diff --git a/doc/00index_e.html b/doc/00index_e.html
index 905b7b8..68e22b0 100644
--- a/doc/00index_e.html
+++ b/doc/00index_e.html
@@ -10,11 +10,11 @@
 <link rel="alternate" hreflang="en" title="Original" href="http://elm-chan.org/fsw/ff/00index_e.html">
 <link rel="alternate" hreflang="ja" title="Japanese version" href="00index_j.html">
 <link rel="stylesheet" href="css_e.css" type="text/css" media="screen" title="ELM Default">
-<title>FatFs - Generic FAT File System Module</title>
+<title>FatFs - Generic FAT File System Module (R0.12c)</title>
 </head>
 
 <body>
-<h1>FatFs - Generic FAT File System Module</h1>
+<h1>FatFs - Generic FAT File System Module (R0.12c)</h1>
 <hr>
 
 <div class="abst">
@@ -23,7 +23,7 @@
 
 <h4>Features</h4>
 <ul>
- <li>Windows compatible FAT/exFAT file system.</li>
+ <li>DOS/Windows compatible FAT/exFAT file system.</li>
  <li>Platform independent. Easy to port.</li>
  <li>Very small footprint for program code and work area.</li>
  <li>Various <a href="en/config.html">configuration options</a> to support for:
@@ -44,6 +44,7 @@
 <div class="para">
 <h3>Application Interface</h3>
 <img src="res/layers1.png" class="rset" width="245" height="220" alt="layer">
+<p>FatFs provides various file control functions for the applications as shown below.</p>
 <ul>
  <li>File Access
  <ul>
@@ -103,9 +104,9 @@
 
 
 <div class="para">
-<h3>Device Control Interface</h3>
+<h3>Media Access Interface</h3>
 <img src="res/layers2.png" class="rset" width="245" height="220" alt="layer">
-<p>Since the FatFs module is a file system layer, it is completely separated from the physical devices, such as memory card, harddisk and any type of storage device. FatFs accesses the storage devices via a simple interface shown below. The low level device control module is <em>not a part of FatFs module</em>. It is provided by implementer. Also sample implementations for some platforms are available in the downloads.</p>
+<p>Since the FatFs module is just a file system layer independent of platform and storage device. It is completely separated from the physical devices, such as memory card, harddisk and any type of storage device. The low level device control module is <em>not a part of FatFs module</em> and it needs to be provided by implementer. FatFs accesses the storage devices via a simple media access interface shown below. Also sample implementations for some platforms are available in the downloads.</p>
 <ul>
  <li><a href="en/dstat.html">disk_status</a> - Get device status</li>
  <li><a href="en/dinit.html">disk_initialize</a> - Initialize device</li>
@@ -121,7 +122,7 @@
 <h3>Resources</h3>
 <p>The FatFs module is a free software opened for education, research and development. You can use, modify and/or redistribute it for personal projects or commercial products without any restriction under your responsibility. For further information, refer to the application note.</p>
 <ul>
- <li>Read first: <a href="en/appnote.html">FatFs module application note</a> <span class="mfd">July 10, 2016</span></li>
+ <li>Read first: <a href="en/appnote.html">FatFs module application note</a></li>
  <li>Community: <a href="http://elm-chan.org/fsw/ff/bd/">FatFs User Forum</a></li>
  <li><a href="https://msdn.microsoft.com/en-us/windows/hardware/gg463080.aspx">FAT32 Specification by Microsoft</a>↗ (The authorized document on FAT file system)</li>
  <li><a href="http://elm-chan.org/docs/fat.html">The basics of FAT file system [ja]</a></li>
@@ -136,6 +137,6 @@
 
 
 <hr>
-<p class="foot"><a href="http://elm-chan.org/fsw/ff/00index_e.html">FatFs home page</a></p>
+<p class="foot"><a href="http://elm-chan.org/fsw/ff/00index_e.html">FatFs Homepage</a></p>
 </body>
 </html>
diff --git a/doc/00index_j.html b/doc/00index_j.html
index 51df31d..02c927f 100644
--- a/doc/00index_j.html
+++ b/doc/00index_j.html
@@ -10,11 +10,11 @@
 <link rel="alternate" hreflang="ja" title="オリジナル版" href="http://elm-chan.org/fsw/ff/00index_j.html">
 <link rel="alternate" hreflang="en" title="英文版" href="00index_e.html">
 <link rel="stylesheet" href="css_j.css" type="text/css" media="screen" title="ELM Default">
-<title>FatFs 汎用FATファイルシステム モジュール</title>
+<title>FatFs 汎用FATファイルシステム モジュール (R0.12c)</title>
 </head>
 
 <body>
-<h1>FatFs 汎用FATファイルシステム モジュール</h1>
+<h1>FatFs 汎用FATファイルシステム モジュール (R0.12c)</h1>
 <hr>
 
 <div class="abst">
@@ -22,7 +22,7 @@
 <p>FatFsは小規模な組み込みシステム向けの汎用FAT/exFATファイルシステム モジュールです。ANSI C(C89)準拠でハードウェア アーキテクチャには依存しないので、必要なワーク エリアが確保できれば、8051, PIC, AVR, SH, Z80, 68k, H8, ARMなど安価なマイコンでも使用可能です。このほか、FatFsを極小マイコン向けにシュリンクした<a href="http://elm-chan.org/fsw/ff/00index_p.html">ぷちFatFs</a>もあります。</p>
 <h4>FatFsモジュールの特徴</h4>
 <ul>
- <li>Windows互換 FAT/exFATファイルシステム</li>
+ <li>DOS/Windows互換 FAT/exFATファイルシステム</li>
  <li>プラットフォーム非依存</li>
  <li>コンパクトなコードとRAM使用量</li>
  <li>多くの<a href="ja/config.html">構成オプション</a>:
@@ -41,8 +41,9 @@
 
 
 <div class="para">
-<h3>上位レイヤ インターフェース</h3>
+<h3>アプリケーション インターフェース</h3>
 <img src="res/layers1.png" class="rset" width="245" height="220" alt="layer">
+<p>FatFsモジュールは、上位レイヤに対して次に示すファイルAPIを提供します。</p>
 <ul>
  <li>ファイル アクセス
  <ul>
@@ -102,9 +103,9 @@
 
 
 <div class="para">
-<h3>下位レイヤ インターフェース</h3>
+<h3>デバイス制御インターフェース</h3>
 <img src="res/layers2.png" class="rset" width="245" height="220" alt="layer">
-<p>FatFsモジュールは、単なるファイルシステム レイヤなので、その下位のストレージ デバイス制御レイヤはそれに含まれません。それぞれのプラットフォームやストレージ デバイスに対応した制御レイヤは、インプリメンタによって提供される必要があります。FatFsモジュールは、下位レイヤに対し標準的には次のインターフェースを要求します。一部の拡張機能、たとえばOS関連機能を有効にしたときは、加えてプロセス/メモリ操作関数なども必要になります。サンプル プロジェクトに下位レイヤの実装例を示します。</p>
+<p>FatFsモジュールは、プラットフォームから独立した単なるファイルシステム レイヤです。ストレージ デバイス(例えばメモリ カード)の制御機能はFatFsの構成部分ではないので、インプリメンタによって提供される必要があります。FatFsモジュールは、下位レイヤに対し標準的には次のインターフェースを要求します。一部の拡張機能(たとえばOS関連機能)を利用するときは、これらに加えてプロセス/メモリ操作関数なども必要になります。サンプル プロジェクトに下位レイヤの実装例を示します。</p>
 <ul>
  <li><a href="ja/dstat.html">disk_status</a> - デバイスの状態取得</li>
  <li><a href="ja/dinit.html">disk_initialize</a> - デバイスの初期化</li>
@@ -120,7 +121,7 @@
 <h3>資料</h3>
 <p>FatFsモジュールはフリー ソフトウェアとして教育・研究・開発用に公開しています。どのような利用目的（個人利用から商用まで）でも使用・改変・配布について一切の制限はありませんが、全て利用者の責任の下での利用とします。詳しくはアプリケーション ノートを参照してください。</p>
 <ul>
- <li>最初に読め: <a href="ja/appnote.html">FatFsモジュール アプリケーション ノート</a> <span class="mfd">2016. 9. 4</span></li>
+ <li>最初に読め: <a href="ja/appnote.html">FatFsモジュール アプリケーション ノート</a></li>
  <li>コミュニティ: <a href="http://elm-chan.org/fsw/ff/bd/">FatFsユーザ フォーラム</a></li>
  <li><a href="https://msdn.microsoft.com/en-us/windows/hardware/gg463080.aspx">FATファイルシステム仕様 by Microsoft</a>↗ (The reference document on FAT file system)</li>
  <li><a href="http://elm-chan.org/docs/fat.html">FATファイルシステム概要</a> (↑を読むためのガイド)</li>
diff --git a/doc/css_e.css b/doc/css_e.css
index 99c6714..0813d7b 100644
--- a/doc/css_e.css
+++ b/doc/css_e.css
@@ -14,6 +14,7 @@ strong {}
 pre {border: 1px dashed gray; margin: 0.5em 1em; padding: 0.5em; line-height: 1.2em; font-size: 85%; font-family: "Consolas", "Courier New", monospace; background-color: white;}
 pre span.c {color: green;}
 pre span.k {color: blue;}
+pre span.b {font-weight: bold;}
 pre span.arg {font-style: italic;}
 tt {margin: 0 0.2em; font-size: 0.85em; font-family: "Consolas", "Courier New", monospace; }
 tt.arg {font-style: italic;}
@@ -24,7 +25,7 @@ dl {margin: 0.5em 1em;}
 dd {margin: 0 2em;}
 dt {font-size: 0.85em; font-family: "Consolas", "Courier New", monospace;}
 dl.par dt {margin: 0.5em 0 0 0 ; font-style: italic; }
-dl.ret dt {margin: 0.5em 0 0 0 ; font-size: 0.85em; font-family: "Consolas", "Courier New", monospace;}
+dl.ret dt {margin: 0.5em 0 0 0 ; font-size: 0.85em; font-family: "Consolas", "Courier New", monospace; font-weight: bold; }
 hr {border-width: 1px; margin: 1em;}
 div.abst {font-family: sans-serif;}
 div.para {clear: both; font-family: serif;}
diff --git a/doc/css_j.css b/doc/css_j.css
index 3b1a964..77b634e 100644
--- a/doc/css_j.css
+++ b/doc/css_j.css
@@ -17,6 +17,7 @@ strong {}
 pre {border: 1px dashed gray; margin: 0.5em 1em; padding: 0.5em; line-height: 1.2em; letter-spacing: 0; font-size: 0.85em; font-family: "Consolas", "Courier New", "�l�r �S�V�b�N", monospace; background-color: white;}
 pre span.c {color: green;}
 pre span.k {color: blue;}
+pre span.b {font-weight: bold;}
 pre span.arg {font-style: italic;}
 tt {margin: 0 0.2em; letter-spacing: 0; font-size: 0.85em; font-family: "Consolas", "Courier New", "�l�r �S�V�b�N", monospace;}
 tt.arg {font-style: italic;}
@@ -27,7 +28,7 @@ dl {margin: 0.5em 1em;}
 dd {margin: 0em   2em;}
 dt {font-size: 0.85em; font-family: "Consolas", "Courier New", "�l�r �S�V�b�N", monospace;}
 dl.par dt {margin: 0.5em 0 0 0 ; font-style: italic; letter-spacing: 0;}
-dl.ret dt {margin: 0.5em 0 0 0 ; font-size: 0.85em; font-family: "Consolas", "Courier New", "�l�r �S�V�b�N", monospace; letter-spacing: 0; }
+dl.ret dt {margin: 0.5em 0 0 0 ; font-size: 0.85em; font-family: "Consolas", "Courier New", "�l�r �S�V�b�N", monospace; letter-spacing: 0; font-weight: bold; }
 hr {border-width: 1px; margin: 1em;}
 div.abst {font-family: "�l�r �o�S�V�b�N",sans-serif;}
 div.para {clear: both; font-family: "�l�r �o����",serif;}
diff --git a/doc/en/appnote.html b/doc/en/appnote.html
index 5acfdeb..34d01cf 100644
--- a/doc/en/appnote.html
+++ b/doc/en/appnote.html
@@ -64,7 +64,7 @@ The FatFs module assumes that size of <tt>char</tt>/<tt>short</tt>/<tt>long</tt>
 <div class="para doc" id="limits">
 <h3>Limits</h3>
 <ul>
-<li>File system type: FAT12, FAT16, FAT32(r0.0) and exFAT(r1.0).</li>
+<li>File system type: FAT, FAT32(r0.0) and exFAT(r1.0).</li>
 <li>Number of open files: Unlimited. (depends on available memory)</li>
 <li>Number of volumes: Upto 10.</li>
 <li>Volume size: Upto 2 TiB at 512 bytes/sector.</li>
@@ -144,7 +144,7 @@ And 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 and additional 608 bytes when exFAT enabled.</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 <tt>(_MAX_LFN + 44) / 15 * 32</tt> bytes when exFAT is 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>
@@ -165,22 +165,22 @@ And 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 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/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 because of need for 64-bit integer type.</em></p>
+<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 become one of the standard file systems for removable media as well as FAT. 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 cluster allocation delay, are reduced as well. This feature improves the write throughput to the file.</p>
+<p>Note that the exFAT is a patent of Microsoft Corporation. The exFAT function of FatFs is an implementation based on <cite>US. Pat. App. Pub. No. 2009/0164440 A1</cite>. FatFs module can swich the exFAT on/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>
+<p><em>Remark: Enabling exFAT discards ANSI C (C89) compatibility because of need for 64-bit integer type.</em></p>
+</div>
 
 <div class="para doc" id="reentrant">
 <h3>Re-entrancy</h3>
-<p>The file operations to the different volume is always re-entrant regardless of configurations except when LFN enabled with static working buffer. It can work simultaneously without any mutual exclusion.</p>
-<p>The file operations to the same volume is not re-entrant but it can also be configured thread-safe by option <tt><a href="config.html#fs_reentrant">_FS_REENTRANT</a></tt>. It enables to control exclusive use of each file system object. In this case, also the OS dependent synchronization object control functions, <tt>ff_cre_syncobj/ff_del_syncobj/ff_req_grant/ff_rel_grant</tt>, needed to be added to the project. There are some examples in the <tt>option/syscall.c</tt>.</p>
+<p>The file operations to the <em>different volume</em> each other is always re-entrant regardless of configurations except when LFN enabled with static working buffer. It can work simultaneously without any mutual exclusion.</p>
+<p>The file operations to the <em>same volume</em> is not re-entrant. It can also be configured thread-safe by option <tt><a href="config.html#fs_reentrant">_FS_REENTRANT</a></tt>. It enables to control exclusive use of each file system object. In this case, also the OS dependent synchronization object control functions, <tt>ff_cre_syncobj/ff_del_syncobj/ff_req_grant/ff_rel_grant</tt>, needed to be added to the project. There are some examples in the <tt>option/syscall.c</tt>.</p>
 <p>When a file function is called while the volume is being accessed by other task, the file function to the volume will be suspended until that task leaves the file function. If the wait time exceeded a period defined by <tt>_TIMEOUT</tt>, the file function will abort with <tt>FR_TIMEOUT</tt>. The timeout function might not be supported on the some RTOSs.</p>
-<p>There is an exception on the re-entrancy for <tt>f_mount/f_mkfs/f_fdisk</tt> function. These volume management functions are not re-entrant to the same volume and corresponding physical drive. When use these functions, other tasks need to avoid to access the volume.</p>
-<p>Note that this section describes on the re-entrancy of the FatFs module itself. The <tt>_FS_REENTRANT</tt> controls only exclusive use of each file system object and it does not that prevent to re-enter the low level disk functions. For example, only <tt>disk_status</tt> function can be re-entered at single volume system and any disk function can be re-entered at multiple volume system. Thus the low level disk I/O layer must be always thread-safe when any FatFs API is re-entered by two or more tasks.</p>
+<p>There is an exception on the re-entrancy for <tt>f_mount/f_mkfs/f_fdisk</tt> function. These volume management functions are not re-entrant on the same volume and corresponding physical drive. When use these functions, other tasks need to avoid to access the volume.</p>
+<p>Note that this section describes on the re-entrancy of the FatFs module itself. The <tt>_FS_REENTRANT</tt> controls only exclusive use of each file system object and it does not that prevent re-entering the low level disk functions. For example, only <tt>disk_status</tt> function is re-entered at single volume system and every disk function is re-entered at multiple volume system. Thus the low level disk I/O layer must be always thread-safe when FatFs API is re-entered by two or more tasks.</p>
 </div>
 
 <div class="para doc" id="dup">
-<h3>Duplicated File Access</h3>
+<h3>Duplicated File Open</h3>
 <p>FatFs module does not support the read/write collision control of duplicated open to a file. The duplicated open is permitted only when each of open method to a file is read mode. The duplicated open with one or more write mode to a file is always prohibited, and also open file must not be renamed or deleted. A violation of these rules can cause data colluption.</p>
 <p>The file lock control can be enabled by <tt><a href="config.html#fs_lock">_FS_LOCK</a></tt> option. The value of option defines the number of open objects to manage simultaneously. In this case, if any open, rename or remove that violating the file shareing rule that described above is attempted, the file function will rejected with <tt>FR_LOCKED</tt>. If number of open objects, files and sub-directories, is equal to <tt>_FS_LOCK</tt>, an extra <tt>f_open/f_opendir</tt> function will fail with <tt>FR_TOO_MANY_OPEN_FILES</tt>.</p>
 </div>
@@ -274,7 +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, 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>
+<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 of 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 license that not conflict with FatFs license.</p>
 </div>
 
