput gets poor. Note that FatFs module and its sample disk drivers supprt multiple sector read/write operation. </p>
<h4>Forcing Memory Erase</h4>
<p>When remove a file with <tt>f_remove</tt> function, the data clusters occupied by the file are marked 'free' on the FAT. But the data sectors containing the file data are not that applied any process, so that the file data left occupies a part of the flash memory array as 'live block'. If the file data is forced erased on removing the file, those data blocks will be turned in to the free block pool. This may skip internal block erase operation to the data block on next write operation. As the result the write performance might be improved. FatFs can manage this function by setting <tt><a href="config.html#use_trim">_USE_TRIM</a></tt> to 1. Note that this is an expectation of internal process of the flash memory storage and not that always effective. Also <tt>f_remove</tt> function will take a time when remove a large file. Most applications will not need this function.</p>
<p>When remove a file with <tt>f_unlink</tt> function, the data clusters occupied by the file are marked 'free' on the FAT. But the data sectors containing the file data are not that applied any process, so that the file data left occupies a part of the flash memory array as 'live block'. If the file data can be erased on removing the file, those data blocks will be turned into the free block pool. This may skip internal block erase operation to the data block on next write operation. As the result the write performance might be improved. FatFs can manage this function by setting <tt><a href="config.html#use_trim">_USE_TRIM</a></tt> to 1. Note that this is an expectation of internal process of the storage device and not that always effective. Most applications will not need this function. Also <tt>f_unlink</tt> function can take a time when remove a large file.</p>
</div>
<div class="para doc" id="critical">
@@ -221,11 +221,11 @@ Figure 6. Comparison between Multiple/Single Sector Write<br>
<p>If a write operation to the FAT volume is interrupted due to any accidental failure, such as sudden blackout, incorrect media removal and unrecoverable disk error, the FAT structure on the volume can be broken. Following images shows the critical section of the FatFs module.</p>
<div class="lset">
Figure 4. Long critical section<br>
<img src="../img/f4.png" width="320" height="436" alt="fig.4">
<img src="../res/f4.png" width="320" height="436" alt="fig.4">
</div>
<div class="lset">
Figure 5. Minimized critical section<br>
<img src="../img/f5.png" width="320" height="436" alt="fig.5">
<img src="../res/f5.png" width="320" height="436" alt="fig.5">
</div>
<br class="clr">
<p>An interruption in the red section can cause a cross link; as a result, the object being changed can be lost. If an interruption in the yellow section is occured, there is one or more possibility listed below.</p>
@@ -243,11 +243,11 @@ Figure 5. Minimized critical section<br>
<h3>Extended Use of FatFs API</h3>
<p>These are examples of extended use of FatFs APIs. New item will be added whenever a useful code is found.</p>
<ol>
<li><a href="../img/app1.c">Open or create a file for append</a></li>
<li><a href="../img/app2.c">Empty a directory</a></li>
<li><a href="../img/app3.c">Allocate contiguous area to the file</a> (R0.11a and older)</li>
<li><a href="../img/app4.c">Function/Compatible checker for low level disk I/O module</a></li>
<li><a href="../img/mkfatimg.zip">FAT image creator</a></li>
<li><a href="../res/app1.c">Open or create a file for append</a> (for R0.12 and older)</li>
<li><a href="../res/app2.c">Empty a directory</a></li>
<li><a href="../res/app3.c">Allocate contiguous area to the file</a> (for R0.11a and older)</li>
<li><a href="../res/app4.c">Function/compatibility checker for low level disk I/O module</a></li>
<li><a href="../res/mkfatimg.zip">FAT image creator</a></li>
</ol>
</div>
@@ -256,13 +256,15 @@ Figure 5. Minimized critical section<br>
<p>FatFs has being developped as a personal project of the author, ChaN. It is free from the code anyone else wrote at current release. Following code block shows a copy of the FatFs license document that included in the source files.</p>
<pre>
/*----------------------------------------------------------------------------/
/ FatFs - FAT file system module R0.12 (C)ChaN, 2016
/ FatFs - Generic FAT file system module R0.12a /
/-----------------------------------------------------------------------------/
/ FatFs module is a free software that opened under license policy of
/ following conditions.
/
/ Copyright (C) 2016, ChaN, all right reserved.
/
/ FatFs module is an open source software. Redistribution and use of FatFs in
/ source and binary forms, with or without modification, are permitted provided
/ that the following condition is met:
/ 1. Redistributions of source code must retain the above copyright notice,
/ this condition and the following disclaimer.
/
@@ -272,7 +274,7 @@ Figure 5. Minimized critical section<br>
/ by use of this software.