 <p class="foot"><a href="../00index_e.html">Return Home</a></p>
diff --git a/doc/en/dread.html b/doc/en/dread.html
index b7674a1..b4594c7 100644
--- a/doc/en/dread.html
+++ b/doc/en/dread.html
@@ -60,8 +60,8 @@ DRESULT disk_read (
 <p>The memory address specified by <tt class="arg">buff</tt> is not that always aligned to word boundary because the argument is defined as <tt>BYTE*</tt>. The unaligned read/write request can occure at <a href="appnote.html#fs1">direct transfer</a>. If the bus architecture, especially DMA controller, does not allow unaligned memory access, it should be solved in this function. There are some workarounds described below to avoid this issue.</p>
 <ul>
 <li>Convert word transfer to byte transfer in this function if needed. - Recommended.</li>
-<li>On the <tt>f_read</tt> calls, avoid long read request that includes a whole of sector. - Any direct transfer never occures.</li>
-<li>On the <tt>f_read</tt> calls, make sure that <tt>(((UINT)data &amp; 3) == (f_tell(fp) &amp; 3))</tt> is true. - Word alignment of <tt class="arg">buff</tt> is guaranteed.</li>
+<li>On the <tt>f_read()</tt> calls, avoid long read request that includes a whole of sector. - Any direct transfer never occures.</li>
+<li>On the <tt>f_read(fp, data, btw, bw)</tt> calls, make sure that <tt>(((UINT)data &amp; 3) == (f_tell(fp) &amp; 3))</tt> is true. - Word alignment of <tt class="arg">buff</tt> is guaranteed.</li>
 </ul>
 <p>Generally, a multiple sector transfer request must not be split into single sector transactions to the storage device, or you will not get good read throughput.</p>
 </div>
diff --git a/doc/en/dstat.html b/doc/en/dstat.html
index 78508ba..7092da7 100644
--- a/doc/en/dstat.html
+++ b/doc/en/dstat.html
@@ -35,7 +35,7 @@ DSTATUS disk_status (
 <p>The current drive status is returned in combination of status flags described below. FatFs refers only <tt>STA_NOINIT</tt> and <tt>STA_PROTECT</tt>.</p>
 <dl class="ret">
 <dt>STA_NOINIT</dt>
-<dd>Indicates that the device is not initialized and not ready to work. This flag is set on system reset, media removal or failure of <tt>disk_initialize</tt> function. It is cleared on <tt>disk_initialize</tt> function succeeded. Any media change that occurs asynchronously must be captured and reflect it to the status flags, or auto-mount function will not work correctly. If the system does not support media change detection, application program needs to force de-initialize the file system object and re-mount the volume with <tt>f_mount</tt> function after each media change.</dd>
+<dd>Indicates that the device is not initialized and not ready to work. This flag is set on system reset, media removal or failure of <tt>disk_initialize</tt> function. It is cleared on <tt>disk_initialize</tt> function succeeded. Any media change that occurs asynchronously must be captured and reflect it to the status flags, or auto-mount function will not work correctly. If the system does not support media change detection, application program needs to explicitly re-mount the volume with <tt>f_mount</tt> function after each media change.</dd>
 <dt>STA_NODISK</dt>
 <dd>Indicates that no medium in the drive. This is always cleared at fixed disk drive. Note that FatFs does not refer this flag.</dd>
 <dt>STA_PROTECT</dt>
diff --git a/doc/en/dwrite.html b/doc/en/dwrite.html
index b99eccd..a8c5ce8 100644
--- a/doc/en/dwrite.html
+++ b/doc/en/dwrite.html
@@ -60,7 +60,7 @@ DRESULT disk_write (
 <h4>Description</h4>
 <p>The specified memory address is not that always aligned to word boundary because the type of pointer is defined as <tt>BYTE*</tt>. For more information, refer to the description of <a href="dread.html"><tt>disk_read</tt></a> function.</p>
 <p>Generally, a multiple sector transfer request must not be split into single sector transactions to the storage device, or you will never get good write throughput.</p>
-<p>FatFs expects delayed write function of the disk control layer. The write operation to the media does not need to be completed when return from this function by what write operation is in progress or data is only stored into the write-back cache. But write data on the <tt class="arg">buff</tt> is invalid after return from this function. The write completion request is done by <tt>CTRL_SYNC</tt> command of <tt><a href="dioctl.html">disk_ioctl</a></tt> function. Therefore, if a delayed write function is implemented, the write throughput will be improved.</p>
+<p>FatFs expects delayed write function of the disk control layer. The write operation to the media does not need to be completed when return from this function by what write operation is in progress or data is only stored into the write-back cache. But write data on the <tt class="arg">buff</tt> is invalid after return from this function. The write completion request is done by <tt>CTRL_SYNC</tt> command of <tt><a href="dioctl.html">disk_ioctl</a></tt> function. Therefore, if a delayed write function is implemented, the write throughput of the file system will be improved.</p>
 <p><em>Remarks: Application program MUST NOT call this function, or FAT structure on the volume can be collapsed.</em></p>
 </div>
 
diff --git a/doc/en/expand.html b/doc/en/expand.html
index 54f21d1..8e40d3c 100644
--- a/doc/en/expand.html
+++ b/doc/en/expand.html
@@ -60,8 +60,8 @@ FRESULT f_expand (
 <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 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 changes to the volume 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 FAT access for the contiguous file on the exFAT volume 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 this is not recommended in consideration for future compatibility.</p>
+<p>The contiguous file would have an advantage at time-critical read/write operations. It eliminates some overheads in the file system and the storage media caused by random access due to fragmented file data. Especially FAT access for the contiguous file on the exFAT volume is completely eliminated and storage media will be accessed sequentially.</p>
+<p>Also the contiguous file can be easily accessed directly via low-level disk functions. But this is not recommended in consideration for future compatibility.</p>
 </div>
 
 <div class="para comp">
@@ -79,28 +79,29 @@ FRESULT f_expand (
     res = f_open(fp = malloc(sizeof (FIL)), "file.dat", FA_WRITE|FA_CREATE_ALWAYS);
     if (res) { <span class="c">/* Check if the file has been opened */</span>
         free(fp);
-        ...
+        die("Failed to open the file.");
     }
 
     <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>
-        ...
+        f_close(fp);
         free(fp);
-        ...
+        die("Failed to allocate contiguous area.");
     }
+
     <span class="c">/* Now you have a contiguous file accessible with fp */</span>
 
 </pre>
 <pre>
-    <span class="c">/* Accessing the file data directly via low-level disk functions */</span>
+    <span class="c">/* Accessing the contiguous file via low-level disk functions */</span>
 
     <span class="c">/* Get physical location of the file data */</span>
     drv = fp-&gt;obj.fs-&gt;drv;
-    sect = fp-&gt;obj.fs-&gt;database + fp-&gt;obj.fs-&gt;csize * (fp-&gt;obj.sclust - 2);
+    lba = fp-&gt;obj.fs-&gt;database + fp-&gt;obj.fs-&gt;csize * (fp-&gt;obj.sclust - 2);
 
     <span class="c">/* Write 2048 sectors from top of the file at a time */</span>
-    res = disk_write(drv, buffer, sect, 2048);
+    res = disk_write(drv, buffer, lba, 2048);
 
 </pre>
 </div>
diff --git a/doc/en/fdisk.html b/doc/en/fdisk.html
index 8414f91..e86ec6c 100644
--- a/doc/en/fdisk.html
+++ b/doc/en/fdisk.html
@@ -62,15 +62,14 @@ FRESULT f_fdisk (
     <span class="c">/* Volume management table defined by user (required when _MULTI_PARTITION == 1) */</span>
 
     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>
-        {1, 0}     <span class="c">/* Logical drive 2 ==> 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>
+        {1, 0}     <span class="c">/* "2:" ==> Physical drive 1, auto detection */</span>
     };
 </pre>
 <pre>
     <span class="c">/* Initialize a brand-new disk drive mapped to physical drive 0 */</span>
 
-    FATFS fs;
     DWORD plist[] = {50, 50, 0, 0};  <span class="c">/* Divide drive into two partitions */</span>
     BYTE work[_MAX_SS];
 
diff --git a/doc/en/lseek.html b/doc/en/lseek.html
index cf4f47e..f631979 100644
--- a/doc/en/lseek.html
+++ b/doc/en/lseek.html
@@ -29,7 +29,7 @@ FRESULT f_lseek (
 <dt>fp</dt>
 <dd>Pointer to the open file object.</dd>
 <dt>ofs</dt>
-<dd>Byte offset from top of 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>Byte offset from top of the file to set read/write pointer. 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>
 </dl>
 </div>
 
@@ -48,7 +48,8 @@ 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 <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>
+<p>File read/write ponter in the open file object points the data byte to be read/written at next read/write operation. It advances as the number of bytes read/written. The <tt>f_lseek</tt> function moves the file read/write pointer without any read/write operation to the file.</p>
+<p>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 data area to the file 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>
diff --git a/doc/en/mkfs.html b/doc/en/mkfs.html
index 180ffdf..aba07b9 100644
--- a/doc/en/mkfs.html
+++ b/doc/en/mkfs.html
@@ -29,7 +29,7 @@ FRESULT f_mkfs (
 <h4>Parameters</h4>
 <dl class="par">
 <dt>path</dt>
-<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 may or may not be mounted for the format process.</dd>
+<dd>Pointer to the null-terminated string specifies the <a href="filename.html">logical drive</a> to be formatted. If it has no drive number in it, it means the default drive. The logical drive may or may not be mounted for the format process.</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>
@@ -37,7 +37,7 @@ FRESULT f_mkfs (
 <dt>work</dt>
 <dd>Pointer to the working buffer used 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>
+<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 transactions to the drive and the format process will be finished quickly.</dd>
 </dl>
 </div>
 
@@ -57,9 +57,9 @@ FRESULT f_mkfs (
 <div class="para desc">
 <h4>Description</h4>
 <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>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 size of 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 small 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>When <tt>FM_SFD</tt> is not specified (the volume is bound to a physical drive), 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>
 
diff --git a/doc/en/rc.html b/doc/en/rc.html
index 0e45fbe..89e650d 100644
--- a/doc/en/rc.html
+++ b/doc/en/rc.html
@@ -19,7 +19,7 @@
 <dd>The function succeeded.</dd>
 
 <dt id="de">FR_DISK_ERR</dt>
-<dd>An unrecoverable hard error occured in the lower layer, <tt>disk_read</tt>, <tt>disk_write</tt> or <tt>disk_ioctl</tt> function.<br>Note that if once this error occured at any operation to an open file, the file object is aborted and all operations to the file except for close will be rejected.</dd>
+<dd>The lower layer, <tt>disk_read</tt>, <tt>disk_write</tt> or <tt>disk_ioctl</tt> function, reported that an unrecoverable hard error occured.<br>Note that if once this error occured at any operation to an open file, the file object is aborted and all operations to the file except for close will be rejected.</dd>
 
 <dt id="ie">FR_INT_ERR</dt>
 <dd>Assertion failed. An insanity is detected in the internal process. One of the following possibilities is suspected.
@@ -32,7 +32,14 @@ Note that if once this error occured at any operation to an open file, the file
 </dd>
 
 <dt id="nr">FR_NOT_READY</dt>
-<dd>The storage device cannot work due to a failure of <a href="dinit.html"><tt>disk_initialize</tt></a> function due to no medium or any other reason.</dd>
+<dd>The lower layer, <a href="dinit.html"><tt>disk_initialize</tt></a> function, reported that the storage device could not be got ready to work. One of the following possibilities is suspected.
+<ul>
+<li>No medium in the drive.</li>
+<li>Wrong lower layer implementation for the storage device.</li>
+<li>Wrong hardware configuration.</li>
+<li>The storage device is broken.</li>
+</ul>
+</dd>
 
 <dt id="nf">FR_NO_FILE</dt>
 <dd>Could not find the file.</dd>
diff --git a/doc/en/readdir.html b/doc/en/readdir.html
index 235beee..6d79bd8 100644
--- a/doc/en/readdir.html
+++ b/doc/en/readdir.html
@@ -55,7 +55,7 @@ FRESULT f_readdir (
 <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 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>
+<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, "?" is returned into the <tt>fname[]</tt> 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>
 
 
diff --git a/doc/en/sdir.html b/doc/en/sdir.html
index a01a716..7fff827 100644
--- a/doc/en/sdir.html
+++ b/doc/en/sdir.html
@@ -13,7 +13,7 @@
 
 <div class="para">
 <h2>DIR</h2>
-<p>The <tt>DIR</tt> structure is used for the work area to read a directory by <tt>f_oepndir</tt>, <tt>f_readdir</tt>, <tt>f_findfirst</tt> and <tt>f_findnext</tt> function. Application program must not modify any member in this structure, or any data on the FAT volume can be collapsed.</p>
+<p>The <tt>DIR</tt> structure is used for the work area to read a directory by <tt>f_oepndir</tt>, <tt>f_readdir</tt>, <tt>f_findfirst</tt> and <tt>f_findnext</tt> function. Application program must not modify any member in this structure, or any file on the volume can be collapsed.</p>
 <pre>
 <span class="k">typedef</span> <span class="k">struct</span> {
     _FDID   obj;        <span class="c">/* Owner file sytem object and object identifier */</span>
diff --git a/doc/en/sfileinfo.html b/doc/en/sfileinfo.html
index 6dae1fe..856f739 100644
--- a/doc/en/sfileinfo.html
+++ b/doc/en/sfileinfo.html
@@ -13,7 +13,7 @@
 
 <div class="para">
 <h2>FILINFO</h2>
-<p>The <tt>FILINFO</tt> structure holds information about the object returned by <tt>f_readdir</tt>, <tt>f_findfirst</tt>, <tt>f_findnext</tt> and <tt>f_stat</tt> function.</p>
+<p>The <tt>FILINFO</tt> structure holds information about the object returned by <tt>f_readdir</tt>, <tt>f_findfirst</tt>, <tt>f_findnext</tt> and <tt>f_stat</tt> function. Be careful in the size of structure when LFN is enabled.</p>
 <pre>
 <span class="k">typedef struct</span> {
     FSIZE_t fsize;               <span class="c">/* File size */</span>
diff --git a/doc/ja/appnote.html b/doc/ja/appnote.html
index af93406..d176bd7 100644
--- a/doc/ja/appnote.html
+++ b/doc/ja/appnote.html
@@ -64,7 +64,7 @@ FatFsモジュールはANSI C(C89)準拠で記述されているので、普通
 <div class="para doc" id="limits">
 <h3>限界値</h3>
 <ul>
-<li>ファイルシステム: FAT12, FAT16, FAT32(r0.0) および exFAT(r1.0)。</li>
+<li>ファイルシステム: FAT, FAT32(r0.0) および exFAT(r1.0)。</li>
 <li>同時オープン ファイル数: 無制限。(利用可能メモリによる)</li>
 <li>同時マウント ボリューム数: 最大 10。</li>
 <li>ファイル サイズ: 最大 4GiB - 1 (FATボリューム) および、事実上無制限(exFATボリューム)。</li>
@@ -144,7 +144,7 @@ And any other options are left not changed from default setting.
 <div class="para doc" id="lfn">
 <h3>長いファイル名</h3>
 <p>FatFsモジュールは、長いファイル名(LFN)をサポートします。ファイルに付けられた2つの異なる名前(短いファル名と長いファイル名)は、<tt>f_readdir</tt>関数を除くファイル操作関数において透過です。デフォルト構成では、LFN機能はOFFになっています。LFN機能を有効にするには、<tt><a href="config.html#use_lfn">_USE_LFN</a></tt>を1,2または3に設定し、<tt>option/unicode.c</tt>をプロジェクトに追加します。LFN機能は、加えてある程度のワーク エリア(LFN操作バッファ)を必要とします。バッファ長は使用できるメモリに応じて<tt><a href="config.html#max_lfn">_MAX_LFN</a></tt>で構成されることができます。LFNの長さは最大255文字に達するので、LFN完全対応のためには<tt>_MAX_LFN</tt>は255に設定されるべきです。与えられたファイル名に対してバッファ長が不足した場合、ファイル関数は<tt>FR_INVALID_NAME</tt>で失敗します。</p>
-<p>ファイル関数に再入を行う条件の下でLFN機能を使用する場合は、<tt>_USE_LFN</tt>は2または3に設定されなければなりません。この場合、ファイル関数はワーク エリアを動的に確保(スタックまたはヒープ)します。ワーク エリアのサイズは、<tt>(_MAX_LFN + 1) * 2</tt>バイト(exFAT利用時はさらに+608バイト)になるので、スタック等のサイズはそれを考慮した十分な余裕がなければなりません。</p>
+<p>ファイル関数に再入を行う条件の下でLFN機能を使用する場合は、<tt>_USE_LFN</tt>は2または3に設定されなければなりません。この場合、ファイル関数はワーク エリアを動的に確保(スタックまたはヒープ)します。ワーク エリアのサイズは、<tt>(_MAX_LFN + 1) * 2</tt>バイト(exFAT利用時は加えて<tt>((_MAX_LFN + 44) / 15 * 32</tt>バイト)になるので、これらのメモリ消費量に注意を払う必要があります。</p>
 <table class="lst2 rset">
 <caption>LFN構成 at CM3</caption>
 <tr><th><tt>_CODE_PAGE</tt></th><th>追加コード</th></tr>
@@ -165,10 +165,9 @@ And any other options are left not changed from default setting.
 