/----------------------------------------------------------------------------*/
</pre>
<p>Therefore FatFs license is one of the BSD-style licenses but there is a significant feature. FatFs is mainly intended for embedded systems. In order to extend the usability for commercial products, the redistributions of FatFs in binary form, such as embedded code or any forms without source code, does not need to explain about use of FatFs in the documentations. This is equivalent to the 1-clause BSD license. Of course FatFs is compatible with the most open source software licenses including GNU GPL. When you redistribute the FatFs source code with any modification or create a fork, the license can also be changed to GNU GPL, BSD-style license or any open source software licenses that not conflict with FatFs license.</p>
<p>Therefore FatFs license is one of the BSD-style licenses but there is a significant feature. FatFs is mainly intended for embedded systems. In order to extend the usability for commercial products, the redistributions of FatFs in binary form, such as embedded code, binary library and any forms without source code, does not need to include about FatFs in the documentations. This is equivalent to the 1-clause BSD license. Of course FatFs is compatible with the most open source software licenses including GNU GPL. When you redistribute the FatFs source code with any changes or create a fork, the license can also be changed to GNU GPL, BSD-style license or any open source software licenses that not conflict with FatFs license.</p>
</div>
<p class="foot"><a href="../00index_e.html">Return Home</a></p>
doc/en/close.html
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@@ -45,7 +45,7 @@ FRESULT f_close (
<div class="para desc">
<h4>Description</h4>
<p>The <tt>f_close</tt> function closes an open file object. If any data has been written to the file, the cached information of the file is written back to the volume. After the function succeeded, the file object is no longer valid and it can be discarded.</p>
<p>Note that if the file object is in read-only mode and <tt>_FS_LOCK</tt> option is not enabled, the file object can also be discarded without this process. However this is not recommended for future compatibility.</p>
<p>Note that if the file object is in read-only mode and <tt>_FS_LOCK</tt> is not enabled, the file object can also be discarded without this process. However this is not recommended for future compatibility.</p>
</div>
doc/en/config.html
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@@ -57,7 +57,7 @@
<p>Disable (0) or Enable (1) volume label functions, <tt>f_getlabel</tt> and <tt>f_setlabel</tt>.</p>
<h4 id="use_forward">_USE_FORWARD</h4>
<p>Disable (0) or Enable (1) <tt>f_forward</tt> function. Also <tt>_FS_TINY</tt> needs to be 1.</p>
<p>Disable (0) or Enable (1) <tt>f_forward</tt> function.</p>
</div>
@@ -172,13 +172,13 @@
<p>Normal (0) or Tiny (1). At the tiny configuration, size of the file object <tt>FIL</tt> is reduced <tt>_MAX_SS</tt> bytes. Instead of private data buffer eliminated from the file object, common sector buffer in the file system object <tt>FATFS</tt> is used for the file data transfer.</p>
<h4 id="fs_exfat">_FS_EXFAT</h4>
<p>This option switches support for the exFAT file system in addition to the FAT file system, Enabled(1) or Disabled(1). To enable the exFAT, also LFN must be enabled. When enable exFAT, configureing <tt>_LFN_UNICODE = 1</tt> and <tt>_MAX_LFN = 255</tt> is recommended for full-featured exFAT function. Note that enabling exFAT discards C89 compatibility due to need for 64-bit integer type.</p>
<p>This option switches support for the exFAT file system in addition to the FAT file system, Enabled(1) or Disabled(1). To enable this feature, also LFN must be enabled and configureing <tt>_LFN_UNICODE = 1</tt> and <tt>_MAX_LFN = 255</tt> is recommended for full-featured exFAT function. Note that enabling exFAT discards C89 compatibility because of need for 64-bit integer type.</p>
<h4 id="fs_nortc">_FS_NORTC</h4>
<p>Use RTC (0) or Do not use RTC (1). This option controls timestamp function. If the system does not have an RTC function or valid timestamp is not needed, set <tt>_FS_NORTC</tt> to 1 to disable the timestamp function. Any object modified by FatFs will have a fixed timestamp value defined by <tt>_NORTC_MON</tt>, <tt>_NORTC_MDAY</tt> and <tt>_NORTC_YEAR</tt>. To use the timestamp function, set <tt>_FS_NORTC = 0</tt> and add <tt>get_fattime</tt> function to the project to get the current time form real-time clock. This option has no effect at read-only configuration.</p>
<h4 id="nortc_time">_NORTC_MON, _NORTC_MDAY, _NORTC_YEAR</h4>
<p>This set of options defines default timestamp to be used at no RTC systems. This option has no effect at read-only configuration or <tt>_FS_NORTC = 0</tt>.</p>
<p>This set of options defines the time to be used at no RTC systems. This option has no effect at read-only configuration or <tt>_FS_NORTC = 0</tt>.</p>
<h4 id="fs_lock">_FS_LOCK</h4>
<p>This option switches file lock function to control duplicated file open and illegal operations to open objects. Note that the file lock function is independent of re-entrancy. This option must be 0 at read-only configuration.</p>
@@ -189,7 +189,7 @@
</table>
<h4 id="fs_reentrant">_FS_REENTRANT</h4>
<p>Disable (0) or Enable (1). This option switches the re-entrancy (thread safe) of the FatFs module itself. Note that file/directory access to the different volume is always re-entrant and it can work simultaneously regardless of this option but volume control functions, <tt>f_mount</tt>, <tt>f_mkfs</tt> and <tt>f_fdisk</tt>, are always not re-entrant. Only file/directory access to the same volume, in other words, exclusive use of each file system object, is under control of this function. To enable this function, also user provided synchronization handlers, <tt>ff_req_grant</tt>, <tt>ff_rel_grant</tt>, <tt>ff_del_syncobj</tt> and <tt>ff_cre_syncobj</tt>, need to be added to the project. Sample code is available in <tt>option/syscall.c</tt>.</p>
<p>Disable (0) or Enable (1). This option switches the re-entrancy (thread safe) of the FatFs module itself. Note that file/directory access to the different volume is always re-entrant and it can work simultaneously regardless of this option but volume control functions, <tt>f_mount</tt>, <tt>f_mkfs</tt> and <tt>f_fdisk</tt>, are always not re-entrant. Only file/directory access to the same volume, in other words, exclusive use of each file system object, is under control of this function. To enable this feature, also user provided synchronization handlers, <tt>ff_req_grant</tt>, <tt>ff_rel_grant</tt>, <tt>ff_del_syncobj</tt> and <tt>ff_cre_syncobj</tt>, need to be added to the project. Sample code is available in <tt>option/syscall.c</tt>.</p>
<h4 id="fs_timeout">_FS_TIMEOUT</h4>
<p>Number of time ticks to abort the file function with <tt>FR_TIMEOUT</tt> when wait time is too long. This option has no effect when <tt>_FS_REENTRANT = 0</tt>.</p>
doc/en/expand.html
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@@ -13,7 +13,7 @@
<div class="para func">
<h2>f_expand</h2>
<p>The f_expand function prepare or allocates a contiguous data area to the file.</p>
<p>The f_expand function prepares or allocates a contiguous data area to the file.</p>
<pre>
FRESULT f_expand (
@@ -30,7 +30,7 @@ FRESULT f_expand (
<dt>fp</dt>
<dd>Pointer to the open file object.</dd>
<dt>fsz</dt>
<dd>Number of bytes in size to prepare or be allocated to the file. The data type <tt>FSIZE_t</tt> is an alias of either <tt>DWORD</tt>(32-bit) or <tt>QWORD</tt>(64-bit) depends on the configuration option <tt>_FS_EXFAT</tt>.</dd>
<dd>Number of bytes in size to prepare or allocate for the file. The data type <tt>FSIZE_t</tt> is an alias of either <tt>DWORD</tt>(32-bit) or <tt>QWORD</tt>(64-bit) depends on the configuration option <tt>_FS_EXFAT</tt>.</dd>
<dt>opt</dt>
<dd>Operation mode. Prepare only (0) or Allocate now (1).</dd>
</dl>
@@ -52,16 +52,16 @@ FRESULT f_expand (
<div class="para desc">
<h4>Description</h4>
<p>The <tt>f_expand</tt> function prepare or allocates a contiguous data area to the file. When <tt class="arg">opt</tt> is 1, the function allocates a contiguous data area to the file. Unlike file expansion of file by <tt>f_lseek</tt> function, the file must be truncated prior to use this function and read/write pointer of the file stays at top of the file after the function. The file content allocated with this function is undefined. The function can be failed with <tt>FR_DENIED</tt> due to some reasons below.</p>
<p>The <tt>f_expand</tt> function prepares or allocates a contiguous data area to the file. When <tt class="arg">opt</tt> is 1, the function allocates a contiguous data area to the file. Unlike expansion of file by <tt>f_lseek</tt> function, the file must be truncated prior to use this function and read/write pointer of the file stays at top of the file after the function. The file content allocated with this function is <em>undefined</em> because no data is written to the file in this process. The function can fail with <tt>FR_DENIED</tt> due to some reasons below.</p>
<ul>
<li>No free contiguous space for the file was found.</li>
<li>Size of the file was not zero on expand.</li>
<li>No free contiguous space was found.</li>
<li>Size of the file was not zero.</li>
<li>The file has been opened in read-only mode.</li>
<li>Not allowable file size. (&gt;= 4GiB on FAT volume)</li>
</ul>
<p>When <tt class="arg">opt</tt> is 0, the function finds a contiguous data area and set it as suggested allocation point instead of allocating it to the file. The next cluster allocation is started at top of the contiguous data area. Thus the write file is guaranteed be contiguous and no allocation delay at least until the size reaches that size unless any other operation to the volume with changes of FAT is performed.</p>
<p>The contiguous file would have an advantage at time-critical read/write operations. It reduces some overheads in the file system and the storage media caused by random access due to fragmented file data. Especially at the exFAT volume, any FAT access for the contiguous file is completely eliminated and storage media will be accessed sequentially.</p>
<p>Also the contiguous file data can be accessed directory via low-level disk functions but it is not recommended in consideration for future compatibility.</p>
<p>When <tt class="arg">opt</tt> is 0, the function finds a contiguous data area and set it as suggested point for next allocation instead of allocating it to the file. The next cluster allocation is started at top of the contiguous area found by this function. Thus the write file is guaranteed be contiguous and no allocation delay until the size reaches that size at least unless any other operation to the volume with changes of FAT is performed.</p>
<p>The contiguous file would have an advantage at time-critical read/write operations. It reduces some overheads in the file system and the storage media caused by random access due to fragmented file data. Especially, at the exFAT volume, any FAT access for the contiguous file is completely eliminated and storage media will be accessed sequentially.</p>
<p>Also the contiguous file data can be easily accessed directly via low-level disk functions but it is not recommended in consideration for future compatibility.</p>
</div>
<div class="para comp">
@@ -85,6 +85,7 @@ FRESULT f_expand (
<span class="c">/* Alloacte a 100 MiB of contiguous area to the file */</span>
res = f_expand(fp, 104857600, 1);
if (res) { <span class="c">/* Check if the file has been expanded */</span>
...
free(fp);
...
}
doc/en/fdisk.html
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@@ -16,9 +16,9 @@
<p>The f_fdisk fucntion divides a physical drive.</p>
<pre>
FRESULT f_fdisk (
BYTE <span class="arg">pdrv</span>, <span class="c">/* [IN] Physical drive number */</span>
const DWORD <span class="arg">part[]</span>, <span class="c">/* [IN] Partition size */</span>