 <div class="para doc" id="exfat">
 <h3>exFATファイルシステム</h3>
-<p>exFAT(Microsoft's Extended File Allocation Table)ファイルシステムは、既に組み込みシステムや情報家電で広く使われているFATファイルシステムを置き換える目的で開発されました。exFATは、64GiB以上のSDメモリ カードで標準ファイルシステムに採用されるなど、FATに並びリムーバブル メディアの標準ファイルシステムの一つとなりつつあります。</p>
-<p>exFATボリュームでは、FATボリュームで制約となっていた4GiB以上のサイズのファイルを扱え、ファイルシステムのオーバーヘッド(特にファイル アロケーション ディレイ)も大幅に低減され、書き込みスループットがFATより向上しています。しかし、現リビジョンのFatFsでは、実装上の理由から不連続ファイルへのサイズ拡大を伴う書き込み時のとき、スループットがFATより低下します。<tt>f_expand</tt>関数による連続領域の割り当て機能は、この問題の回避に有効かもしれません。</p>
-<p>exFATはマイクロソフト社が開発したものなので、マイクロソフト社はexFATについていくつかの特許を保有しています。FatFsのexFAT機能は、それの US. Pat. App. Pub. No. 2009/0164440 A1 に基づいた実装です。このため、商用製品でexFAT機能を利用する場合、製品の最終仕向地によってはライセンスが必要になります。最近のFATドライバの多くはexFAT機能を含んでいるため、それらの使用に当たってライセンスが必要になりますが、FatFsは構成オプションでexFAT機能を任意にON/OFFできるため、無効にしてライセンス問題を回避することもできます。</p>
-<p><em>exFATを有効にすると、FatFsモジュールのC89互換は失われます(64ビット整数型が必要なため)。</em></p>
+<p>exFAT(Microsoft's Extended File Allocation Table)ファイルシステムは、既に組み込みシステムや情報家電で広く使われているFATファイルシステムを置き換える目的で開発されました。exFATは、64GiB以上のSDメモリ カードで標準ファイルシステムに採用されるなど、FATに並びリムーバブル メディアの標準ファイルシステムの一つとなっています。exFATボリュームでは、FATボリュームで制約となっていた4GiB以上のサイズのファイルを扱え、ファイルシステムのオーバーヘッド(特にファイル アロケーション ディレイ)も大幅に低減され、書き込みスループットがFATより向上しています。</p>
+<p>exFATはマイクロソフト社が開発したものなので、マイクロソフト社はexFATについていくつかの特許を保有しています。FatFsのexFAT機能は、それの<cite>US. Pat. App. Pub. No. 2009/0164440 A1</cite>に基づいた実装です。このため、商用製品でexFAT機能を利用する場合、製品の最終仕向地によってはライセンスが必要になります。最近のFATドライバの多くはexFAT機能を含んでいるため、それらの使用に当たってライセンスが必要になりますが、FatFsは構成オプションでexFAT機能を任意にON/OFFできるため、無効にしてライセンス問題を回避することもできます。</p>
+<p><em>exFATを有効にすると、FatFsモジュールのANSI C(C89)互換は失われます(64ビット整数型が必要なため)。</em></p>
 </div>
 
 <div class="para doc" id="reentrant">
diff --git a/doc/ja/expand.html b/doc/ja/expand.html
index 27c4e66..8e91cf0 100644
--- a/doc/ja/expand.html
+++ b/doc/ja/expand.html
@@ -30,7 +30,7 @@ FRESULT f_expand (
 <dt>fp</dt>
 <dd>対象となるファイル オブジェクト構造体へのポインタを指定します。</dd>
 <dt>fsz</dt>
-<dd>ファイルに割り当てるバイト単位のサイズ。データ型<tt>FSIZE_t</tt>は、<tt>DWORD</tt>(32-bit)または<tt>QWORD</tt>(64-bit)のエリアスで、exFATサポートの有無により切り替わります。</dd>
+<dd>ファイルに割り当てるバイト単位のサイズ。データ型<tt>FSIZE_t</tt>は、<tt>DWORD</tt>(32ビット)または<tt>QWORD</tt>(64ビット)のエリアスで、exFATサポートの有無により切り替わります。</dd>
 <dt>opt</dt>
 <dd>実際に割り当てを行うかどうか指定するフラグ。</dd>
 </dl>
@@ -79,15 +79,15 @@ FRESULT f_expand (
     res = f_open(fp = malloc(sizeof (FIL)), "file.dat", FA_WRITE|FA_CREATE_ALWAYS);
     if (res) { <span class="c">/* ファイルが開かれたかチェック */</span>
         free(fp);
-        ...
+        die("Failed to open the file.");
     }
 
     <span class="c">/* 100 MiB の連続領域を割り当てる */</span>
     res = f_expand(fp, 104857600, 1);
     if (res) { <span class="c">/* 割り当てられたかチェック */</span>
-        ...
+        f_close(fp);
         free(fp);
-        ...
+        die("Failed to allocate contiguous area.");
     }
     <span class="c">/* 連続ファイル作成成功 fp でアクセス可能 */</span>
 
diff --git a/doc/ja/fdisk.html b/doc/ja/fdisk.html
index 82fc6c2..3e3b084 100644
--- a/doc/ja/fdisk.html
+++ b/doc/ja/fdisk.html
@@ -62,15 +62,14 @@ FRESULT f_fdisk (
     <span class="c">/* ユーザ定義のボリューム管理テーブル (_MULTI_PARTITION == 1 のとき必要) */</span>
 
     PARTITION VolToPart[] = {
-        {0, 1},    <span class="c">/* 論理ドライブ 0 ==> 物理ドライブ 0, 第1区画 */</span>
-        {0, 2},    <span class="c">/* 論理ドライブ 1 ==> 物理ドライブ 0, 第2区画 */</span>
-        {1, 0}     <span class="c">/* 論理ドライブ 2 ==> 物理ドライブ 1, 自動検出 */</span>
+        {0, 1},    <span class="c">/* "0:" ==> 物理ドライブ 0, 第1区画 */</span>
+        {0, 2},    <span class="c">/* "1:" ==> 物理ドライブ 0, 第2区画 */</span>
+        {1, 0}     <span class="c">/* "2:" ==> 物理ドライブ 1, 自動検出 */</span>
     };
 </pre>
 <pre>
     <span class="c">/* 新しい物理ドライブ(0)の初期化 */</span>
 
-    FATFS fs;
     DWORD plist[] = {50, 50, 0, 0};  <span class="c">/* 第1区画,第2区画それぞれに50%ずつ割り当て */</span>
     BYTE work[_MAX_SS];
 
diff --git a/doc/ja/lseek.html b/doc/ja/lseek.html
index 00e4a95..4578187 100644
--- a/doc/ja/lseek.html
+++ b/doc/ja/lseek.html
@@ -28,7 +28,7 @@ FRESULT f_lseek (
 <dt>fp</dt>
 <dd>対象となるファイル オブジェクト構造体へのポインタを指定します。</dd>
 <dt>ofs</dt>
-<dd>移動先のオフセット(リード/ライト ポインタ)値。ファイル先頭からのオフセットをバイト単位で指定します。データ型<tt>FSIZE_t</tt>は、<tt>DWORD</tt>(32-bit)または<tt>QWORD</tt>(64-bit)のエリアスで、exFATサポートの有無により切り替わります。</dd>
+<dd>移動先のオフセット(リード/ライト ポインタ)値。ファイル先頭からのオフセットをバイト単位で指定します。データ型<tt>FSIZE_t</tt>は、<tt>DWORD</tt>(32ビット)または<tt>QWORD</tt>(64ビット)のエリアスで、exFATサポートの有無により切り替わります。</dd>
 </dl>
 </div>
 
@@ -48,7 +48,8 @@ FRESULT f_lseek (
 
 <div class="para desc">
 <h4>解説</h4>
-<p>ファイルのリード/ライト ポインタ(次に読み出し・書き込みされるバイトのオフセット)を移動します。オフセットの原点はファイル先頭です。書き込みモードでファイル サイズより大きな値を指定すると、そこまでファイル サイズが拡張され、拡張された部分のデータは未定義となります。データを遅延無く高速に書き込みたいときは、予めこの関数で必要なサイズまでファイル サイズを拡張しておくと良いでしょう。ファイルに連続したデータ領域を割り当てる必要があるときは、<tt>f_expand</tt>関数を使用してください。<tt>f_lseek</tt>関数が正常終了したあとは、リード/ライト ポインタが正しく移動したかチェックするべきです。リード/ライト ポインタが指定より小さいときは、次の原因が考えられます。</p>
+<p>各ファイル オブジェクトが持つリード/ライト ポインタは、次に読み出し・書き込みされるバイトのオフセットを保持し、読み書きされただけ進みます。この関数は、ファイルへの読み書きを行わずにリード/ライト ポインタのみ移動します。</p>
+<p>書き込みモードでファイル サイズより大きな値を指定すると、そこまでファイル サイズが拡張されますが、拡張された部分のデータは未定義となります。データを遅延無く高速に書き込みたいときは、予めこの関数で必要なサイズまでファイル サイズを拡張しておくと良いでしょう。ファイルに連続したデータ領域を割り当てる必要があるときは、<tt>f_expand</tt>関数を使用してください。<tt>f_lseek</tt>関数が正常終了したあとは、リード/ライト ポインタが正しく移動したかチェックするべきです。リード/ライト ポインタが指定より小さいときは、次の原因が考えられます。</p>
 <ul>
 <li>非書き込みモードまたは高速シーク モードのため、ファイル サイズでクリップされた。</li>
 <li>ファイル拡張中にディスクが満杯になった。</li>
diff --git a/doc/ja/rc.html b/doc/ja/rc.html
index 50005e8..59b4871 100644
--- a/doc/ja/rc.html
+++ b/doc/ja/rc.html
@@ -27,7 +27,14 @@
 </ul>
 ※開かれたファイルの操作においてこのエラーが発生すると、そのファイル オブジェクトはアボート状態となり、クローズ以外の操作ができなくなります。</dd>
 <dt id="nr">FR_NOT_READY</dt>
-<dd>下位レイヤ(<tt>disk_initialize</tt>関数)の失敗。つまり、物理ドライブが動作可能な状態にない。</dd>
+<dd>下位レイヤ(<tt>disk_initialize</tt>関数)の失敗。次のような理由が考えられる。
+<ul>
+<li>ドライブにメディアがセットされていない。</li>
+<li>下位レイヤの実装が不完全。</li>
+<li>間違ったハードウェア構成。</li>
+<li>ストレージ デバイスの故障。</li>
+</ul>
+</dd>
 <dt id="nf">FR_NO_FILE</dt>
 <dd>指定されたファイルが見つからなかった。</dd>
 <dt id="np">FR_NO_PATH</dt>
@@ -51,9 +58,9 @@
 <dt id="io">FR_INVALID_OBJECT</dt>
 <dd>指定されたファイル オブジェクトやディレクトリ オブジェクトが無効、またはヌル ポインタが渡された。無効になる理由は次のことが考えられます。
 <ul>
-<li>オープンされていない、既に閉じられた、破損しているなど。</li>
+<li>オープンされていない、既に閉じられている、破損しているなど。</li>
 <li>そのボリュームでマウント動作があり、ボリューム上の開かれたオブジェクトが全て無効化された。</li>
-<li>物理ドライブがメディアの取り外しで動作不可能になっている。</li>
+<li>物理ドライブがメディアの取り外し等で動作不可能になっている。</li>
 </ul>
 </dd>
 <dt id="wp">FR_WRITE_PROTECTED</dt>
diff --git a/doc/ja/sfileinfo.html b/doc/ja/sfileinfo.html
index f669410..ea06320 100644
--- a/doc/ja/sfileinfo.html
+++ b/doc/ja/sfileinfo.html
@@ -13,7 +13,7 @@
 
 <div class="para">
 <h2>FILINFO</h2>
-<p><tt>FILINFO</tt>構造体は、<tt>f_stat/f_readdir/f_findfirst/f_findnext</tt>関数で返されるオブジェクトに関する情報を保持します。</p>
+<p><tt>FILINFO</tt>構造体は、<tt>f_stat/f_readdir/f_findfirst/f_findnext</tt>関数で返されるオブジェクトに関する情報を保持します。LFN使用時はサイズが大きく増加するので注意が必要です。</p>
 <pre>
 <span class="k">typedef</span> <span class="k">struct</span> {
     FSIZE_t fsize;               <span class="c">/* ファイル サイズ */</span>
diff --git a/doc/res/app4.c b/doc/res/app4.c
index 03d124d..56c07fe 100644
--- a/doc/res/app4.c
+++ b/doc/res/app4.c
@@ -1,5 +1,5 @@
 /*----------------------------------------------------------------------/
-/ Low level disk I/O module function checker
+/ Low level disk I/O module function checker                            /
 /-----------------------------------------------------------------------/
 / WARNING: The data on the target drive will be lost!
 */
@@ -41,8 +41,8 @@ int test_diskio (
 )
 {
     UINT n, cc, ns;
-    DWORD sz_drv, lba, lba2, pns = 1;
-    WORD sz_sect, sz_eblk;
+    DWORD sz_drv, lba, lba2, sz_eblk, pns = 1;
+    WORD sz_sect;
     BYTE *pbuff = (BYTE*)buff;
     DSTATUS ds;
     DRESULT dr;
@@ -113,7 +113,7 @@ int test_diskio (
             printf(" - failed.\n");
         }
         if (dr == RES_OK || sz_eblk >= 2) {
-            printf(" Size of the erase block is %u sectors.\n", sz_eblk);
+            printf(" Size of the erase block is %lu sectors.\n", sz_eblk);
         } else {
             printf(" Size of the erase block is unknown.\n");
         }
@@ -196,7 +196,7 @@ int test_diskio (
         pns++;
 
         /* Single sector write test (misaligned memory address) */
-        printf("**** Single sector write test 2 ****\n");
+        printf("**** Single sector write test (misaligned address) ****\n");
         lba = 5;
         for (n = 0, pn(pns); n < sz_sect; n++) pbuff[n+3] = (BYTE)pn(0);
         printf(" disk_write(%u, 0x%X, %lu, 1)", pdrv, (UINT)(pbuff+3), lba);
diff --git a/doc/res/layers3.png b/doc/res/layers3.png
deleted file mode 100644
index ac439b0..0000000
Binary files a/doc/res/layers3.png and /dev/null differ
diff --git a/doc/res/mkfatimg.zip b/doc/res/mkfatimg.zip
index d0728b4..67d423b 100644
Binary files a/doc/res/mkfatimg.zip and b/doc/res/mkfatimg.zip differ
diff --git a/doc/res/mkfs.xls b/doc/res/mkfs.xls
index f01ddcc..3c615cb 100644
Binary files a/doc/res/mkfs.xls and b/doc/res/mkfs.xls differ
diff --git a/doc/updates.txt b/doc/updates.txt
index ebb6026..d4965f9 100644
--- a/doc/updates.txt
+++ b/doc/updates.txt
@@ -1,5 +1,11 @@
+R0.12c (March 04, 2017)
+  Improved write throughput at the fragmented file on the exFAT volume.
+  Made memory usage for exFAT be able to be reduced as decreasing _MAX_LFN.
+  Fixed successive f_getfree() can return wrong count on the FAT12/16 volume. (appeared at R0.12)
+  Fixed configuration option _VOLUMES cannot be set 10. (appeared at R0.10c)
+
 R0.12b (September 4, 2016)
-  Improved f_rename() to be able to rename objects with the same name but case.
+  Make f_rename() be able to rename objects with the same name but case.
   Fixed an error in the case conversion teble of code page 866. (ff.c)
   Fixed writing data is truncated at the file offset 4GiB on the exFAT volume. (appeared at R0.12)
   Fixed creating a file in the root directory of exFAT volume can fail. (appeared at R0.12)
diff --git a/src/00history.txt b/src/00history.txt
index 49aac28..fa73638 100644
--- a/src/00history.txt
+++ b/src/00history.txt
@@ -212,7 +212,7 @@ R0.10a (January 15, 2014)
 R0.10b (May 19, 2014)
 
   Fixed a hard error in the disk I/O layer can collapse the directory entry.
-  Fixed LFN entry is not deleted on delete/rename an object with lossy converted SFN. (appeared at R0.07)
+  Fixed LFN entry is not deleted when delete/rename an object with lossy converted SFN. (appeared at R0.07)
 
 
 
@@ -268,7 +268,7 @@ R0.12a (July 10, 2016)
 
 R0.12b (September 04, 2016)
 
-  Improved f_rename() to be able to rename objects with the same name but case.
+  Made f_rename() be able to rename objects with the same name but case.
   Fixed an error in the case conversion teble of code page 866. (ff.c)
   Fixed writing data is truncated at the file offset 4GiB on the exFAT volume. (appeared at R0.12)
   Fixed creating a file in the root directory of exFAT volume can fail. (appeared at R0.12)
@@ -277,3 +277,12 @@ R0.12b (September 04, 2016)
   Fixed large file allocation/removing on the exFAT volume collapses allocation bitmap. (appeared at R0.12)
   Fixed some internal errors in f_expand() and f_lseek(). (appeared at R0.12)
 
+
+
+R0.12c (March 04, 2017)
+
+  Improved write throughput at the fragmented file on the exFAT volume.
+  Made memory usage for exFAT be able to be reduced as decreasing _MAX_LFN.
+  Fixed successive f_getfree() can return wrong count on the FAT12/16 volume. (appeared at R0.12)
+  Fixed configuration option _VOLUMES cannot be set 10. (appeared at R0.10c)
+
diff --git a/src/00readme.txt b/src/00readme.txt
index 42426a4..2b7cc76 100644
--- a/src/00readme.txt
+++ b/src/00readme.txt
@@ -1,21 +1,21 @@
-FatFs Module Source Files R0.12a
+FatFs Module Source Files R0.12c
 
 
 FILES
 
-  00readme.txt This file.
-  history.txt  Revision history.
-  ffconf.h     Configuration file for FatFs module.
-  ff.h         Common include file for FatFs and application module.
-  ff.c         FatFs module.
-  diskio.h     Common include file for FatFs and disk I/O module.
-  diskio.c     An example of glue function to attach existing disk I/O module to FatFs.
-  integer.h    Integer type definitions for FatFs.
-  option       Optional external functions.
+  00readme.txt   This file.
+  00history.txt  Revision history.
+  ff.c           FatFs module.
+  ffconf.h       Configuration file of FatFs module.
+  ff.h           Common include file for FatFs and application module.
+  diskio.h       Common include file for FatFs and disk I/O module.
+  diskio.c       An example of glue function to attach existing disk I/O module to FatFs.
+  integer.h      Integer type definitions for FatFs.
+  option         Optional external modules.
 
 
   Low level disk I/O module is not included in this archive because the FatFs
-  module is only a generic file system layer and not depend on any specific
-  storage device. You have to provide a low level disk I/O module that written
-  to control the target storage device.
+  module is only a generic file system layer and it does not depend on any specific
+  storage device. You have to provide a low level disk I/O module written to
+  control the storage device that attached to the target system.
 
diff --git a/src/ff.c b/src/ff.c
index ffc5240..faac347 100644
--- a/src/ff.c
+++ b/src/ff.c
@@ -1,13 +1,13 @@
 /*----------------------------------------------------------------------------/
-/  FatFs - Generic FAT file system module  R0.12b                             /
+/  FatFs - Generic FAT file system module  R0.12c                             /
 /-----------------------------------------------------------------------------/
 /
-/ Copyright (C) 2016, ChaN, all right reserved.
+/ Copyright (C) 2017, 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.
 /
@@ -28,65 +28,11 @@
 
 ---------------------------------------------------------------------------*/
 
-#if _FATFS != 68020	/* Revision ID */
+#if _FATFS != 68300	/* Revision ID */
 #error Wrong include file (ff.h).
 #endif
 
 
-#define	ABORT(fs, res)		{ fp->err = (BYTE)(res); LEAVE_FF(fs, res); }
-
-
-/* Reentrancy related */
-#if _FS_REENTRANT
-#if _USE_LFN == 1
-#error Static LFN work area cannot be used at thread-safe configuration
-#endif
-#define	ENTER_FF(fs)		{ if (!lock_fs(fs)) return FR_TIMEOUT; }
-#define	LEAVE_FF(fs, res)	{ unlock_fs(fs, res); return res; }
-#else
-#define	ENTER_FF(fs)
-#define LEAVE_FF(fs, res)	return res
-#endif
-
-
-
-/* Definitions of sector size */
-#if (_MAX_SS < _MIN_SS) || (_MAX_SS != 512 && _MAX_SS != 1024 && _MAX_SS != 2048 && _MAX_SS != 4096) || (_MIN_SS != 512 && _MIN_SS != 1024 && _MIN_SS != 2048 && _MIN_SS != 4096)
-#error Wrong sector size configuration
-#endif
-#if _MAX_SS == _MIN_SS
-#define	SS(fs)	((UINT)_MAX_SS)	/* Fixed sector size */
-#else
-#define	SS(fs)	((fs)->ssize)	/* Variable sector size */
-#endif
-
-
-/* Timestamp */
-#if _FS_NORTC == 1
-#if _NORTC_YEAR < 1980 || _NORTC_YEAR > 2107 || _NORTC_MON < 1 || _NORTC_MON > 12 || _NORTC_MDAY < 1 || _NORTC_MDAY > 31
-#error Invalid _FS_NORTC settings
-#endif
-#define GET_FATTIME()	((DWORD)(_NORTC_YEAR - 1980) << 25 | (DWORD)_NORTC_MON << 21 | (DWORD)_NORTC_MDAY << 16)
-#else
-#define GET_FATTIME()	get_fattime()
-#endif
-
-
-/* File lock controls */
-#if _FS_LOCK != 0
-#if _FS_READONLY
-#error _FS_LOCK must be 0 at read-only configuration
-#endif
-typedef struct {
-	FATFS *fs;		/* Object ID 1, volume (NULL:blank entry) */
-	DWORD clu;		/* Object ID 2, directory (0:root) */
-	DWORD ofs;		/* Object ID 3, directory offset */
-	WORD ctr;		/* Object open counter, 0:none, 0x01..0xFF:read mode open count, 0x100:write mode */
-} FILESEM;
-#endif
-
-
-
 /* DBCS code ranges and SBCS upper conversion tables */
 
 #if _CODE_PAGE == 932	/* Japanese Shift-JIS */
@@ -351,20 +297,20 @@ typedef struct {
 #endif /* _DF1S */
 
 
-/* File attribute bits (internal use) */
+/* Additional file attribute bits for internal use */
 #define	AM_VOL		0x08	/* Volume label */
 #define AM_LFN		0x0F	/* LFN entry */
 #define AM_MASK		0x3F	/* Mask of defined bits */
 
 
-/* File access control and file status flags (internal use) */
+/* Additional file access control and file status flags for internal use */
 #define FA_SEEKEND	0x20	/* Seek to end of the file on file open */
 #define FA_MODIFIED	0x40	/* File has been modified */
 #define FA_DIRTY	0x80	/* FIL.buf[] needs to be written-back */
 
 
-/* Name status flags */
-#define NSFLAG		11		/* Index of name status byte in fn[] */
+/* Name status flags in fn[] */
+#define NSFLAG		11		/* Index of the name status byte */
 #define NS_LOSS		0x01	/* Out of 8.3 format */
 #define NS_LFN		0x02	/* Force to create LFN entry */
 #define NS_LAST		0x04	/* Last segment */
@@ -375,18 +321,17 @@ typedef struct {
 #define NS_NONAME	0x80	/* Not followed */
 
 
-/* Limits and boundaries (differ from specs but correct for real DOS/Windows) */
-#define MAX_FAT12	0xFF5			/* Maximum number of FAT12 clusters */
-#define	MAX_FAT16	0xFFF5			/* Maximum number of FAT16 clusters */
-#define	MAX_FAT32	0xFFFFFF5		/* Maximum number of FAT32 clusters */
-#define	MAX_EXFAT	0x7FFFFFFD		/* Maximum number of exFAT clusters (limited by implementation) */
-#define MAX_DIR		0x200000		/* Maximum size of FAT directory */
-#define MAX_DIR_EX	0x10000000		/* Maximum size of exFAT directory */
+/* Limits and boundaries */
+#define MAX_DIR		0x200000		/* Max size of FAT directory */
+#define MAX_DIR_EX	0x10000000		/* Max size of exFAT directory */
+#define MAX_FAT12	0xFF5			/* Max FAT12 clusters (differs from specs, but correct for real DOS/Windows behavior) */
+#define	MAX_FAT16	0xFFF5			/* Max FAT16 clusters (differs from specs, but correct for real DOS/Windows behavior) */
+#define	MAX_FAT32	0x0FFFFFF5		/* Max FAT32 clusters (not specified, practical limit) */
+#define	MAX_EXFAT	0x7FFFFFFD		/* Max exFAT clusters (differs from specs, implementation limit) */
 
 
-/* FatFs refers the members in the FAT structures as byte array instead of
-/ structure members because the structure is not binary compatible between
-/ different platforms */
+/* FatFs refers the FAT structure as simple byte array instead of structure member
+/ because the C structure is not binary compatible between different platforms */
 
 #define BS_JmpBoot			0		/* x86 jump instruction (3-byte) */
 #define BS_OEMName			3		/* OEM name (8-byte) */
@@ -432,19 +377,61 @@ typedef struct {
 #define BPB_FatSzEx			84		/* exFAT: FAT size [sector] (DWORD) */
 #define BPB_DataOfsEx		88		/* exFAT: Data offset from top of the volume [sector] (DWORD) */
 #define BPB_NumClusEx		92		/* exFAT: Number of clusters (DWORD) */
-#define BPB_RootClusEx		96		/* exFAT: Root directory cluster (DWORD) */
+#define BPB_RootClusEx		96		/* exFAT: Root directory start cluster (DWORD) */
 #define BPB_VolIDEx			100		/* exFAT: Volume serial number (DWORD) */
 #define BPB_FSVerEx			104		/* exFAT: File system version (WORD) */
 #define BPB_VolFlagEx		106		/* exFAT: Volume flags (BYTE) */
 #define BPB_ActFatEx		107		/* exFAT: Active FAT flags (BYTE) */
-#define BPB_BytsPerSecEx	108		/* exFAT: Log2 of sector size in byte (BYTE) */
-#define BPB_SecPerClusEx	109		/* exFAT: Log2 of cluster size in sector (BYTE) */
+#define BPB_BytsPerSecEx	108		/* exFAT: Log2 of sector size in unit of byte (BYTE) */
+#define BPB_SecPerClusEx	109		/* exFAT: Log2 of cluster size in unit of sector (BYTE) */
 #define BPB_NumFATsEx		110		/* exFAT: Number of FATs (BYTE) */
 #define BPB_DrvNumEx		111		/* exFAT: Physical drive number for int13h (BYTE) */
 #define BPB_PercInUseEx		112		/* exFAT: Percent in use (BYTE) */
 #define	BPB_RsvdEx			113		/* exFAT: Reserved (7-byte) */
 #define BS_BootCodeEx		120		/* exFAT: Boot code (390-byte) */
 
+#define	DIR_Name			0		/* Short file name (11-byte) */
+#define	DIR_Attr			11		/* Attribute (BYTE) */
+#define	DIR_NTres			12		/* Lower case flag (BYTE) */
+#define DIR_CrtTime10		13		/* Created time sub-second (BYTE) */
+#define	DIR_CrtTime			14		/* Created time (DWORD) */
+#define DIR_LstAccDate		18		/* Last accessed date (WORD) */
+#define	DIR_FstClusHI		20		/* Higher 16-bit of first cluster (WORD) */
+#define	DIR_ModTime			22		/* Modified time (DWORD) */
+#define	DIR_FstClusLO		26		/* Lower 16-bit of first cluster (WORD) */
+#define	DIR_FileSize		28		/* File size (DWORD) */
+#define	LDIR_Ord			0		/* LFN: LFN order and LLE flag (BYTE) */
+#define	LDIR_Attr			11		/* LFN: LFN attribute (BYTE) */
+#define	LDIR_Type			12		/* LFN: Entry type (BYTE) */
+#define	LDIR_Chksum			13		/* LFN: Checksum of the SFN (BYTE) */
+#define	LDIR_FstClusLO		26		/* LFN: MBZ field (WORD) */
+#define	XDIR_Type			0		/* exFAT: Type of exFAT directory entry (BYTE) */
+#define	XDIR_NumLabel		1		/* exFAT: Number of volume label characters (BYTE) */
+#define	XDIR_Label			2		/* exFAT: Volume label (11-WORD) */
+#define	XDIR_CaseSum		4		/* exFAT: Sum of case conversion table (DWORD) */
+#define	XDIR_NumSec			1		/* exFAT: Number of secondary entries (BYTE) */
+#define	XDIR_SetSum			2		/* exFAT: Sum of the set of directory entries (WORD) */
+#define	XDIR_Attr			4		/* exFAT: File attribute (WORD) */
+#define	XDIR_CrtTime		8		/* exFAT: Created time (DWORD) */
+#define	XDIR_ModTime		12		/* exFAT: Modified time (DWORD) */
+#define	XDIR_AccTime		16		/* exFAT: Last accessed time (DWORD) */
+#define	XDIR_CrtTime10		20		/* exFAT: Created time subsecond (BYTE) */
+#define	XDIR_ModTime10		21		/* exFAT: Modified time subsecond (BYTE) */
+#define	XDIR_CrtTZ			22		/* exFAT: Created timezone (BYTE) */
+#define	XDIR_ModTZ			23		/* exFAT: Modified timezone (BYTE) */
+#define	XDIR_AccTZ			24		/* exFAT: Last accessed timezone (BYTE) */
+#define	XDIR_GenFlags		33		/* exFAT: General secondary flags (WORD) */
+#define	XDIR_NumName		35		/* exFAT: Number of file name characters (BYTE) */
+#define	XDIR_NameHash		36		/* exFAT: Hash of file name (WORD) */
+#define XDIR_ValidFileSize	40		/* exFAT: Valid file size (QWORD) */
+#define	XDIR_FstClus		52		/* exFAT: First cluster of the file data (DWORD) */
+#define	XDIR_FileSize		56		/* exFAT: File/Directory size (QWORD) */
+
+#define	SZDIRE				32		/* Size of a directory entry */
+#define	DDEM				0xE5	/* Deleted directory entry mark set to DIR_Name[0] */
+#define	RDDEM				0x05	/* Replacement of the character collides with DDEM */
+#define	LLEF				0x40	/* Last long entry flag in LDIR_Ord */
+
 #define	FSI_LeadSig			0		/* FAT32 FSI: Leading signature (DWORD) */
 #define	FSI_StrucSig		484		/* FAT32 FSI: Structure signature (DWORD) */
 #define	FSI_Free_Count		488		/* FAT32 FSI: Number of free clusters (DWORD) */
@@ -463,47 +450,68 @@ typedef struct {
 #define PTE_StLba			8		/* MBR PTE: Start in LBA */
 #define PTE_SizLba			12		/* MBR PTE: Size in LBA */
 
-#define	DIR_Name			0		/* Short file name (11-byte) */
-#define	DIR_Attr			11		/* Attribute (BYTE) */
-#define	DIR_NTres			12		/* Lower case flag (BYTE) */
-#define DIR_CrtTime10		13		/* Created time sub-second (BYTE) */
-#define	DIR_CrtTime			14		/* Created time (DWORD) */
-#define DIR_LstAccDate		18		/* Last accessed date (WORD) */
-#define	DIR_FstClusHI		20		/* Higher 16-bit of first cluster (WORD) */
-#define	DIR_ModTime			22		/* Modified time (DWORD) */
-#define	DIR_FstClusLO		26		/* Lower 16-bit of first cluster (WORD) */
-#define	DIR_FileSize		28		/* File size (DWORD) */
-#define	LDIR_Ord			0		/* LFN entry order and LLE flag (BYTE) */
-#define	LDIR_Attr			11		/* LFN attribute (BYTE) */
-#define	LDIR_Type			12		/* LFN type (BYTE) */
-#define	LDIR_Chksum			13		/* Checksum of the SFN entry (BYTE) */
-#define	LDIR_FstClusLO		26		/* Must be zero (WORD) */
-#define	XDIR_Type			0		/* Type of exFAT directory entry (BYTE) */
-#define	XDIR_NumLabel		1		/* Number of volume label characters (BYTE) */
-#define	XDIR_Label			2		/* Volume label (11-WORD) */
-#define	XDIR_CaseSum		4		/* Sum of case conversion table (DWORD) */
-#define	XDIR_NumSec			1		/* Number of secondary entries (BYTE) */
-#define	XDIR_SetSum			2		/* Sum of the set of directory entries (WORD) */
-#define	XDIR_Attr			4		/* File attribute (WORD) */
-#define	XDIR_CrtTime		8		/* Created time (DWORD) */
-#define	XDIR_ModTime		12		/* Modified time (DWORD) */
-#define	XDIR_AccTime		16		/* Last accessed time (DWORD) */
-#define	XDIR_CrtTime10		20		/* Created time subsecond (BYTE) */
-#define	XDIR_ModTime10		21		/* Modified time subsecond (BYTE) */
-#define	XDIR_CrtTZ			22		/* Created timezone (BYTE) */
-#define	XDIR_ModTZ			23		/* Modified timezone (BYTE) */
-#define	XDIR_AccTZ			24		/* Last accessed timezone (BYTE) */
-#define	XDIR_GenFlags		33		/* Gneral secondary flags (WORD) */
-#define	XDIR_NumName		35		/* Number of file name characters (BYTE) */
-#define	XDIR_NameHash		36		/* Hash of file name (WORD) */
-#define XDIR_ValidFileSize	40		/* Valid file size (QWORD) */
-#define	XDIR_FstClus		52		/* First cluster of the file data (DWORD) */
-#define	XDIR_FileSize		56		/* File/Directory size (QWORD) */
 
-#define	SZDIRE				32		/* Size of a directory entry */
-#define	LLEF				0x40	/* Last long entry flag in LDIR_Ord */
-#define	DDEM				0xE5	/* Deleted directory entry mark set to DIR_Name[0] */
-#define	RDDEM				0x05	/* Replacement of the character collides with DDEM */
+/* Post process after fatal error on file operation */
+#define	ABORT(fs, res)		{ fp->err = (BYTE)(res); LEAVE_FF(fs, res); }
+
+
+/* Reentrancy related */
+#if _FS_REENTRANT
+#if _USE_LFN == 1
+#error Static LFN work area cannot be used at thread-safe configuration
+#endif
+#define	ENTER_FF(fs)		{ if (!lock_fs(fs)) return FR_TIMEOUT; }
+#define	LEAVE_FF(fs, res)	{ unlock_fs(fs, res); return res; }
+#else
+#define	ENTER_FF(fs)
+#define LEAVE_FF(fs, res)	return res
+#endif
+
+
+/* Definitions of volume - partition conversion */
+#if _MULTI_PARTITION
+#define LD2PD(vol) VolToPart[vol].pd	/* Get physical drive number */
+#define LD2PT(vol) VolToPart[vol].pt	/* Get partition index */
+#else
+#define LD2PD(vol) (BYTE)(vol)	/* Each logical drive is bound to the same physical drive number */
+#define LD2PT(vol) 0			/* Find first valid partition or in SFD */
+#endif
+
+
+/* Definitions of sector size */
+#if (_MAX_SS < _MIN_SS) || (_MAX_SS != 512 && _MAX_SS != 1024 && _MAX_SS != 2048 && _MAX_SS != 4096) || (_MIN_SS != 512 && _MIN_SS != 1024 && _MIN_SS != 2048 && _MIN_SS != 4096)
+#error Wrong sector size configuration
+#endif
+#if _MAX_SS == _MIN_SS
+#define	SS(fs)	((UINT)_MAX_SS)	/* Fixed sector size */
+#else
+#define	SS(fs)	((fs)->ssize)	/* Variable sector size */
+#endif
+
+
+/* Timestamp */
+#if _FS_NORTC == 1
+#if _NORTC_YEAR < 1980 || _NORTC_YEAR > 2107 || _NORTC_MON < 1 || _NORTC_MON > 12 || _NORTC_MDAY < 1 || _NORTC_MDAY > 31
+#error Invalid _FS_NORTC settings
+#endif
+#define GET_FATTIME()	((DWORD)(_NORTC_YEAR - 1980) << 25 | (DWORD)_NORTC_MON << 21 | (DWORD)_NORTC_MDAY << 16)
+#else
+#define GET_FATTIME()	get_fattime()
+#endif
+
+
+/* File lock controls */
+#if _FS_LOCK != 0
+#if _FS_READONLY
+#error _FS_LOCK must be 0 at read-only configuration
+#endif
+typedef struct {
+	FATFS *fs;		/* Object ID 1, volume (NULL:blank entry) */
+	DWORD clu;		/* Object ID 2, containing directory (0:root) */
+	DWORD ofs;		/* Object ID 3, offset in the directory */
+	WORD ctr;		/* Object open counter, 0:none, 0x01..0xFF:read mode open count, 0x100:write mode */
+} FILESEM;
+#endif
 
 
 
@@ -515,11 +523,11 @@ typedef struct {
 
 ---------------------------------------------------------------------------*/
 
-/* Remark: Variables here without initial value shall be guaranteed zero/null
-/  at start-up. If not, either the linker or start-up routine being used is
+/* Remark: Variables defined here without initial value shall be guaranteed
+/  zero/null at start-up. If not, the linker option or start-up routine is
 /  not compliance with C standard. */
 
-#if _VOLUMES < 1 || _VOLUMES > 9
+#if _VOLUMES < 1 || _VOLUMES > 10
 #error Wrong _VOLUMES setting
 #endif
 static FATFS *FatFs[_VOLUMES];	/* Pointer to the file system objects (logical drives) */
@@ -533,27 +541,29 @@ static BYTE CurrVol;			/* Current drive */
 static FILESEM Files[_FS_LOCK];	/* Open object lock semaphores */
 #endif
 
-#if _USE_LFN == 0			/* Non-LFN configuration */
+#if _USE_LFN == 0		/* Non-LFN configuration */
 #define	DEF_NAMBUF
 #define INIT_NAMBUF(fs)
 #define	FREE_NAMBUF()
-#else
+
+#else					/* LFN configuration */
 #if _MAX_LFN < 12 || _MAX_LFN > 255
-#error Wrong _MAX_LFN setting
+#error Wrong _MAX_LFN value
 #endif
+#define MAXDIRB(nc)	((nc + 44U) / 15 * SZDIRE)
 
 #if _USE_LFN == 1		/* LFN enabled with static working buffer */
 #if _FS_EXFAT
-static BYTE	DirBuf[SZDIRE*19];	/* Directory entry block scratchpad buffer (19 entries in size) */
+static BYTE	DirBuf[MAXDIRB(_MAX_LFN)];	/* Directory entry block scratchpad buffer */
 #endif
-static WCHAR LfnBuf[_MAX_LFN+1];	/* LFN enabled with static working buffer */
+static WCHAR LfnBuf[_MAX_LFN + 1];	/* LFN enabled with static working buffer */
 #define	DEF_NAMBUF
 #define INIT_NAMBUF(fs)
 #define	FREE_NAMBUF()
 