void* <span class="arg">work</span> <span class="c">/* [IN] Work area */</span>
BYTE <span class="arg">pdrv</span>, <span class="c">/* [IN] Physical drive number */</span>
const DWORD* <span class="arg">szt</span>, <span class="c">/* [IN] Partition map table */</span>
void* <span class="arg">work</span> <span class="c">/* [IN] Work area */</span>
);
</pre>
</div>
@@ -27,9 +27,9 @@ FRESULT f_fdisk (
<h4>Parameters</h4>
<dl class="par">
<dt>pdrv</dt>
<dd>Specifies the <em>physical drive</em> to be divided.</dd>
<dt>part[]</dt>
<dd>Partition map table. It must have four items.</dd>
<dd>Specifies the <em>physical drive</em> to be divided. This is not the logical drive number but the drive identifier passed to the low level disk functions.</dd>
<dt>szt</dt>
<dd>Pointer to the first item of the partition map table.</dd>
<dt>work</dt>
<dd>Pointer to the function work area. The size must be at least <tt>_MAX_SS</tt> bytes.</dd>
</dl>
@@ -48,7 +48,7 @@ FRESULT f_fdisk (
<div class="para desc">
<h4>Description</h4>
<p>The <tt>f_fdisk</tt> function creates a partition table into the MBR of the physical drive. The partitioning rule is in generic FDISK format, so that it can create upto four primary partitions. Logical volumes in the extended partition is not supported. The <tt class="arg">part[]</tt> with four items specifies how to divide the physical drive. The first item specifies the size of first primary partition and fourth item specifies the fourth primary partition. If the value is less than or equal to 100, it specifies percentage of the partition in the entire disk space. If it is larger than 100, it specifies the partition size in unit of sector.</p>
<p>The <tt>f_fdisk</tt> function creates partitions on the physical drive. The partitioning format is in generic FDISK format, so that it can create upto four primary partitions. Logical volumes in the extended partition is not supported. The partition map table with four items specifies how to divide the physical drive. The first item specifies the size of first primary partition and fourth item specifies the fourth primary partition. If the value is less than or equal to 100, it specifies the partition size in percentage of the entire drive space. If it is larger than 100, it specifies the partition size in unit of sector. The partitions are located on the drive in order of from first item.</p>
</div>
<div class="para comp">
@@ -74,15 +74,10 @@ FRESULT f_fdisk (
DWORD plist[] = {50, 50, 0, 0}; <span class="c">/* Divide drive into two partitions */</span>
BYTE work[_MAX_SS];
f_fdisk(0, plist, work); <span class="c">/* Divide physical drive 0 */</span>
f_fdisk(0, plist, work); <span class="c">/* Divide physical drive 0 */</span>
f_mount(&amp;fs, "0:", 0); <span class="c">/* Register work area to the logical drive 0 */</span>
f_mkfs("0:", 0, 0); <span class="c">/* Create FAT volume on the logical drive 0. 2nd argument is ignored. */</span>
f_mount(0, "0:", 0); <span class="c">/* Unregister work area from the logical drive 0 */</span>
f_mount(&amp;fs, "1:", 0); <span class="c">/* Register a work area to the logical drive 1 */</span>
f_mkfs("1:", 0, 0); <span class="c">/* Create FAT volume on the logical drive 1. 2nd argument is ignored. */</span>
f_mount(0, "1:", 0); <span class="c">/* Unregister work area from the logical drive 1 */</span>
f_mkfs("0:", FMT_ANY, work, sizeof work); <span class="c">/* Create FAT volume on the logical drive 0 */</span>
f_mkfs("1:", FMT_ANY, work, sizeof work); <span class="c">/* Create FAT volume on the logical drive 1 */</span>
</pre>
</div>
doc/en/filename.html
+10 -10
View File
@@ -35,7 +35,7 @@
<tr><td>dir1/..</td><td>Invalid name</td><td>The current directory</td></tr>
<tr><td>/..</td><td>Invalid name</td><td>The root directory (sticks the top level)</td></tr>
</table>
<p>When option <tt><a href="config.html#str_volume_id">_STR_VOLUME_ID</a></tt> is specified, also pre-defined strings can be used as drive identifier in the path name instead of a numeral. e.g. <tt>"sd:file1.txt"</tt> or <tt>"ram:swapfile.dat"</tt>.</p>
<p>When option <tt><a href="config.html#str_volume_id">_STR_VOLUME_ID</a></tt> is specified, also pre-defined strings can be used as drive identifier in the path name instead of a numeral. e.g. <tt>"sd:file1.txt"</tt>, <tt>"ram:swapfile.dat"</tt> and DOS/Windows style drive letter, of course.</p>
<p><em>Remark: In this revision, R0.12, double dot name <tt>".."</tt> cannot follow the parent directory on the exFAT volume. It will work as <tt>"."</tt> and stay there.</em></p>
</div>
@@ -58,25 +58,25 @@
<div class="para doc" id="vol">
<h3>Volume Management</h3>
<p>The FatFs module needs dynamic work area called <em>file system object</em> for each volume (logical drive). It is registered to the FatFs module by <tt>f_mount</tt> function. By default, each logical drive is bound to the physical drive with the same drive number and an FAT volume on the drive is serched by volume mount process. It loads boot sectors and checks it if it is an FAT boot sector in order of sector 0 as SFD format, 1st partition, 2nd partition, 3rd partition and 4th partition as FDISK format.</p>
<p>FatFs module needs dynamic work area, <em>file system object</em>, for each volume (logical drive). It is registered/unregistered to the FatFs module by <tt>f_mount</tt> function. By default, each logical drive is bound to the physical drive with the same drive number and an FAT volume on the drive is serched by the volume mount process. It reads boot sectors and checks it if it is an FAT boot sector in order of sector 0 as SFD format, 1st partition, 2nd partition, 3rd partition and 4th partition as FDISK format.</p>
<p>When <tt><a href="config.html#multi_partition">_MULTI_PARTITION</a> == 1</tt> is specified by configuration option, each individual logical drive is bound to the partition on the physical drive specified by volume management table. The volume management table must be defined by user to resolve the relationship between logical drives and partitions. Following code is an example of a volume management table.</p>