 #elif _USE_LFN == 2 	/* LFN enabled with dynamic working buffer on the stack */
 #if _FS_EXFAT
-#define	DEF_NAMBUF		WCHAR lbuf[_MAX_LFN+1]; BYTE dbuf[SZDIRE*19];
+#define	DEF_NAMBUF		WCHAR lbuf[_MAX_LFN+1]; BYTE dbuf[MAXDIRB(_MAX_LFN)];
 #define INIT_NAMBUF(fs)	{ (fs)->lfnbuf = lbuf; (fs)->dirbuf = dbuf; }
 #define	FREE_NAMBUF()
 #else
@@ -565,7 +575,7 @@ static WCHAR LfnBuf[_MAX_LFN+1];	/* LFN enabled with static working buffer */
 #elif _USE_LFN == 3 	/* LFN enabled with dynamic working buffer on the heap */
 #if _FS_EXFAT
 #define	DEF_NAMBUF		WCHAR *lfn;
-#define INIT_NAMBUF(fs)	{ lfn = ff_memalloc((_MAX_LFN+1)*2 + SZDIRE*19); if (!lfn) LEAVE_FF(fs, FR_NOT_ENOUGH_CORE); (fs)->lfnbuf = lfn; (fs)->dirbuf = (BYTE*)(lfn+_MAX_LFN+1); }
+#define INIT_NAMBUF(fs)	{ lfn = ff_memalloc((_MAX_LFN+1)*2 + MAXDIRB(_MAX_LFN)); if (!lfn) LEAVE_FF(fs, FR_NOT_ENOUGH_CORE); (fs)->lfnbuf = lfn; (fs)->dirbuf = (BYTE*)(lfn+_MAX_LFN+1); }
 #define	FREE_NAMBUF()	ff_memfree(lfn)
 #else
 #define	DEF_NAMBUF		WCHAR *lfn;
@@ -575,8 +585,9 @@ static WCHAR LfnBuf[_MAX_LFN+1];	/* LFN enabled with static working buffer */
 
 #else
 #error Wrong _USE_LFN setting
+
 #endif
-#endif
+#endif	/* else _USE_LFN == 0 */
 
 #ifdef _EXCVT
 static const BYTE ExCvt[] = _EXCVT;	/* Upper conversion table for SBCS extended characters */
@@ -684,7 +695,9 @@ void mem_cpy (void* dst, const void* src, UINT cnt) {
 	const BYTE *s = (const BYTE*)src;
 
 	if (cnt) {
-		do *d++ = *s++; while (--cnt);
+		do {
+			*d++ = *s++;
+		} while (--cnt);
 	}
 }
 
@@ -693,7 +706,9 @@ static
 void mem_set (void* dst, int val, UINT cnt) {
 	BYTE *d = (BYTE*)dst;
 
-	do *d++ = (BYTE)val; while (--cnt);
+	do {
+		*d++ = (BYTE)val;
+	} while (--cnt);
 }
 
 /* Compare memory block */
@@ -728,7 +743,7 @@ int lock_fs (
 	FATFS* fs		/* File system object */
 )
 {
-	return ff_req_grant(fs->sobj);
+	return (fs && ff_req_grant(fs->sobj)) ? 1 : 0;
 }
 
 
@@ -1030,17 +1045,21 @@ DWORD get_fat (	/* 0xFFFFFFFF:Disk error, 1:Internal error, 2..0x7FFFFFFF:Cluste
 						break;
 					}
 				}
-				if (obj->stat == 3 && cofs < obj->n_cont) {	/* Is it in the contiguous part? */
+				if (obj->stat == 3 && cofs < obj->n_cont) {	/* Is it in the 1st fragment? */
 					val = clst + 1; 	/* Generate the value */
 					break;
 				}
 				if (obj->stat != 2) {	/* Get value from FAT if FAT chain is valid */
-					if (move_window(fs, fs->fatbase + (clst / (SS(fs) / 4))) != FR_OK) break;
-					val = ld_dword(fs->win + clst * 4 % SS(fs)) & 0x7FFFFFFF;
+					if (obj->n_frag != 0) {	/* Is it on the growing edge? */
+						val = 0x7FFFFFFF;	/* Generate EOC */
+					} else {
+						if (move_window(fs, fs->fatbase + (clst / (SS(fs) / 4))) != FR_OK) break;
+						val = ld_dword(fs->win + clst * 4 % SS(fs)) & 0x7FFFFFFF;
+					}
 					break;
 				}
 			}
-			/* go next */
+			/* go to default */
 #endif
 		default:
 			val = 1;	/* Internal error */
@@ -1069,7 +1088,6 @@ FRESULT put_fat (	/* FR_OK(0):succeeded, !=0:error */
 	BYTE *p;
 	FRESULT res = FR_INT_ERR;
 
-
 	if (clst >= 2 && clst < fs->n_fatent) {	/* Check if in valid range */
 		switch (fs->fs_type) {
 		case FS_FAT12 :	/* Bitfield items */
@@ -1120,12 +1138,12 @@ FRESULT put_fat (	/* FR_OK(0):succeeded, !=0:error */
 /* exFAT: Accessing FAT and Allocation Bitmap                            */
 /*-----------------------------------------------------------------------*/
 
-/*---------------------------------------------*/
-/* exFAT: Find a contiguous free cluster block */
-/*---------------------------------------------*/
+/*--------------------------------------*/
+/* Find a contiguous free cluster block */
+/*--------------------------------------*/
 
 static
-DWORD find_bitmap (	/* 0:No free cluster, 2..:Free cluster found, 0xFFFFFFFF:Disk error */
+DWORD find_bitmap (	/* 0:Not found, 2..:Cluster block found, 0xFFFFFFFF:Disk error */
 	FATFS* fs,	/* File system object */
 	DWORD clst,	/* Cluster number to scan from */
 	DWORD ncl	/* Number of contiguous clusters to find (1..) */
@@ -1146,12 +1164,12 @@ DWORD find_bitmap (	/* 0:No free cluster, 2..:Free cluster found, 0xFFFFFFFF:Dis
 			do {
 				bv = fs->win[i] & bm; bm <<= 1;		/* Get bit value */
 				if (++val >= fs->n_fatent - 2) {	/* Next cluster (with wrap-around) */
-					val = 0; bm = 0; i = 4096;
+					val = 0; bm = 0; i = SS(fs);
 				}
 				if (!bv) {	/* Is it a free cluster? */
-					if (++ctr == ncl) return scl + 2;	/* Check run length */
+					if (++ctr == ncl) return scl + 2;	/* Check if run length is sufficient for required */
 				} else {
-					scl = val; ctr = 0;		/* Encountered a live cluster, restart to scan */
+					scl = val; ctr = 0;		/* Encountered a cluster in-use, restart to scan */
 				}
 				if (val == clst) return 0;	/* All cluster scanned? */
 			} while (bm);
@@ -1161,9 +1179,9 @@ DWORD find_bitmap (	/* 0:No free cluster, 2..:Free cluster found, 0xFFFFFFFF:Dis
 }
 
 
-/*------------------------------------*/
-/* exFAT: Set/Clear a block of bitmap */
-/*------------------------------------*/
+/*----------------------------------------*/
+/* Set/Clear a block of allocation bitmap */
+/*----------------------------------------*/
 
 static
 FRESULT change_bitmap (
@@ -1177,7 +1195,6 @@ FRESULT change_bitmap (
 	UINT i;
 	DWORD sect;
 
-
 	clst -= 2;	/* The first bit corresponds to cluster #2 */
 	sect = fs->database + clst / 8 / SS(fs);	/* Sector address (assuming bitmap is located top of the cluster heap) */
 	i = clst / 8 % SS(fs);						/* Byte offset in the sector */
@@ -1199,11 +1216,11 @@ FRESULT change_bitmap (
 
 
 /*---------------------------------------------*/
-/* Complement contiguous part of the FAT chain */
+/* Fill the first fragment of the FAT chain    */
 /*---------------------------------------------*/
 
 static
-FRESULT fill_fat_chain (
+FRESULT fill_first_frag (
 	_FDID* obj	/* Pointer to the corresponding object */
 )
 {
@@ -1220,6 +1237,28 @@ FRESULT fill_fat_chain (
 	return FR_OK;
 }
 
+
+/*---------------------------------------------*/
+/* Fill the last fragment of the FAT chain     */
+/*---------------------------------------------*/
+
+static
+FRESULT fill_last_frag (
+	_FDID* obj,	/* Pointer to the corresponding object */
+	DWORD lcl,	/* Last cluster of the fragment */
+	DWORD term	/* Value to set the last FAT entry */
+)
+{
+	FRESULT res;
+
+	while (obj->n_frag > 0) {	/* Create the last chain on the FAT */
+		res = put_fat(obj->fs, lcl - obj->n_frag + 1, (obj->n_frag > 1) ? lcl - obj->n_frag + 2 : term);
+		if (res != FR_OK) return res;
+		obj->n_frag--;
+	}
+	return FR_OK;
+}
+
 #endif	/* _FS_EXFAT && !_FS_READONLY */
 
 
@@ -1270,7 +1309,7 @@ FRESULT remove_chain (	/* FR_OK(0):succeeded, !=0:error */
 #if _FS_EXFAT || _USE_TRIM
 		if (ecl + 1 == nxt) {	/* Is next cluster contiguous? */
 			ecl = nxt;
-		} else {				/* End of contiguous cluster block */ 
+		} else {				/* End of contiguous cluster block */
 #if _FS_EXFAT
 			if (fs->fs_type == FS_EXFAT) {
 				res = change_bitmap(fs, scl, ecl - scl + 1, 0);	/* Mark the cluster block 'free' on the bitmap */
@@ -1290,10 +1329,10 @@ FRESULT remove_chain (	/* FR_OK(0):succeeded, !=0:error */
 
 #if _FS_EXFAT
 	if (fs->fs_type == FS_EXFAT) {
-		if (pclst == 0) {	/* Does object have no chain? */
+		if (pclst == 0) {	/* Does the object have no chain? */
 			obj->stat = 0;		/* Change the object status 'initial' */
 		} else {
-			if (obj->stat == 3 && pclst >= obj->sclust && pclst <= obj->sclust + obj->n_cont) {	/* Did the chain got contiguous? */
+			if (obj->stat == 3 && pclst >= obj->sclust && pclst <= obj->sclust + obj->n_cont) {	/* Did the chain get contiguous? */
 				obj->stat = 2;	/* Change the object status 'contiguous' */
 			}
 		}
@@ -1325,7 +1364,7 @@ DWORD create_chain (	/* 0:No free cluster, 1:Internal error, 0xFFFFFFFF:Disk err
 	}
 	else {				/* Stretch current chain */
 		cs = get_fat(obj, clst);			/* Check the cluster status */
-		if (cs < 2) return 1;				/* Invalid value */
+		if (cs < 2) return 1;				/* Invalid FAT value */
 		if (cs == 0xFFFFFFFF) return cs;	/* A disk error occurred */
 		if (cs < fs->n_fatent) return cs;	/* It is already followed by next cluster */
 		scl = clst;
@@ -1339,13 +1378,22 @@ DWORD create_chain (	/* 0:No free cluster, 1:Internal error, 0xFFFFFFFF:Disk err
 		if (res == FR_INT_ERR) return 1;
 		if (res == FR_DISK_ERR) return 0xFFFFFFFF;
 		if (clst == 0) {							/* Is it a new chain? */
-			obj->stat = 2;							/* Set status 'contiguous chain' */
-		} else {									/* This is a stretched chain */
+			obj->stat = 2;							/* Set status 'contiguous' */
+		} else {									/* It is a stretched chain */
 			if (obj->stat == 2 && ncl != scl + 1) {	/* Is the chain got fragmented? */
 				obj->n_cont = scl - obj->sclust;	/* Set size of the contiguous part */
 				obj->stat = 3;						/* Change status 'just fragmented' */
 			}
 		}
+		if (obj->stat != 2) {	/* Is the file non-contiguous? */
+			if (ncl == clst + 1) {	/* Is the cluster next to previous one? */
+				obj->n_frag = obj->n_frag ? obj->n_frag + 1 : 2;	/* Increment size of last framgent */
+			} else {				/* New fragment */
+				if (obj->n_frag == 0) obj->n_frag = 1;
+				res = fill_last_frag(obj, clst, ncl);	/* Fill last fragment on the FAT and link it to new one */
+				if (res == FR_OK) obj->n_frag = 1;
+			}
+		}
 	} else
 #endif
 	{	/* On the FAT12/16/32 volume */
@@ -1361,23 +1409,18 @@ DWORD create_chain (	/* 0:No free cluster, 1:Internal error, 0xFFFFFFFF:Disk err
 			if (cs == 1 || cs == 0xFFFFFFFF) return cs;	/* An error occurred */
 			if (ncl == scl) return 0;		/* No free cluster */
 		}
-	}
-
-	if (_FS_EXFAT && fs->fs_type == FS_EXFAT && obj->stat == 2) {	/* Is it a contiguous chain? */
-		res = FR_OK;						/* FAT does not need to be written */
-	} else {
 		res = put_fat(fs, ncl, 0xFFFFFFFF);	/* Mark the new cluster 'EOC' */
-		if (res == FR_OK && clst) {
+		if (res == FR_OK && clst != 0) {
 			res = put_fat(fs, clst, ncl);	/* Link it from the previous one if needed */
 		}
 	}
 
 	if (res == FR_OK) {			/* Update FSINFO if function succeeded. */
 		fs->last_clst = ncl;
-		if (fs->free_clst < fs->n_fatent - 2) fs->free_clst--;
+		if (fs->free_clst <= fs->n_fatent - 2) fs->free_clst--;
 		fs->fsi_flag |= 1;
 	} else {
-		ncl = (res == FR_DISK_ERR) ? 0xFFFFFFFF : 1;	/* Failed. Create error status */
+		ncl = (res == FR_DISK_ERR) ? 0xFFFFFFFF : 1;	/* Failed. Generate error status */
 	}
 
 	return ncl;		/* Return new cluster number or error status */
@@ -1519,7 +1562,7 @@ FRESULT dir_next (	/* FR_OK(0):succeeded, FR_NO_FILE:End of table, FR_DENIED:Cou
 					}
 					fs->winsect -= n;							/* Restore window offset */
 #else
-					if (!stretch) dp->sect = 0;					/* If no stretch, report EOT (this is to suppress warning) */
+					if (!stretch) dp->sect = 0;					/* (this line is to suppress compiler warning) */
 					dp->sect = 0; return FR_NO_FILE;			/* Report EOT */
 #endif
 				}
@@ -1676,9 +1719,9 @@ int pick_lfn (			/* 1:succeeded, 0:buffer overflow or invalid LFN entry */
 	WCHAR wc, uc;
 
 
-	if (ld_word(dir + LDIR_FstClusLO) != 0) return 0;	/* Check LDIR_FstClusLO */
+	if (ld_word(dir + LDIR_FstClusLO) != 0) return 0;	/* Check LDIR_FstClusLO is 0 */
 
-	i = ((dir[LDIR_Ord] & 0x3F) - 1) * 13;	/* Offset in the LFN buffer */
+	i = ((dir[LDIR_Ord] & ~LLEF) - 1) * 13;	/* Offset in the LFN buffer */
 
 	for (wc = 1, s = 0; s < 13; s++) {		/* Process all characters in the entry */
 		uc = ld_word(dir + LfnOfs[s]);		/* Pick an LFN character */
@@ -1809,7 +1852,9 @@ BYTE sum_sfn (
 	BYTE sum = 0;
 	UINT n = 11;
 
-	do sum = (sum >> 1) + (sum << 7) + *dir++; while (--n);
+	do {
+		sum = (sum >> 1) + (sum << 7) + *dir++;
+	} while (--n);
 	return sum;
 }
 
@@ -1893,30 +1938,26 @@ void get_xdir_info (
 #endif
 
 	/* Get file name */
+	di = 0;
 #if _LFN_UNICODE
-	if (dirb[XDIR_NumName] <= _MAX_LFN) {
-		for (si = SZDIRE * 2, di = 0; di < dirb[XDIR_NumName]; si += 2, di++) {
-			if ((si % SZDIRE) == 0) si += 2;	/* Skip entry type field */
-			w = ld_word(dirb + si);				/* Get a character */
-			fno->fname[di] = w;					/* Store it */
-		}
-	} else {
-		di = 0;	/* Buffer overflow and inaccessible object */
+	for (si = SZDIRE * 2; di < dirb[XDIR_NumName]; si += 2, di++) {
+		if ((si % SZDIRE) == 0) si += 2;		/* Skip entry type field */
+		w = ld_word(dirb + si);					/* Get a character */
+		if (di >= _MAX_LFN) { di = 0; break; }	/* Buffer overflow --> inaccessible object name */
+		fno->fname[di] = w;						/* Store it */
 	}
 #else
-	for (si = SZDIRE * 2, di = nc = 0; nc < dirb[XDIR_NumName]; si += 2, nc++) {
-		if ((si % SZDIRE) == 0) si += 2;	/* Skip entry type field */
-		w = ld_word(dirb + si);				/* Get a character */
-		w = ff_convert(w, 0);				/* Unicode -> OEM */
-		if (w == 0) { di = 0; break; }		/* Could not be converted and inaccessible object */
-		if (_DF1S && w >= 0x100) {			/* Put 1st byte if it is a DBC (always false at SBCS cfg) */
-			fno->fname[di++] = (char)(w >> 8);
+	for (si = SZDIRE * 2, nc = 0; nc < dirb[XDIR_NumName]; si += 2, nc++) {
+		if ((si % SZDIRE) == 0) si += 2;		/* Skip entry type field */
+		w = ff_convert(ld_word(dirb + si), 0);	/* Get a character and Unicode -> OEM */
+		if (_DF1S && w >= 0x100) {				/* Is it a double byte char? (always false at SBCS cfg) */
+			fno->fname[di++] = (char)(w >> 8);	/* Put 1st byte of the DBC */
 		}
-		if (di >= _MAX_LFN) { di = 0; break; }	/* Buffer overflow and inaccessible object */
+		if (w == 0 || di >= _MAX_LFN) { di = 0; break; }	/* Invalid char or buffer overflow --> inaccessible object name */
 		fno->fname[di++] = (char)w;
 	}
 #endif
-	if (di == 0) fno->fname[di++] = '?';	/* Inaccessible object? */
+	if (di == 0) fno->fname[di++] = '?';	/* Inaccessible object name? */
 	fno->fname[di] = 0;						/* Terminate file name */
 
 	fno->altname[0] = 0;							/* No SFN */
@@ -1939,7 +1980,7 @@ FRESULT load_xdir (	/* FR_INT_ERR: invalid entry block */
 )
 {
 	FRESULT res;
-	UINT i, nent;
+	UINT i, sz_ent;
 	BYTE* dirb = dp->obj.fs->dirbuf;	/* Pointer to the on-memory direcotry entry block 85+C0+C1s */
 