<pre>
Example: Logical drive 0-2 are tied to three pri-partitions on the physical drive 0 (fixed disk)
Logical drive 3 is tied to an FAT volume on the physical drive 1 (removable disk)
Example: Logical drive 0-2 are tied to three pri-partitions on the physical drive 0 (fixed drive)
Logical drive 3 is tied to an FAT volume on the physical drive 1 (removable drive)
PARTITION VolToPart[] = {
{0, 1}, <span class="c">/* Logical drive 0 ==> Physical drive 0, 1st partition */</span>
{0, 2}, <span class="c">/* Logical drive 1 ==> Physical drive 0, 2nd partition */</span>
{0, 3}, <span class="c">/* Logical drive 2 ==> Physical drive 0, 3rd partition */</span>
{1, 0} <span class="c">/* Logical drive 3 ==> Physical drive 1 (auto detection) */</span>
{0, 1}, <span class="c">/* "0:" ==> Physical drive 0, 1st partition */</span>
{0, 2}, <span class="c">/* "1:" ==> Physical drive 0, 2nd partition */</span>
{0, 3}, <span class="c">/* "2:" ==> Physical drive 0, 3rd partition */</span>
{1, 0} <span class="c">/* "3:" ==> Physical drive 1, auto detection */</span>
};
</pre>
<div><img src="../img/f7.png" width="828" height="288" alt="relationship between logical drive and physical drive"></div>
<div><img src="../res/f7.png" width="828" height="288" alt="relationship between logical drive and physical drive"></div>
<p>There are some considerations on using multi-partition configuration.</p>
<ul>
<li>The physical drive that has two or more mounted partitions must be non-removable. Media change while a system operation is prohibited.</li>
<li>Only four primary partitions can be specified. Extended partition is not supported.</li>
<li>Windows does not support multiple volumes on the removable storage. Only first parition will be mounted.</li>
<li>Windows does not support multiple volumes on the removable storage. Only first parition will be recognized.</li>
</ul>
</div>
doc/en/findfirst.html
+2 -2
View File
@@ -66,14 +66,14 @@ FRESULT f_findfirst (
<ul>
<li><tt>"*.*"</tt> never matches any name without extension while it matches any names at the standard systems.</li>
<li>Any patterns terminated with a period never matches any name while it matches any names without extensiton at the standard systems.</li>
<li><a href="filename.html#case">DBCS extended characters</a> are compared in case-sensitive at LFN and non-Unicode configuration.</li>
<li><a href="filename.html#case">DBCS extended characters</a> are compared in case-sensitive at LFN with non-Unicode configuration.</li>
</ul>
</div>
<div class="para comp">
<h4>QuickInfo</h4>
<p>This is a wrapper function of <a href="opendir.html"><tt>f_opendir</tt></a> and <a href="readdir.html"><tt>f_readdir</tt></a> function. Available when <tt>_USE_FIND &lt;= 1</tt> and <tt>_FS_MINIMIZE &lt;= 1</tt>.</p>
<p>This is a wrapper function of <a href="opendir.html"><tt>f_opendir</tt></a> and <a href="readdir.html"><tt>f_readdir</tt></a> function. Available when <tt>_USE_FIND &gt;= 1</tt> and <tt>_FS_MINIMIZE &lt;= 1</tt>.</p>
</div>
doc/en/forward.html
+1 -1
View File
@@ -59,7 +59,7 @@ FRESULT f_forward (
<div class="para comp">
<h4>QuickInfo</h4>
<p>Available when <tt>_USE_FORWARD == 1</tt> and <tt>_FS_TINY == 1</tt>.</p>
<p>Available when <tt>_USE_FORWARD == 1</tt>.</p>
</div>
doc/en/getlabel.html
+1 -1
View File
@@ -29,7 +29,7 @@ FRESULT f_getlabel (
<dt>path</dt>
<dd>Pointer to the null-terminated string that specifies the <a href="filename.html">logical drive</a>. Null-string specifies the default drive.</dd>
<dt>label</dt>
<dd>Pointer to the buffer to store the volume label. The buffer size must be at least 24 items at <tt>_LFN_UNICODE == 0</tt>, 12 items at <tt>_LFN_UNICODE == 1</tt>. If the volume has no label, a null-string will be returned. Set null pointer if this information is not needed.</dd>
<dd>Pointer to the buffer to store the volume label. The buffer size must be at least 24 items at <tt>_LFN_UNICODE == 0</tt> or 12 items at <tt>_LFN_UNICODE == 1</tt>. If the volume has no label, a null-string will be returned. Set null pointer if this information is not needed.</dd>
<dt>vsn</dt>
<dd>Pointer to the <tt>DWORD</tt> variable to store the volume serial number. Set null pointer if this information is not needed.</dd>
</dl>
doc/en/lseek.html
+1 -1
View File
@@ -48,7 +48,7 @@ FRESULT f_lseek (
<div class="para desc">
<h4>Description</h4>
<p>The <tt>f_lseek</tt> function moves the file read/write pointer of an open file. The offset can be specified in only origin from top of the file. When an offset beyond the file size is specified at write mode, the file size is expanded to the specified offset. The file data in the expanded area is undefined because no data is written to the file. This is suitable to pre-allocate a cluster chain quickly, for fast write operation. When a contiguous data area needs to be allocated to the file, use <tt>f_expand</tt> function instead. After the <tt>f_lseek</tt> function succeeded, the current read/write pointer should be checked in order to make sure the read/write pointer has been moved correctry. In case of the read/write pointer is not the expected value, either of followings has been occured.</p>
<p>The <tt>f_lseek</tt> function moves the file read/write pointer of an open file. The offset can be specified in only origin from top of the file. When an offset beyond the file size is specified at write mode, the file size is expanded to the specified offset. The file data in the expanded area is <em>undefined</em> because no data is written to the file in this process. This is suitable to pre-allocate a cluster chain quickly, for fast write operation. When a contiguous data area needs to be allocated to the file, use <tt>f_expand</tt> function instead. After the <tt>f_lseek</tt> function succeeded, the current read/write pointer should be checked in order to make sure the read/write pointer has been moved correctry. In case of the read/write pointer is not the expected value, either of followings has been occured.</p>