 
@@ -1947,8 +1988,9 @@ FRESULT load_xdir (	/* FR_INT_ERR: invalid entry block */
 	res = move_window(dp->obj.fs, dp->sect);
 	if (res != FR_OK) return res;
 	if (dp->dir[XDIR_Type] != 0x85) return FR_INT_ERR;
-	mem_cpy(dirb, dp->dir, SZDIRE);
-	nent = dirb[XDIR_NumSec] + 1;
+	mem_cpy(dirb + 0, dp->dir, SZDIRE);
+	sz_ent = (dirb[XDIR_NumSec] + 1) * SZDIRE;
+	if (sz_ent < 3 * SZDIRE || sz_ent > 19 * SZDIRE) return FR_INT_ERR;
 
 	/* Load C0 entry */
 	res = dir_next(dp, 0);
@@ -1957,40 +1999,39 @@ FRESULT load_xdir (	/* FR_INT_ERR: invalid entry block */
 	if (res != FR_OK) return res;
 	if (dp->dir[XDIR_Type] != 0xC0) return FR_INT_ERR;
 	mem_cpy(dirb + SZDIRE, dp->dir, SZDIRE);
+	if (MAXDIRB(dirb[XDIR_NumName]) > sz_ent) return FR_INT_ERR;
 
 	/* Load C1 entries */
-	if (nent < 3 || nent > 19) return FR_NO_FILE;
-	i = SZDIRE * 2; nent *= SZDIRE;
+	i = SZDIRE * 2;	/* C1 offset */
 	do {
 		res = dir_next(dp, 0);
 		if (res != FR_OK) return res;
 		res = move_window(dp->obj.fs, dp->sect);
 		if (res != FR_OK) return res;
 		if (dp->dir[XDIR_Type] != 0xC1) return FR_INT_ERR;
-		mem_cpy(dirb + i, dp->dir, SZDIRE);
-		i += SZDIRE;
-	} while (i < nent);
-
-	/* Sanity check */
-	if (xdir_sum(dirb) != ld_word(dirb + XDIR_SetSum)) return FR_INT_ERR;
+		if (i < MAXDIRB(_MAX_LFN)) mem_cpy(dirb + i, dp->dir, SZDIRE);
+	} while ((i += SZDIRE) < sz_ent);
 
+	/* Sanity check (do it when accessible object name) */
+	if (i <= MAXDIRB(_MAX_LFN)) {
+		if (xdir_sum(dirb) != ld_word(dirb + XDIR_SetSum)) return FR_INT_ERR;
+	}
 	return FR_OK;
 }
 
 
-#if !_FS_READONLY || _FS_RPATH != 0 
+#if !_FS_READONLY || _FS_RPATH != 0
 /*------------------------------------------------*/
 /* exFAT: Load the object's directory entry block */
 /*------------------------------------------------*/
 static
 FRESULT load_obj_dir (	
 	DIR* dp,			/* Blank directory object to be used to access containing direcotry */
-	const _FDID* obj	/* Object with containing directory information */
+	const _FDID* obj	/* Object with its containing directory information */
 )
 {
 	FRESULT res;
 
-
 	/* Open object containing directory */
 	dp->obj.fs = obj->fs;
 	dp->obj.sclust = obj->c_scl;
@@ -1998,7 +2039,7 @@ FRESULT load_obj_dir (
 	dp->obj.objsize = obj->c_size & 0xFFFFFF00;
 	dp->blk_ofs = obj->c_ofs;
 
-	res = dir_sdi(dp, dp->blk_ofs);	/* Goto the block location */
+	res = dir_sdi(dp, dp->blk_ofs);	/* Goto object's entry block */
 	if (res == FR_OK) {
 		res = load_xdir(dp);		/* Load the object's entry block */
 	}
@@ -2055,24 +2096,25 @@ void create_xdir (
 	WCHAR chr;
 
 
-	mem_set(dirb, 0, 2 * SZDIRE);			/* Initialize 85+C0 entry */
+	/* Create 85+C0 entry */
+	mem_set(dirb, 0, 2 * SZDIRE);
 	dirb[XDIR_Type] = 0x85;
 	dirb[XDIR_Type + SZDIRE] = 0xC0;
-	st_word(dirb + XDIR_NameHash, xname_sum(lfn));	/* Set name hash */
 
-	i = SZDIRE * 2;	/* C1 offset */
-	nc = 0; nb = 1; chr = 1;
+	/* Create C1 entries */
+	nc = 0; nb = 1; chr = 1; i = SZDIRE * 2;
 	do {
 		dirb[i++] = 0xC1; dirb[i++] = 0;	/* Entry type C1 */
 		do {	/* Fill name field */
 			if (chr && (chr = lfn[nc]) != 0) nc++;	/* Get a character if exist */
-			st_word(dirb + i, chr); i += 2;	/* Store it */
-		} while (i % SZDIRE);
+			st_word(dirb + i, chr); 		/* Store it */
+		} while ((i += 2) % SZDIRE != 0);
 		nb++;
 	} while (lfn[nc]);	/* Fill next entry if any char follows */
 
 	dirb[XDIR_NumName] = nc;	/* Set name length */
-	dirb[XDIR_NumSec] = nb;		/* Set number of C0+C1s */
+	dirb[XDIR_NumSec] = nb;		/* Set block length */
+	st_word(dirb + XDIR_NameHash, xname_sum(lfn));	/* Set name hash */
 }
 
 #endif	/* !_FS_READONLY */
@@ -2102,7 +2144,9 @@ FRESULT dir_read (
 		res = move_window(fs, dp->sect);
 		if (res != FR_OK) break;
 		c = dp->dir[DIR_Name];	/* Test for the entry type */
-		if (c == 0) { res = FR_NO_FILE; break; }	/* Reached to end of the directory */
+		if (c == 0) {
+			res = FR_NO_FILE; break; /* Reached to end of the directory */
+		}
 #if _FS_EXFAT
 		if (fs->fs_type == FS_EXFAT) {	/* On the exFAT volume */
 			if (_USE_LABEL && vol) {
@@ -2183,7 +2227,10 @@ FRESULT dir_find (	/* FR_OK(0):succeeded, !=0:error */
 		WORD hash = xname_sum(fs->lfnbuf);		/* Hash value of the name to find */
 
 		while ((res = dir_read(dp, 0)) == FR_OK) {	/* Read an item */
-			if (ld_word(fs->dirbuf + XDIR_NameHash) != hash) continue;	/* Skip the comparison if hash value mismatched */
+#if _MAX_LFN < 255
+			if (fs->dirbuf[XDIR_NumName] > _MAX_LFN) continue;			/* Skip comparison if inaccessible object name */
+#endif
+			if (ld_word(fs->dirbuf + XDIR_NameHash) != hash) continue;	/* Skip comparison if hash mismatched */
 			for (nc = fs->dirbuf[XDIR_NumName], di = SZDIRE * 2, ni = 0; nc; nc--, di += 2, ni++) {	/* Compare the name */
 				if ((di % SZDIRE) == 0) di += 2;
 				if (ff_wtoupper(ld_word(fs->dirbuf + di)) != ff_wtoupper(fs->lfnbuf[ni])) break;
@@ -2263,19 +2310,20 @@ FRESULT dir_register (	/* FR_OK:succeeded, FR_DENIED:no free entry or too many S
 		nent = (nlen + 14) / 15 + 2;	/* Number of entries to allocate (85+C0+C1s) */
 		res = dir_alloc(dp, nent);		/* Allocate entries */
 		if (res != FR_OK) return res;
-		dp->blk_ofs = dp->dptr - SZDIRE * (nent - 1);			/* Set block position */
+		dp->blk_ofs = dp->dptr - SZDIRE * (nent - 1);	/* Set the allocated entry block offset */
 
 		if (dp->obj.sclust != 0 && (dp->obj.stat & 4)) {	/* Has the sub-directory been stretched? */
-			dp->obj.stat &= 3;
-			dp->obj.objsize += (DWORD)fs->csize * SS(fs);	/* Increase object size by cluster size */
-			res = fill_fat_chain(&dp->obj);	/* Complement FAT chain if needed */
+			dp->obj.objsize += (DWORD)fs->csize * SS(fs);	/* Increase the directory size by cluster size */
+			res = fill_first_frag(&dp->obj);				/* Fill first fragment on the FAT if needed */
+			if (res != FR_OK) return res;
+			res = fill_last_frag(&dp->obj, dp->clust, 0xFFFFFFFF);	/* Fill last fragment on the FAT if needed */
+			if (res != FR_OK) return res;
+			res = load_obj_dir(&dj, &dp->obj);				/* Load the object status */
 			if (res != FR_OK) return res;
-			res = load_obj_dir(&dj, &dp->obj);
-			if (res != FR_OK) return res;	/* Load the object status */
 			st_qword(fs->dirbuf + XDIR_FileSize, dp->obj.objsize);		/* Update the allocation status */
 			st_qword(fs->dirbuf + XDIR_ValidFileSize, dp->obj.objsize);
 			fs->dirbuf[XDIR_GenFlags] = dp->obj.stat | 1;
-			res = store_xdir(&dj);			/* Store the object status */
+			res = store_xdir(&dj);							/* Store the object status */
 			if (res != FR_OK) return res;
 		}
 
@@ -2454,7 +2502,7 @@ void get_fileinfo (		/* No return code */
 #endif
 		fno->altname[j] = c;
 		if (!lfv) {
-			if (IsUpper(c) && (dp->dir[DIR_NTres] & (i >= 9 ? NS_EXT : NS_BODY))) {
+			if (IsUpper(c) && (dp->dir[DIR_NTres] & ((i >= 9) ? NS_EXT : NS_BODY))) {
 				c += 0x20;			/* To lower */
 			}
 			fno->fname[j] = c;
@@ -2775,14 +2823,16 @@ FRESULT follow_path (	/* FR_OK(0): successful, !=0: error code */
 
 #if _FS_RPATH != 0
 	if (*path != '/' && *path != '\\') {	/* Without heading separator */
-		obj->sclust = fs->cdir;				/* Start from the current directory */
+		obj->sclust = fs->cdir;				/* Start from current directory */
 	} else
 #endif
 	{										/* With heading separator */
 		while (*path == '/' || *path == '\\') path++;	/* Strip heading separator */
-		obj->sclust = 0;					/* Start from the root directory */
+		obj->sclust = 0;					/* Start from root directory */
 	}
-#if _FS_EXFAT && _FS_RPATH != 0
+#if _FS_EXFAT
+	obj->n_frag = 0;	/* Invalidate last fragment counter of the object */
+#if _FS_RPATH != 0
 	if (fs->fs_type == FS_EXFAT && obj->sclust) {	/* Retrieve the sub-directory status if needed */
 		DIR dj;
 
@@ -2794,6 +2844,7 @@ FRESULT follow_path (	/* FR_OK(0): successful, !=0: error code */
 		obj->objsize = ld_dword(fs->dirbuf + XDIR_FileSize);
 		obj->stat = fs->dirbuf[XDIR_GenFlags] & 2;
 	}
+#endif
 #endif
 
 	if ((UINT)*path < ' ') {				/* Null path name is the origin directory itself */
@@ -2824,8 +2875,8 @@ FRESULT follow_path (	/* FR_OK(0): successful, !=0: error code */
 				res = FR_NO_PATH; break;
 			}
 #if _FS_EXFAT
-			if (fs->fs_type == FS_EXFAT) {
-				obj->c_scl = obj->sclust;		/* Save containing directory information for next dir */
+			if (fs->fs_type == FS_EXFAT) {		/* Save containing directory information for next dir */
+				obj->c_scl = obj->sclust;
 				obj->c_size = ((DWORD)obj->objsize & 0xFFFFFF00) | obj->stat;
 				obj->c_ofs = dp->blk_ofs;
 				obj->sclust = ld_dword(fs->dirbuf + XDIR_FstClus);	/* Open next directory */
@@ -2858,7 +2909,7 @@ int get_ldnumber (		/* Returns logical drive number (-1:invalid drive) */
 	UINT i;
 	int vol = -1;
 #if _STR_VOLUME_ID		/* Find string drive id */
-	static const char* const str[] = {_VOLUME_STRS};
+	static const char* const volid[] = {_VOLUME_STRS};
 	const char *sp;
 	char c;
 	TCHAR tc;
@@ -2869,7 +2920,7 @@ int get_ldnumber (		/* Returns logical drive number (-1:invalid drive) */
 		for (tt = *path; (UINT)*tt >= (_USE_LFN ? ' ' : '!') && *tt != ':'; tt++) ;	/* Find ':' in the path */
 		if (*tt == ':') {	/* If a ':' is exist in the path name */
 			tp = *path;
-			i = *tp++ - '0'; 
+			i = *tp++ - '0';
 			if (i < 10 && tp == tt) {	/* Is there a numeric drive id? */
 				if (i < _VOLUMES) {	/* If a drive id is found, get the value and strip it */
 					vol = (int)i;
@@ -2880,7 +2931,7 @@ int get_ldnumber (		/* Returns logical drive number (-1:invalid drive) */
 			 else {	/* No numeric drive number, find string drive id */
 				i = 0; tt++;
 				do {
-					sp = str[i]; tp = *path;
+					sp = volid[i]; tp = *path;
 					do {	/* Compare a string drive id with path name */
 						c = *sp++; tc = *tp++;
 						if (IsLower(tc)) tc -= 0x20;
@@ -2913,13 +2964,13 @@ int get_ldnumber (		/* Returns logical drive number (-1:invalid drive) */
 static
 BYTE check_fs (	/* 0:FAT, 1:exFAT, 2:Valid BS but not FAT, 3:Not a BS, 4:Disk error */
 	FATFS* fs,	/* File system object */
-	DWORD sect	/* Sector# (lba) to check if it is an FAT-VBR or not */
+	DWORD sect	/* Sector# (lba) to load and check if it is an FAT-VBR or not */
 )
 {
 	fs->wflag = 0; fs->winsect = 0xFFFFFFFF;		/* Invaidate window */
 	if (move_window(fs, sect) != FR_OK) return 4;	/* Load boot record */
 
-	if (ld_word(fs->win + BS_55AA) != 0xAA55) return 3;	/* Check boot record signature (always placed at offset 510 even if the sector size is >512) */
+	if (ld_word(fs->win + BS_55AA) != 0xAA55) return 3;	/* Check boot record signature (always placed here even if the sector size is >512) */
 
 	if (fs->win[BS_JmpBoot] == 0xE9 || (fs->win[BS_JmpBoot] == 0xEB && fs->win[BS_JmpBoot + 2] == 0x90)) {
 		if ((ld_dword(fs->win + BS_FilSysType) & 0xFFFFFF) == 0x544146) return 0;	/* Check "FAT" string */
@@ -2989,29 +3040,30 @@ FRESULT find_volume (	/* FR_OK(0): successful, !=0: any error occurred */
 	if (!_FS_READONLY && mode && (stat & STA_PROTECT)) { /* Check disk write protection if needed */
 		return FR_WRITE_PROTECTED;
 	}
-#if _MAX_SS != _MIN_SS						/* Get sector size (multiple sector size cfg only) */
+#if _MAX_SS != _MIN_SS					/* Get sector size (multiple sector size cfg only) */
 	if (disk_ioctl(fs->drv, GET_SECTOR_SIZE, &SS(fs)) != RES_OK) return FR_DISK_ERR;
 	if (SS(fs) > _MAX_SS || SS(fs) < _MIN_SS || (SS(fs) & (SS(fs) - 1))) return FR_DISK_ERR;
 #endif
-	/* Find an FAT partition on the drive. Supports only generic partitioning, FDISK and SFD. */
+
+	/* Find an FAT partition on the drive. Supports only generic partitioning rules, FDISK and SFD. */
 	bsect = 0;
 	fmt = check_fs(fs, bsect);			/* Load sector 0 and check if it is an FAT-VBR as SFD */
 	if (fmt == 2 || (fmt < 2 && LD2PT(vol) != 0)) {	/* Not an FAT-VBR or forced partition number */
-		for (i = 0; i < 4; i++) {			/* Get partition offset */
+		for (i = 0; i < 4; i++) {		/* Get partition offset */
 			pt = fs->win + (MBR_Table + i * SZ_PTE);
 			br[i] = pt[PTE_System] ? ld_dword(pt + PTE_StLba) : 0;
 		}
-		i = LD2PT(vol);						/* Partition number: 0:auto, 1-4:forced */
+		i = LD2PT(vol);					/* Partition number: 0:auto, 1-4:forced */
 		if (i) i--;
-		do {								/* Find an FAT volume */
+		do {							/* Find an FAT volume */
 			bsect = br[i];
 			fmt = bsect ? check_fs(fs, bsect) : 3;	/* Check the partition */
-		} while (!LD2PT(vol) && fmt >= 2 && ++i < 4);
+		} while (LD2PT(vol) == 0 && fmt >= 2 && ++i < 4);
 	}
 	if (fmt == 4) return FR_DISK_ERR;		/* An error occured in the disk I/O layer */
 	if (fmt >= 2) return FR_NO_FILESYSTEM;	/* No FAT volume is found */
 
-	/* An FAT volume is found. Following code initializes the file system object */
+	/* An FAT volume is found (bsect). Following code initializes the file system object */
 
 #if _FS_EXFAT
 	if (fmt == 1) {
@@ -3022,8 +3074,9 @@ FRESULT find_volume (	/* FR_OK(0): successful, !=0: any error occurred */
 
 		if (ld_word(fs->win + BPB_FSVerEx) != 0x100) return FR_NO_FILESYSTEM;	/* Check exFAT revision (Must be 1.0) */
 