<ul>
<li>End of file. The specified <tt class="arg">ofs</tt> was clipped at end of the file because the file has been opened in read-only mode.</li>
<li>Disk full. There is no free space on the volume to expand the file.</li>
doc/en/mkfs.html
+31 -23
View File
@@ -13,12 +13,14 @@
<div class="para func">
<h2>f_mkfs</h2>
<p>The f_mkfs fucntion creates an FAT volume on the logical drive.</p>
<p>The f_mkfs fucntion creates an FAT/exFAT volume on the logical drive.</p>
<pre>
FRESULT f_mkfs (
const TCHAR* <span class="arg">path</span>, <span class="c">/* [IN] Logical drive number */</span>
BYTE <span class="arg">sfd</span>, <span class="c">/* [IN] Partitioning rule */</span>
UINT <span class="arg">au</span> <span class="c">/* [IN] Size of the allocation unit */</span>
BYTE <span class="arg">opt</span>, <span class="c">/* [IN] Format options */</span>
DWORD <span class="arg">au</span>, <span class="c">/* [IN] Size of the allocation unit */</span>
void* <span class="arg">work</span>, <span class="c">/* [-] Working buffer */</span>
UINT <span class="arg">len</span> <span class="c">/* [IN] Size of working buffer */</span>
);
</pre>
</div>
@@ -27,11 +29,15 @@ FRESULT f_mkfs (
<h4>Parameters</h4>
<dl class="par">
<dt>path</dt>
<dd>Pointer to the null-terminated string that specifies the <a href="filename.html">logical drive</a> to be formatted. If there is no drive number, it means the default drive.</dd>
<dt>sfd</dt>
<dd>Specifies partitioning rule, FDISK format (0) or SFD format (1). This argument will be ignored on some case.</dd>
<dd>Pointer to the null-terminated string specifies the <a href="filename.html">logical drive</a> to be formatted. If there is no drive number in it, it means the default drive. The logical drive does not need to be mounted.</dd>
<dt>opt</dt>
<dd>Specifies the format option in combination of <tt>FM_FAT</tt>, <tt>FM_FAT32</tt>, <tt>FM_EXFAT</tt> and bitwise-or of these three, <tt>FM_ANY</tt>. <tt>FM_EXFAT</tt> is ignored when exFAT is not enabled. These flags specify which FAT type to be created on the volume. If two or more types are specified, one out of them will be selected depends on the volume size. The flag <tt>FM_SFD</tt> specifies to place the volume on the drive in SFD format.</dd>
<dt>au</dt>
<dd>Specifies size of the allocation unit (cluter) in number of bytes or sectors. When the value is from 1 to 128, it specifies it in number of sectors. When the value is <tt>&gt;= _MIN_SS</tt>, it specifies it in number of bytes. If any invalid value, zero or not power of 2, is given, the cluster size is automatically determined depends on the volume size.</dd>
<dd>Specifies size of the allocation unit (cluter) in unit of byte. The valid value is N times the sector size. N is power of 2 from 1 to 128 for FAT volume and upto 16MiB for exFAT volume. If zero is given, the default allocation unit size is selected depends on the volume size.</dd>
<dt>work</dt>
<dd>Pointer to the working buffer for the format process.</dd>
<dt>len</dt>
<dd>Size of the working buffer in unit of byte. It needs to be the sector size at least. Plenty of working buffer reduces number of write transaction to the device and the format process will be finished quickly.</dd>
</dl>
</div>
@@ -43,7 +49,6 @@ FRESULT f_mkfs (
<a href="rc.html#nr">FR_NOT_READY</a>,
<a href="rc.html#wp">FR_WRITE_PROTECTED</a>,
<a href="rc.html#id">FR_INVALID_DRIVE</a>,
<a href="rc.html#ne">FR_NOT_ENABLED</a>,
<a href="rc.html#ma">FR_MKFS_ABORTED</a>,
<a href="rc.html#ip">FR_INVALID_PARAMETER</a>
</p>
@@ -51,11 +56,11 @@ FRESULT f_mkfs (
<div class="para desc">
<h4>Description</h4>
<p>The <tt>f_mkfs</tt> function creates an FAT volume on the specified logical drive. When FDISK format is specified, a primary partition occupies entire space of the physical drive and then an FAT volume is created on the partition. When SFD format is specified, the FAT volume starts from the first sector of the physical drive.</p>
<p>There are two partitioning rules, FDISK and SFD. The FDISK partitioning is usually used for harddisk, MMC, SDC, CFC and U Disk. It can divide a physical drive into one or more partitions with a partition table on the MBR. However Windows does not support multiple partition on the removable drive. The SFD is non-partitioned method. The FAT volume starts from the first sector on the physical drive without partition table. It is usually used for floppy disk, Microdrive, optical disk and any type of super-floppy media.</p>
<p>If the logical drive to be formatted is bound to the specific partition (1-4) by support of multiple partition, <tt><a href="config.html#multi_partition">_MULTI_PARTITION</a></tt>, the FAT volume is created into the partition. In this case, the second argument <tt class="arg">sfd</tt> has no effect. The physical drive must have been partitioned with <tt>f_fdisk</tt> function or any other partitioning tools prior to create the FAT volume with this function.</p>
<p>The FAT sub-type, FAT12/FAT16/FAT32, is determined by only number of clusters on the volume, according to the FAT specification issued by Microsoft. Thus which FAT sub-type is selected, is depends on the volume size and the specified cluster size. The cluster size affects read/write throughput and space usage efficiency. Larger cluster size increases the read/write throughput and decreases the space usage efficiency of the volume. In case of the number of clusters comes on the FAT sub-type boundaries, the function can fail with <tt>FR_MKFS_ABORTED</tt>.</p>
<p><em>Remark: Creating exFAT volume is not supported at current revision, R0.12.</em></p>
<p>The FAT sub-type, FAT12/FAT16/FAT32, of FAT volume except exFAT is determined by only number of clusters on the volume and nothing else, according to the FAT specification issued by Microsoft. Thus which FAT sub-type is selected, is depends on the volume size and the specified cluster size. In case of the combination of FAT type and cluter size specified by argument cannot be valid on the volume, the function will fail with <tt>FR_MKFS_ABORTED</tt>.</p>
<p>The allocation unit, also called 'cluster', 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 as the size of allocation unit. Therefore the allocation unit is a trade-off between space efficiency and performance. For the large storages in GB order, 32768 bytes or larger cluster (this is automatically selected by default) is recommended for most case unless extremely many files are created on a volume.</p>
<p>There are two disk formats, FDISK and SFD. The FDISK format is usually used for harddisk, MMC, SDC, CFC and U Disk. It can divide a physical drive into one or more partitions with a partition table on the MBR (maser boot record, the first sector of the physical drive). The SFD (super-floppy disk) is non-partitioned disk format. The FAT volume starts at the first sector of the physical drive without any disk partitioning. It is usually used for floppy disk, Microdrive, optical disk and most type of super-floppy media. Some systems support only either one of two formats and other is not supported.</p>
<p>When <tt>FM_SFD</tt> is not specified, a primary partition occupies whole drive space is created and then the FAT volume is created in it. When <tt>FM_SFD</tt> is specified, the FAT volume occupies from the first sector of the drive is created.</p>
<p>If the logical drive to be formatted is bound to the specific partition (1-4) by support of multiple partition, <tt><a href="config.html#multi_partition">_MULTI_PARTITION</a></tt>, the FAT volume is created into the partition and <tt>FM_SFD</tt> flag is ignored. The physical drive needs to be partitioned with <tt>f_fdisk</tt> function or any other partitioning tools prior to create the FAT volume with this function.</p>
</div>
<div class="para comp">
@@ -69,19 +74,20 @@ FRESULT f_mkfs (
<span class="c">/* Format default drive and create a file */</span>
int main (void)
{
FATFS fs; <span class="c">/* File system object (volume work area) */</span>
FIL fil; <span class="c">/* File object */</span>
FRESULT res; <span class="c">/* API result code */</span>
UINT bw; <span class="c">/* Bytes written */</span>
FATFS fs; <span class="c">/* File system object */</span>
FIL fil; <span class="c">/* File object */</span>
FRESULT res; <span class="c">/* API result code */</span>
UINT bw; <span class="c">/* Bytes written */</span>
BYTE work[_MAX_SS]; <span class="c">/* Work area (larger is better for process time) */</span>
<span class="c">/* Register work area (do not care about error) */</span>
f_mount(&amp;fs, "", 0);
<span class="c">/* Create FAT volume with default cluster size */</span>
res = f_mkfs("", 0, 0);
<span class="c">/* Create FAT volume */</span>
res = f_mkfs("", FM_ANY, 0, work, sizeof work);
if (res) ...
<span class="c">/* Register work area */</span>
f_mount(&amp;fs, "", 0);
<span class="c">/* Create a file as new */</span>
res = f_open(&amp;fil, "hello.txt", FA_CREATE_NEW | FA_WRITE);
if (res) ...
@@ -95,12 +101,14 @@ int main (void)
<span class="c">/* Unregister work area */</span>
f_mount(0, "", 0);
...
</pre>
</div>
<div class="para ref">
<h4>See Also</h4>
<p><tt><a href="filename.html#vol">Volume management</a>, <a href="fdisk.html">f_fdisk</a></tt></p>
<p><a href="../res/mkfs.xls">Example of volume size and format parameters</a>, <a href="filename.html#vol">Volume management</a>, <tt><a href="fdisk.html">f_fdisk</a></tt></p>
</div>
<p class="foot"><a href="../00index_e.html">Return</a></p>
doc/en/open.html
+5 -5
View File
@@ -33,14 +33,14 @@ FRESULT f_open (
<dt>mode</dt>
<dd>Mode flags that specifies the type of access and open method for the file. It is specified by a combination of following flags.<br>
<table class="lst">
<tr><th>Value</th><th>Description</th></tr>
<tr><th>Value</th><th>Meaning</th></tr>
<tr><td>FA_READ</td><td>Specifies read access to the object. Data can be read from the file.</tr>
<tr><td>FA_WRITE</td><td>Specifies write access to the object. Data can be written to the file. Combine with <tt>FA_READ</tt> for read-write access.</td></tr>
<tr><td>FA_OPEN_EXISTING</td><td>Opens the file. The function fails if the file is not existing. (Default)</td></tr>
<tr><td>FA_OPEN_ALWAYS</td><td>Opens the file if it is existing. If not, a new file will be created.<br>
To append data to the file, use <a href="lseek.html"><tt>f_lseek</tt></a> function after the file open in this method.</td></tr>
<tr><td>FA_CREATE_NEW</td><td>Creates a new file. The function fails with <tt>FR_EXIST</tt> if the file is existing.</td></tr>
<tr><td>FA_CREATE_ALWAYS</td><td>Creates a new file. If the file is existing, it will be truncated and overwritten.</td></tr>
<tr><td>FA_OPEN_ALWAYS</td><td>Opens the file if it is existing. If not, a new file will be created.</td></tr>
<tr><td>FA_OPEN_APPEND</td><td>Same as <tt>FA_OPEN_ALWAYS</tt> except read/write pointer is set end of the file.</td></tr>
</table>
</dd>
</dl>
@@ -74,7 +74,7 @@ To append data to the file, use <a href="lseek.html"><tt>f_lseek</tt></a> functi
<div class="para desc">
<h4>Description</h4>
<p>Before using any file function, a work area (file system object) must be registered to the logical drive with <a href="mount.html"><tt>f_mount</tt></a> function. All API functions except for <a href="fdisk.html"><tt>f_fdisk</tt></a> function can work after this procedure.</p>
<p>Before using any file function, a work area (file system object) must be registered to the logical drive with <a href="mount.html"><tt>f_mount</tt></a> function. All API functions except for <tt>f_mkfs</tt> and <tt>f_fdisk</tt> function can work after this procedure.</p>
<p>After <tt>f_open</tt> function succeeded, the file object is valid. The file object is used for subsequent operations to the file to identify the file. Open file must be closed prior to power down, media removal or re-mount, or the file can be collapsed. To close an open file, use <a href="close.html"><tt>f_close</tt></a> function.</p>