-		if (1 << fs->win[BPB_BytsPerSecEx] != SS(fs))	/* (BPB_BytsPerSecEx must be equal to the physical sector size) */
+		if (1 << fs->win[BPB_BytsPerSecEx] != SS(fs)) {	/* (BPB_BytsPerSecEx must be equal to the physical sector size) */
 			return FR_NO_FILESYSTEM;
+		}
 
 		maxlba = ld_qword(fs->win + BPB_TotSecEx) + bsect;	/* Last LBA + 1 of the volume */
 		if (maxlba >= 0x100000000) return FR_NO_FILESYSTEM;	/* (It cannot be handled in 32-bit LBA) */
@@ -3062,49 +3115,49 @@ FRESULT find_volume (	/* FR_OK(0): successful, !=0: any error occurred */
 	{
 		if (ld_word(fs->win + BPB_BytsPerSec) != SS(fs)) return FR_NO_FILESYSTEM;	/* (BPB_BytsPerSec must be equal to the physical sector size) */
 
-		fasize = ld_word(fs->win + BPB_FATSz16);			/* Number of sectors per FAT */
+		fasize = ld_word(fs->win + BPB_FATSz16);		/* Number of sectors per FAT */
 		if (fasize == 0) fasize = ld_dword(fs->win + BPB_FATSz32);
 		fs->fsize = fasize;
 
-		fs->n_fats = fs->win[BPB_NumFATs];					/* Number of FATs */
+		fs->n_fats = fs->win[BPB_NumFATs];				/* Number of FATs */
 		if (fs->n_fats != 1 && fs->n_fats != 2) return FR_NO_FILESYSTEM;	/* (Must be 1 or 2) */
-		fasize *= fs->n_fats;								/* Number of sectors for FAT area */
+		fasize *= fs->n_fats;							/* Number of sectors for FAT area */
 
-		fs->csize = fs->win[BPB_SecPerClus];				/* Cluster size */
+		fs->csize = fs->win[BPB_SecPerClus];			/* Cluster size */
 		if (fs->csize == 0 || (fs->csize & (fs->csize - 1))) return FR_NO_FILESYSTEM;	/* (Must be power of 2) */
 
 		fs->n_rootdir = ld_word(fs->win + BPB_RootEntCnt);	/* Number of root directory entries */
 		if (fs->n_rootdir % (SS(fs) / SZDIRE)) return FR_NO_FILESYSTEM;	/* (Must be sector aligned) */
 
-		tsect = ld_word(fs->win + BPB_TotSec16);			/* Number of sectors on the volume */
+		tsect = ld_word(fs->win + BPB_TotSec16);		/* Number of sectors on the volume */
 		if (tsect == 0) tsect = ld_dword(fs->win + BPB_TotSec32);
 
-		nrsv = ld_word(fs->win + BPB_RsvdSecCnt);			/* Number of reserved sectors */
-		if (nrsv == 0) return FR_NO_FILESYSTEM;				/* (Must not be 0) */
+		nrsv = ld_word(fs->win + BPB_RsvdSecCnt);		/* Number of reserved sectors */
+		if (nrsv == 0) return FR_NO_FILESYSTEM;			/* (Must not be 0) */
 
 		/* Determine the FAT sub type */
 		sysect = nrsv + fasize + fs->n_rootdir / (SS(fs) / SZDIRE);	/* RSV + FAT + DIR */
-		if (tsect < sysect) return FR_NO_FILESYSTEM;		/* (Invalid volume size) */
-		nclst = (tsect - sysect) / fs->csize;				/* Number of clusters */
-		if (nclst == 0) return FR_NO_FILESYSTEM;			/* (Invalid volume size) */
+		if (tsect < sysect) return FR_NO_FILESYSTEM;	/* (Invalid volume size) */
+		nclst = (tsect - sysect) / fs->csize;			/* Number of clusters */
+		if (nclst == 0) return FR_NO_FILESYSTEM;		/* (Invalid volume size) */
 		fmt = FS_FAT32;
 		if (nclst <= MAX_FAT16) fmt = FS_FAT16;
 		if (nclst <= MAX_FAT12) fmt = FS_FAT12;
 
 		/* Boundaries and Limits */
-		fs->n_fatent = nclst + 2;							/* Number of FAT entries */
-		fs->volbase = bsect;								/* Volume start sector */
-		fs->fatbase = bsect + nrsv; 						/* FAT start sector */
-		fs->database = bsect + sysect;						/* Data start sector */
+		fs->n_fatent = nclst + 2;						/* Number of FAT entries */
+		fs->volbase = bsect;							/* Volume start sector */
+		fs->fatbase = bsect + nrsv; 					/* FAT start sector */
+		fs->database = bsect + sysect;					/* Data start sector */
 		if (fmt == FS_FAT32) {
 			if (ld_word(fs->win + BPB_FSVer32) != 0) return FR_NO_FILESYSTEM;	/* (Must be FAT32 revision 0.0) */
-			if (fs->n_rootdir) return FR_NO_FILESYSTEM;		/* (BPB_RootEntCnt must be 0) */
+			if (fs->n_rootdir) return FR_NO_FILESYSTEM;	/* (BPB_RootEntCnt must be 0) */
 			fs->dirbase = ld_dword(fs->win + BPB_RootClus32);	/* Root directory start cluster */
-			szbfat = fs->n_fatent * 4;						/* (Needed FAT size) */
+			szbfat = fs->n_fatent * 4;					/* (Needed FAT size) */
 		} else {
 			if (fs->n_rootdir == 0)	return FR_NO_FILESYSTEM;/* (BPB_RootEntCnt must not be 0) */
-			fs->dirbase = fs->fatbase + fasize;				/* Root directory start sector */
-			szbfat = (fmt == FS_FAT16) ?					/* (Needed FAT size) */
+			fs->dirbase = fs->fatbase + fasize;			/* Root directory start sector */
+			szbfat = (fmt == FS_FAT16) ?				/* (Needed FAT size) */
 				fs->n_fatent * 2 : fs->n_fatent * 3 / 2 + (fs->n_fatent & 1);
 		}
 		if (fs->fsize < (szbfat + (SS(fs) - 1)) / SS(fs)) return FR_NO_FILESYSTEM;	/* (BPB_FATSz must not be less than the size needed) */
@@ -3135,18 +3188,18 @@ FRESULT find_volume (	/* FR_OK(0): successful, !=0: any error occurred */
 #endif	/* !_FS_READONLY */
 	}
 
-	fs->fs_type = fmt;	/* FAT sub-type */
-	fs->id = ++Fsid;	/* File system mount ID */
+	fs->fs_type = fmt;		/* FAT sub-type */
+	fs->id = ++Fsid;		/* File system mount ID */
 #if _USE_LFN == 1
 	fs->lfnbuf = LfnBuf;	/* Static LFN working buffer */
 #if _FS_EXFAT
-	fs->dirbuf = DirBuf;	/* Static directory block working buuffer */
+	fs->dirbuf = DirBuf;	/* Static directory block scratchpad buuffer */
 #endif
 #endif
 #if _FS_RPATH != 0
-	fs->cdir = 0;		/* Initialize current directory */
+	fs->cdir = 0;			/* Initialize current directory */
 #endif
-#if _FS_LOCK != 0		/* Clear file lock semaphores */
+#if _FS_LOCK != 0			/* Clear file lock semaphores */
 	clear_lock(fs);
 #endif
 	return FR_OK;
@@ -3167,14 +3220,13 @@ FRESULT validate (	/* Returns FR_OK or FR_INVALID_OBJECT */
 {
 	FRESULT res;
 
-
 	if (!obj || !obj->fs || !obj->fs->fs_type || obj->fs->id != obj->id || (disk_status(obj->fs->drv) & STA_NOINIT)) {
-		*fs = 0;				/* The object is invalid */
-		res = FR_INVALID_OBJECT;
+		*fs = 0;
+		res = FR_INVALID_OBJECT;	/* The object is invalid */
 	} else {
 		*fs = obj->fs;			/* Owner file sytem object */
 		ENTER_FF(obj->fs);		/* Lock file system */
-		res = FR_OK;
+		res = FR_OK;			/* Valid object */
 	}
 	return res;
 }
@@ -3281,12 +3333,13 @@ FRESULT f_open (
 		/* Create or Open a file */
 		if (mode & (FA_CREATE_ALWAYS | FA_OPEN_ALWAYS | FA_CREATE_NEW)) {
 			if (res != FR_OK) {					/* No file, create new */
-				if (res == FR_NO_FILE)			/* There is no file to open, create a new entry */
+				if (res == FR_NO_FILE) {		/* There is no file to open, create a new entry */
 #if _FS_LOCK != 0
 					res = enq_lock() ? dir_register(&dj) : FR_TOO_MANY_OPEN_FILES;
 #else
 					res = dir_register(&dj);
 #endif
+				}
 				mode |= FA_CREATE_ALWAYS;		/* File is created */
 			}
 			else {								/* Any object is already existing */
@@ -3305,6 +3358,7 @@ FRESULT f_open (
 					fp->obj.sclust = ld_dword(fs->dirbuf + XDIR_FstClus);
 					fp->obj.objsize = ld_qword(fs->dirbuf + XDIR_FileSize);
 					fp->obj.stat = fs->dirbuf[XDIR_GenFlags] & 2;
+					fp->obj.n_frag = 0;
 					/* Initialize directory entry block */
 					st_dword(fs->dirbuf + XDIR_CrtTime, dw);	/* Set created time */
 					fs->dirbuf[XDIR_CrtTime10] = 0;
@@ -3379,16 +3433,16 @@ FRESULT f_open (
 		if (res == FR_OK) {
 #if _FS_EXFAT
 			if (fs->fs_type == FS_EXFAT) {
-				fp->obj.sclust = ld_dword(fs->dirbuf + XDIR_FstClus);		/* Get allocation info */
-				fp->obj.objsize = ld_qword(fs->dirbuf + XDIR_FileSize);
-				fp->obj.stat = fs->dirbuf[XDIR_GenFlags] & 2;
-				fp->obj.c_scl = dj.obj.sclust;
+				fp->obj.c_scl = dj.obj.sclust;							/* Get containing directory info */
 				fp->obj.c_size = ((DWORD)dj.obj.objsize & 0xFFFFFF00) | dj.obj.stat;
 				fp->obj.c_ofs = dj.blk_ofs;
+				fp->obj.sclust = ld_dword(fs->dirbuf + XDIR_FstClus);	/* Get object allocation info */
+				fp->obj.objsize = ld_qword(fs->dirbuf + XDIR_FileSize);
+				fp->obj.stat = fs->dirbuf[XDIR_GenFlags] & 2;
 			} else
 #endif
 			{
-				fp->obj.sclust = ld_clust(fs, dj.dir);				/* Get allocation info */
+				fp->obj.sclust = ld_clust(fs, dj.dir);					/* Get object allocation info */
 				fp->obj.objsize = ld_dword(dj.dir + DIR_FileSize);
 			}
 #if _USE_FASTSEEK
@@ -3672,8 +3726,10 @@ FRESULT f_sync (
 	FATFS *fs;
 	DWORD tm;
 	BYTE *dir;
+#if _FS_EXFAT
+	DIR dj;
 	DEF_NAMBUF
-
+#endif
 
 	res = validate(&fp->obj, &fs);	/* Check validity of the file object */
 	if (res == FR_OK) {
@@ -3688,10 +3744,11 @@ FRESULT f_sync (
 			tm = GET_FATTIME();				/* Modified time */
 #if _FS_EXFAT
 			if (fs->fs_type == FS_EXFAT) {
-				res = fill_fat_chain(&fp->obj);	/* Create FAT chain if needed */
+				res = fill_first_frag(&fp->obj);	/* Fill first fragment on the FAT if needed */
+				if (res == FR_OK) {
+					res = fill_last_frag(&fp->obj, fp->clust, 0xFFFFFFFF);	/* Fill last fragment on the FAT if needed */
+				}
 				if (res == FR_OK) {
-					DIR dj;
-
 					INIT_NAMBUF(fs);
 					res = load_obj_dir(&dj, &fp->obj);	/* Load directory entry block */
 					if (res == FR_OK) {
@@ -3944,7 +4001,14 @@ FRESULT f_lseek (
 #endif
 
 	res = validate(&fp->obj, &fs);		/* Check validity of the file object */
-	if (res != FR_OK || (res = (FRESULT)fp->err) != FR_OK) LEAVE_FF(fs, res);	/* Check validity */
+	if (res == FR_OK) res = (FRESULT)fp->err;
+#if _FS_EXFAT && !_FS_READONLY
+	if (res == FR_OK && fs->fs_type == FS_EXFAT) {
+		res = fill_last_frag(&fp->obj, fp->clust, 0xFFFFFFFF);	/* Fill last fragment on the FAT if needed */
+	}
+#endif
+	if (res != FR_OK) LEAVE_FF(fs, res);
+
 #if _USE_FASTSEEK
 	if (fp->cltbl) {	/* Fast seek */
 		if (ofs == CREATE_LINKMAP) {	/* Create CLMT */
@@ -4109,16 +4173,16 @@ FRESULT f_opendir (
 				if (obj->attr & AM_DIR) {		/* This object is a sub-directory */
 #if _FS_EXFAT
 					if (fs->fs_type == FS_EXFAT) {
-						obj->c_scl = obj->sclust;	/* Save containing directory inforamation */
+						obj->c_scl = obj->sclust;							/* Get containing directory inforamation */
 						obj->c_size = ((DWORD)obj->objsize & 0xFFFFFF00) | obj->stat;
 						obj->c_ofs = dp->blk_ofs;
-						obj->sclust = ld_dword(fs->dirbuf + XDIR_FstClus);	/* Get object location and status */
+						obj->sclust = ld_dword(fs->dirbuf + XDIR_FstClus);	/* Get object allocation info */
 						obj->objsize = ld_qword(fs->dirbuf + XDIR_FileSize);
 						obj->stat = fs->dirbuf[XDIR_GenFlags] & 2;
 					} else
 #endif
 					{
-						obj->sclust = ld_clust(fs, dp->dir);	/* Get object location */
+						obj->sclust = ld_clust(fs, dp->dir);	/* Get object allocation info */
 					}
 				} else {						/* This object is a file */
 					res = FR_NO_PATH;
@@ -4410,7 +4474,7 @@ FRESULT f_truncate (
 	if (res != FR_OK || (res = (FRESULT)fp->err) != FR_OK) LEAVE_FF(fs, res);
 	if (!(fp->flag & FA_WRITE)) LEAVE_FF(fs, FR_DENIED);	/* Check access mode */
 
-	if (fp->obj.objsize > fp->fptr) {
+	if (fp->fptr < fp->obj.objsize) {	/* Process when fptr is not on the eof */
 		if (fp->fptr == 0) {	/* When set file size to zero, remove entire cluster chain */
 			res = remove_chain(&fp->obj, fp->obj.sclust, 0);
 			fp->obj.sclust = 0;
@@ -4493,7 +4557,7 @@ FRESULT f_unlink (
 				{
 					dclst = ld_clust(fs, dj.dir);
 				}
-				if (dj.obj.attr & AM_DIR) {			/* Is it a sub-directory ? */
+				if (dj.obj.attr & AM_DIR) {			/* Is it a sub-directory? */
 #if _FS_RPATH != 0
 					if (dclst == fs->cdir) {		 		/* Is it the current directory? */
 						res = FR_DENIED;
@@ -4597,7 +4661,9 @@ FRESULT f_mkdir (
 					mem_set(dir, 0, SS(fs));
 				}
 			}
-			if (res == FR_OK) res = dir_register(&dj);	/* Register the object to the directoy */
+			if (res == FR_OK) {
+				res = dir_register(&dj);	/* Register the object to the directoy */
+			}
 			if (res == FR_OK) {
 #if _FS_EXFAT
 				if (fs->fs_type == FS_EXFAT) {	/* Initialize directory entry block */
@@ -4617,7 +4683,9 @@ FRESULT f_mkdir (
 					dir[DIR_Attr] = AM_DIR;				/* Attribute */
 					fs->wflag = 1;
 				}
-				if (res == FR_OK) res = sync_fs(fs);
+				if (res == FR_OK) {
+					res = sync_fs(fs);
+				}
 			} else {
 				remove_chain(&dj.obj, dcl, 0);		/* Could not register, remove cluster chain */
 			}
@@ -4648,7 +4716,7 @@ FRESULT f_rename (
 	DEF_NAMBUF
 