<p>If duplicated file open is needed, read <a href="appnote.html#dup">here</a> carefully. However duplicated open of a file with any write mode flag is always prohibited.</p>
</div>
@@ -82,7 +82,7 @@ To append data to the file, use <a href="lseek.html"><tt>f_lseek</tt></a> functi
<div class="para comp">
<h4>QuickInfo</h4>
<p>Always available. The mode flags, <tt>FA_WRITE, FA_CREATE_ALWAYS, FA_CREATE_NEW and FA_OPEN_ALWAYS</tt>, are not available when <tt>_FS_READONLY == 1</tt>.</p>
<p>Always available. Only <tt>FA_READ</tt> and <tt>FA_OPEN_EXISTING</tt> are supported when <tt>_FS_READONLY == 1</tt>.</p>
</div>
doc/en/rc.html
+4 -3
View File
@@ -82,9 +82,10 @@ Note that if once this error occured at any operation to an open file, the file
<dt id="ma">FR_MKFS_ABORTED</dt>
<dd>The <tt>f_mkfs</tt> function aborted before start in format due to a reason as follows:
<ul>
<li>The disk/partition size is too small.</li>
<li>Not allowable cluster size for this disk. This can occure when number of clusters gets near the boundaries of FAT sub-types.</li>
<li>There is no partition related to the logical drive. (Related option: <tt><a href="config.html#multi_partition">_MULTI_PARTITION</a></tt>)</li>
<li>It is pmpossible to formart with the given parameters.</li>
<li>The size of volume is too small.</li>
<li>The size of given work area is too small.</li>
<li>The partition bound to the logical drive coulud not be found. (Related option: <tt><a href="config.html#multi_partition">_MULTI_PARTITION</a></tt>)</li>
</ul>
</dd>
doc/en/readdir.html
+5 -4
View File
@@ -49,13 +49,13 @@ FRESULT f_readdir (
<div class="para desc">
<h4>Description</h4>
<p>The <tt>f_readdir</tt> function reads a directory item, informations about the object. All items in the directory can be read in sequence by <tt>f_readdir</tt> function calls. Dot entries (<tt>"."</tt> and <tt>".."</tt>) in the sub-directory are filtered out and they will never appear in the read items. When all directory items have been read and no item to read, a nul string is stored into the <tt>fno-&gt;fname[]</tt> without any error. When a null pointer is given to the <tt class="arg">fno</tt>, the read index of the directory object is rewinded.</p>
<p>When support of long file name (LFN) is enabled, a member <tt>altname[]</tt> is defined in the file information structure to store the short file name of the object. In case of any condition listed below, short file name is stored into the <tt>fname[]</tt> and <tt>altname[]</tt> has a null string.</p>
<p>When support of long file name (LFN) is enabled, a member <tt>altname[]</tt> is defined in the file information structure to store the short file name of the object. In case of the some conditions listed below, short file name is stored into the <tt>fname[]</tt> and <tt>altname[]</tt> has a null string.</p>
<ul>
<li>The item has no long file name. (Not the case at exFAT volume)</li>
<li>Setting of <tt>_MAX_LFN</tt> is insufficient for the long file name. (Not the case at <tt>_MAX_LFN == 255</tt>)</li>
<li>The long file name contains any character not allowed in ANSI/OEM code. (Not the case at <tt>_LFN_UNICODE == 1</tt>)</li>
</ul>
<p>There is a problem on reading directory of exFAT volume. The exFAT does not support short file name. This means no name can be returned on the condition avobe. If it is the case, a "?" is returned as file name to indicate that the object is not accessible. To avoid this problem, configure FatFs <tt>_LFN_UNICODE = 1</tt> and <tt>_MAX_LFN = 255</tt> to support the full feature of LFN specification.</p>
<p>There is a problem on reading a directory of exFAT volume. The exFAT does not support short file name. This means no name can be returned on the condition above. If it is the case, a "?" is returned as file name to indicate that the object is not accessible. To avoid this problem, configure FatFs <tt>_LFN_UNICODE = 1</tt> and <tt>_MAX_LFN = 255</tt> to support the full feature of LFN specification.</p>
</div>
@@ -84,7 +84,8 @@ FRESULT scan_files (
res = f_readdir(&amp;dir, &amp;fno); <span class="c">/* Read a directory item */</span>
if (res != FR_OK || fno.fname[0] == 0) break; <span class="c">/* Break on error or end of dir */</span>
if (fno.fattrib &amp; AM_DIR) { <span class="c">/* It is a directory */</span>
sprintf(&amp;path[i = strlen(path)], "/%s", fno.fname);
i = strlen(path);
sprintf(&amp;path[i], "/%s", fno.fname);
res = scan_files(path); <span class="c">/* Enter the directory */</span>
if (res != FR_OK) break;
path[i] = 0;
@@ -106,7 +107,7 @@ int main (void)
char buff[256];
res = f_mount(&fs, "", 1);
res = f_mount(&amp;fs, "", 1);
if (res == FR_OK) {
strcpy(buff, "/");
res = scan_files(buff);
doc/en/stat.html
+1 -1
View File
@@ -54,7 +54,7 @@ FRESULT f_stat (
<div class="para desc">
<h4>Description</h4>
<p>The <tt>f_stat</tt> function checks the existence of a file or sub-directory. If not exist, the function returns with <tt>FR_NO_FILE</tt>. If exist, the function returns with <tt>FR_OK</tt> and the informations of the object, file size, timestamp, attribute and SFN, are stored to the file information structure. For details of the file information, refer to the <tt>FILINFO</tt> structure and <a href="readdir.html"><tt>f_readdir</tt></a> function.</p>
<p>The <tt>f_stat</tt> function checks the existence of a file or sub-directory. If not exist, the function returns with <tt>FR_NO_FILE</tt>. If exist, the function returns with <tt>FR_OK</tt> and the informations of the object, file size, timestamp and attribute, are stored to the file information structure. For details of the file information, refer to the <tt>FILINFO</tt> structure and <a href="readdir.html"><tt>f_readdir</tt></a> function.</p>
</div>
doc/en/truncate.html
+1
View File
@@ -36,6 +36,7 @@ FRESULT f_truncate (
<a href="rc.html#ok">FR_OK</a>,
<a href="rc.html#de">FR_DISK_ERR</a>,
<a href="rc.html#ie">FR_INT_ERR</a>,
<a href="rc.html#dn">FR_DENIED</a>,
<a href="rc.html#io">FR_INVALID_OBJECT</a>,
<a href="rc.html#tm">FR_TIMEOUT</a>
</p>