 
-	get_ldnumber(&path_new);						/* Ignore drive number of new name */
+	get_ldnumber(&path_new);						/* Snip drive number of new name off */
 	res = find_volume(&path_old, &fs, FA_WRITE);	/* Get logical drive of the old object */
 	if (res == FR_OK) {
 		djo.obj.fs = fs;
@@ -4656,7 +4724,9 @@ FRESULT f_rename (
 		res = follow_path(&djo, path_old);		/* Check old object */
 		if (res == FR_OK && (djo.fn[NSFLAG] & (NS_DOT | NS_NONAME))) res = FR_INVALID_NAME;	/* Check validity of name */
 #if _FS_LOCK != 0
-		if (res == FR_OK) res = chk_lock(&djo, 2);
+		if (res == FR_OK) {
+			res = chk_lock(&djo, 2);
+		}
 #endif
 		if (res == FR_OK) {						/* Object to be renamed is found */
 #if _FS_EXFAT
@@ -4678,7 +4748,7 @@ FRESULT f_rename (
 						mem_cpy(fs->dirbuf, buf, SZDIRE * 2);
 						fs->dirbuf[XDIR_NumSec] = nf; fs->dirbuf[XDIR_NumName] = nn;
 						st_word(fs->dirbuf + XDIR_NameHash, nh);
-/* Start of critical section where any interruption can cause a cross-link */
+/* Start of critical section where an interruption can cause a cross-link */
 						res = store_xdir(&djn);
 					}
 				}
@@ -4703,7 +4773,7 @@ FRESULT f_rename (
 							if (!dw) {
 								res = FR_INT_ERR;
 							} else {
-/* Start of critical section where any interruption can cause a cross-link */
+/* Start of critical section where an interruption can cause a cross-link */
 								res = move_window(fs, dw);
 								dir = fs->win + SZDIRE * 1;	/* Ptr to .. entry */
 								if (res == FR_OK && dir[1] == '.') {
@@ -4721,7 +4791,7 @@ FRESULT f_rename (
 					res = sync_fs(fs);
 				}
 			}
-/* End of critical section */
+/* End of the critical section */
 		}
 		FREE_NAMBUF();
 	}
@@ -4771,7 +4841,9 @@ FRESULT f_chmod (
 				dj.dir[DIR_Attr] = (attr & mask) | (dj.dir[DIR_Attr] & (BYTE)~mask);	/* Apply attribute change */
 				fs->wflag = 1;
 			}
-			if (res == FR_OK) res = sync_fs(fs);
+			if (res == FR_OK) {
+				res = sync_fs(fs);
+			}
 		}
 		FREE_NAMBUF();
 	}
@@ -4814,7 +4886,9 @@ FRESULT f_utime (
 				st_dword(dj.dir + DIR_ModTime, (DWORD)fno->fdate << 16 | fno->ftime);
 				fs->wflag = 1;
 			}
-			if (res == FR_OK) res = sync_fs(fs);
+			if (res == FR_OK) {
+				res = sync_fs(fs);
+			}
 		}
 		FREE_NAMBUF();
 	}
@@ -4902,9 +4976,14 @@ FRESULT f_getlabel (
 		res = move_window(fs, fs->volbase);
 		if (res == FR_OK) {
 			switch (fs->fs_type) {
-			case FS_EXFAT: di = BPB_VolIDEx; break;
-			case FS_FAT32: di = BS_VolID32; break;
-			default:       di = BS_VolID;
+			case FS_EXFAT:
+				di = BPB_VolIDEx; break;
+
+			case FS_FAT32:
+				di = BS_VolID32; break;
+
+			default:
+				di = BS_VolID;
 			}
 			*vsn = ld_dword(fs->win + di);
 		}
@@ -5074,11 +5153,11 @@ FRESULT f_expand (
 		scl = find_bitmap(fs, stcl, tcl);			/* Find a contiguous cluster block */
 		if (scl == 0) res = FR_DENIED;				/* No contiguous cluster block was found */
 		if (scl == 0xFFFFFFFF) res = FR_DISK_ERR;
-		if (res == FR_OK) {
-			if (opt) {
+		if (res == FR_OK) {	/* A contiguous free area is found */
+			if (opt) {		/* Allocate it now */
 				res = change_bitmap(fs, scl, tcl, 1);	/* Mark the cluster block 'in use' */
 				lclst = scl + tcl - 1;
-			} else {
+			} else {		/* Set it as suggested point for next allocation */
 				lclst = scl - 1;
 			}
 		}
@@ -5098,14 +5177,14 @@ FRESULT f_expand (
 			}
 			if (clst == stcl) { res = FR_DENIED; break; }	/* No contiguous cluster? */
 		}
-		if (res == FR_OK) {
-			if (opt) {
+		if (res == FR_OK) {	/* A contiguous free area is found */
+			if (opt) {		/* Allocate it now */
 				for (clst = scl, n = tcl; n; clst++, n--) {	/* Create a cluster chain on the FAT */
 					res = put_fat(fs, clst, (n == 1) ? 0xFFFFFFFF : clst + 1);
 					if (res != FR_OK) break;
 					lclst = clst;
 				}
-			} else {
+			} else {		/* Set it as suggested point for next allocation */
 				lclst = scl - 1;
 			}
 		}
@@ -5113,12 +5192,12 @@ FRESULT f_expand (
 
 	if (res == FR_OK) {
 		fs->last_clst = lclst;		/* Set suggested start cluster to start next */
-		if (opt) {
+		if (opt) {	/* Is it allocated now? */
 			fp->obj.sclust = scl;		/* Update object allocation information */
 			fp->obj.objsize = fsz;
 			if (_FS_EXFAT) fp->obj.stat = 2;	/* Set status 'contiguous chain' */
 			fp->flag |= FA_MODIFIED;
-			if (fs->free_clst  < fs->n_fatent - 2) {	/* Update FSINFO */
+			if (fs->free_clst <= fs->n_fatent - 2) {	/* Update FSINFO */
 				fs->free_clst -= tcl;
 				fs->fsi_flag |= 1;
 			}
@@ -5205,13 +5284,13 @@ FRESULT f_forward (
 
 #if _USE_MKFS && !_FS_READONLY
 /*-----------------------------------------------------------------------*/
-/* Create FAT file system on the logical drive                           */
+/* Create an FAT/exFAT volume                                            */
 /*-----------------------------------------------------------------------*/
 
 FRESULT f_mkfs (
 	const TCHAR* path,	/* Logical drive number */
 	BYTE opt,			/* Format option */
-	DWORD au,			/* Size of allocation unit [byte] */
+	DWORD au,			/* Size of allocation unit (cluster) [byte] */
 	void* work,			/* Pointer to working buffer */
 	UINT len			/* Size of working buffer */
 )
@@ -5236,7 +5315,7 @@ FRESULT f_mkfs (
 	/* Check mounted drive and clear work area */
 	vol = get_ldnumber(&path);					/* Get target logical drive */
 	if (vol < 0) return FR_INVALID_DRIVE;
-	if (FatFs[vol]) FatFs[vol]->fs_type = 0;	/* Clear mounted volume */
+	if (FatFs[vol]) FatFs[vol]->fs_type = 0;	/* Clear the volume */
 	pdrv = LD2PD(vol);	/* Physical drive */
 	part = LD2PT(vol);	/* Partition (0:create as new, 1-4:get from partition table) */
 
@@ -5245,7 +5324,7 @@ FRESULT f_mkfs (
 	if (stat & STA_NOINIT) return FR_NOT_READY;
 	if (stat & STA_PROTECT) return FR_WRITE_PROTECTED;
 	if (disk_ioctl(pdrv, GET_BLOCK_SIZE, &sz_blk) != RES_OK || !sz_blk || sz_blk > 32768 || (sz_blk & (sz_blk - 1))) sz_blk = 1;	/* Erase block to align data area */
-#if _MAX_SS != _MIN_SS		/* Get sector size of the medium */
+#if _MAX_SS != _MIN_SS		/* Get sector size of the medium if variable sector size cfg. */
 	if (disk_ioctl(pdrv, GET_SECTOR_SIZE, &ss) != RES_OK) return FR_DISK_ERR;
 	if (ss > _MAX_SS || ss < _MIN_SS || (ss & (ss - 1))) return FR_DISK_ERR;
 #else
@@ -5304,7 +5383,7 @@ FRESULT f_mkfs (
 
 		if (sz_vol < 0x1000) return FR_MKFS_ABORTED;	/* Too small volume? */
 #if _USE_TRIM
-		tbl[0] = b_vol; tbl[1] = b_vol + sz_vol - 1;	/* Inform the device the volume area can be erased */
+		tbl[0] = b_vol; tbl[1] = b_vol + sz_vol - 1;	/* Inform the device the volume area may be erased */
 		disk_ioctl(pdrv, CTRL_TRIM, tbl);
 #endif
 		/* Determine FAT location, data location and number of clusters */
@@ -5340,11 +5419,12 @@ FRESULT f_mkfs (
 					ch = 0xFFFF; st = 2; break;	/* Compress the no-case block if run is >= 128 */
 				}
 				st = 1;			/* Do not compress short run */
-				/* continue */
+				/* go to next case */
 			case 1:
 				ch = si++;		/* Fill the short run */
 				if (--j == 0) st = 0;
 				break;
+
 			default:
 				ch = (WCHAR)j; si += j;	/* Number of chars to skip */
 				st = 0;
@@ -5626,14 +5706,14 @@ FRESULT f_mkfs (
 		}
 	}
 
-	if (_MULTI_PARTITION && part != 0) {
+	/* Update partition information */
+	if (_MULTI_PARTITION && part != 0) {	/* Created in the existing partition */
 		/* Update system ID in the partition table */
 		if (disk_read(pdrv, buf, 0, 1) != RES_OK) return FR_DISK_ERR;	/* Read the MBR */
-		buf[MBR_Table + (part - 1) * SZ_PTE + PTE_System] = sys;		/* Set system type */
+		buf[MBR_Table + (part - 1) * SZ_PTE + PTE_System] = sys;		/* Set system ID */
 		if (disk_write(pdrv, buf, 0, 1) != RES_OK) return FR_DISK_ERR;	/* Write it back to the MBR */
-	} else {
-		if (!(opt & FM_SFD)) {
-			/* Create partition table in FDISK format */
+	} else {								/* Created as a new single partition */
+		if (!(opt & FM_SFD)) {	/* Create partition table if in FDISK format */
 			mem_set(buf, 0, ss);
 			st_word(buf + BS_55AA, 0xAA55);		/* MBR signature */
 			pte = buf + MBR_Table;				/* Create partition table for single partition in the drive */
@@ -5642,7 +5722,7 @@ FRESULT f_mkfs (
 			pte[PTE_StSec] = 1;					/* Start sector */
 			pte[PTE_StCyl] = 0;					/* Start cylinder */
 			pte[PTE_System] = sys;				/* System type */
-			n = (b_vol + sz_vol) / (63 * 255);	/* (End CHS is incorrect) */
+			n = (b_vol + sz_vol) / (63 * 255);	/* (End CHS may be invalid) */
 			pte[PTE_EdHead] = 254;				/* End head */
 			pte[PTE_EdSec] = (BYTE)(n >> 2 | 63);	/* End sector */
 			pte[PTE_EdCyl] = (BYTE)n;			/* End cylinder */
@@ -5681,7 +5761,7 @@ FRESULT f_fdisk (
 	if (stat & STA_PROTECT) return FR_WRITE_PROTECTED;
 	if (disk_ioctl(pdrv, GET_SECTOR_COUNT, &sz_disk)) return FR_DISK_ERR;
 
-	/* Determine the CHS without any care of the drive geometry */
+	/* Determine the CHS without any consideration of the drive geometry */
 	for (n = 16; n < 256 && sz_disk / n / 63 > 1024; n *= 2) ;
 	if (n == 256) n--;
 	e_hd = n - 1;
@@ -5692,7 +5772,7 @@ FRESULT f_fdisk (
 	mem_set(buf, 0, _MAX_SS);
 	p = buf + MBR_Table; b_cyl = 0;
 	for (i = 0; i < 4; i++, p += SZ_PTE) {
-		p_cyl = (szt[i] <= 100U) ? (DWORD)tot_cyl * szt[i] / 100 : szt[i] / sz_cyl;
+		p_cyl = (szt[i] <= 100U) ? (DWORD)tot_cyl * szt[i] / 100 : szt[i] / sz_cyl;	/* Number of cylinders */
 		if (!p_cyl) continue;
 		s_part = (DWORD)sz_cyl * b_cyl;
 		sz_part = (DWORD)sz_cyl * p_cyl;
@@ -5702,19 +5782,19 @@ FRESULT f_fdisk (
 		} else {
 			s_hd = 0;
 		}
-		e_cyl = b_cyl + p_cyl - 1;
+		e_cyl = b_cyl + p_cyl - 1;	/* End cylinder */
 		if (e_cyl >= tot_cyl) return FR_INVALID_PARAMETER;
 
 		/* Set partition table */
 		p[1] = s_hd;						/* Start head */
 		p[2] = (BYTE)((b_cyl >> 2) + 1);	/* Start sector */
 		p[3] = (BYTE)b_cyl;					/* Start cylinder */
-		p[4] = 0x06;						/* System type (temporary setting) */
+		p[4] = 0x07;						/* System type (temporary setting) */
 		p[5] = e_hd;						/* End head */
 		p[6] = (BYTE)((e_cyl >> 2) + 63);	/* End sector */
 		p[7] = (BYTE)e_cyl;					/* End cylinder */
 		st_dword(p + 8, s_part);			/* Start sector in LBA */
-		st_dword(p + 12, sz_part);			/* Partition size */
+		st_dword(p + 12, sz_part);			/* Number of sectors */
 
 		/* Next partition */
 		b_cyl += p_cyl;
@@ -5756,17 +5836,17 @@ TCHAR* f_gets (
 		c = s[0];
 		if (c >= 0x80) {
 			if (c < 0xC0) continue;	/* Skip stray trailer */
-			if (c < 0xE0) {			/* Two-byte sequence */
+			if (c < 0xE0) {			/* Two-byte sequence (0x80-0x7FF) */
 				f_read(fp, s, 1, &rc);
 				if (rc != 1) break;
 				c = (c & 0x1F) << 6 | (s[0] & 0x3F);
-				if (c < 0x80) c = '?';
+				if (c < 0x80) c = '?';	/* Reject invalid code range */
 			} else {
-				if (c < 0xF0) {		/* Three-byte sequence */
+				if (c < 0xF0) {		/* Three-byte sequence (0x800-0xFFFF) */
 					f_read(fp, s, 2, &rc);
 					if (rc != 2) break;
 					c = c << 12 | (s[0] & 0x3F) << 6 | (s[1] & 0x3F);
-					if (c < 0x800) c = '?';
+					if (c < 0x800) c = '?';	/* Reject invalid code range */
 				} else {			/* Reject four-byte sequence */
 					c = '?';
 				}
@@ -5998,17 +6078,23 @@ int f_printf (
 			while (*p) putc_bfd(&pb, *p++);
 			while (j++ < w) putc_bfd(&pb, ' ');
 			continue;
+
 		case 'C' :					/* Character */
 			putc_bfd(&pb, (TCHAR)va_arg(arp, int)); continue;
+
 		case 'B' :					/* Binary */
 			r = 2; break;
+
 		case 'O' :					/* Octal */
 			r = 8; break;
+
 		case 'D' :					/* Signed decimal */
 		case 'U' :					/* Unsigned decimal */
 			r = 10; break;
+
 		case 'X' :					/* Hexdecimal */
 			r = 16; break;
+
 		default:					/* Unknown type (pass-through) */
 			putc_bfd(&pb, c); continue;
 		}
@@ -6028,7 +6114,9 @@ int f_printf (
 		if (f & 8) str[i++] = '-';
 		j = i; d = (f & 1) ? '0' : ' ';
 		while (!(f & 2) && j++ < w) putc_bfd(&pb, d);
-		do putc_bfd(&pb, str[--i]); while (i);
+		do {
+			putc_bfd(&pb, str[--i]);
+		} while (i);
 		while (j++ < w) putc_bfd(&pb, d);
 	}
 
diff --git a/src/ff.h b/src/ff.h
index 981a886..f902519 100644
--- a/src/ff.h
+++ b/src/ff.h
@@ -1,8 +1,8 @@
 /*----------------------------------------------------------------------------/
-/  FatFs - Generic FAT file system module  R0.12b                             /
+/  FatFs - Generic FAT file system module  R0.12c                             /
 /-----------------------------------------------------------------------------/
 /
-/ Copyright (C) 2016, ChaN, all right reserved.
+/ Copyright (C) 2017, 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
@@ -19,7 +19,7 @@
 
 
 #ifndef _FATFS
-#define _FATFS	68020	/* Revision ID */
+#define _FATFS	68300	/* Revision ID */
 
 #ifdef __cplusplus
 extern "C" {
@@ -42,13 +42,6 @@ typedef struct {
 	BYTE pt;	/* Partition: 0:Auto detect, 1-4:Forced partition) */
 } PARTITION;
 extern PARTITION VolToPart[];	/* Volume - Partition resolution table */
-#define LD2PD(vol) (VolToPart[vol].pd)	/* Get physical drive number */
-#define LD2PT(vol) (VolToPart[vol].pt)	/* Get partition index */
-
-#else							/* Single partition configuration */
-#define LD2PD(vol) (BYTE)(vol)	/* Each logical drive is bound to the same physical drive number */
-#define LD2PT(vol) 0			/* Find first valid partition or in SFD */
-
 #endif
 
 
@@ -140,14 +133,15 @@ typedef struct {
 	FATFS*	fs;			/* Pointer to the owner file system object */
 	WORD	id;			/* Owner file system mount ID */
 	BYTE	attr;		/* Object attribute */
-	BYTE	stat;		/* Object chain status (b1-0: =0:not contiguous, =2:contiguous (no data on FAT), =3:got flagmented, b2:sub-directory stretched) */
+	BYTE	stat;		/* Object chain status (b1-0: =0:not contiguous, =2:contiguous (no data on FAT), =3:flagmented in this session, b2:sub-directory stretched) */
 	DWORD	sclust;		/* Object start cluster (0:no cluster or root directory) */
 	FSIZE_t	objsize;	/* Object size (valid when sclust != 0) */
 #if _FS_EXFAT
-	DWORD	n_cont;		/* Size of coutiguous part, clusters - 1 (valid when stat == 3) */
+	DWORD	n_cont;		/* Size of first fragment, clusters - 1 (valid when stat == 3) */
+	DWORD	n_frag;		/* Size of last fragment needs to be written (valid when not zero) */
 	DWORD	c_scl;		/* Containing directory start cluster (valid when sclust != 0) */
 	DWORD	c_size;		/* b31-b8:Size of containing directory, b7-b0: Chain status (valid when c_scl != 0) */
-	DWORD	c_ofs;		/* Offset in the containing directory (valid when sclust != 0) */
+	DWORD	c_ofs;		/* Offset in the containing directory (valid when sclust != 0 and non-directory object) */
 #endif
 #if _FS_LOCK != 0
 	UINT	lockid;		/* File lock ID origin from 1 (index of file semaphore table Files[]) */
@@ -163,7 +157,7 @@ typedef struct {
 	BYTE	flag;			/* File status flags */
 	BYTE	err;			/* Abort flag (error code) */
 	FSIZE_t	fptr;			/* File read/write pointer (Zeroed on file open) */
-	DWORD	clust;			/* Current cluster of fpter (invalid when fprt is 0) */
+	DWORD	clust;			/* Current cluster of fpter (invalid when fptr is 0) */
 	DWORD	sect;			/* Sector number appearing in buf[] (0:invalid) */
 #if !_FS_READONLY
 	DWORD	dir_sect;		/* Sector number containing the directory entry */
@@ -185,7 +179,7 @@ typedef struct {
 	_FDID	obj;			/* Object identifier */
 	DWORD	dptr;			/* Current read/write offset */
 	DWORD	clust;			/* Current cluster */
-	DWORD	sect;			/* Current sector */
+	DWORD	sect;			/* Current sector (0:Read operation has terminated) */
 	BYTE*	dir;			/* Pointer to the directory item in the win[] */
 	BYTE	fn[12];			/* SFN (in/out) {body[8],ext[3],status[1]} */
 #if _USE_LFN != 0
@@ -285,6 +279,7 @@ TCHAR* f_gets (TCHAR* buff, int len, FIL* fp);						/* Get a string from the fil
 #define f_size(fp) ((fp)->obj.objsize)
 #define f_rewind(fp) f_lseek((fp), 0)
 #define f_rewinddir(dp) f_readdir((dp), 0)
+#define f_rmdir(path) f_unlink(path)
 
 #ifndef EOF
 #define EOF (-1)
diff --git a/src/ffconf.h b/src/ffconf.h
index c43321f..8a569a6 100644
--- a/src/ffconf.h
+++ b/src/ffconf.h
@@ -2,7 +2,7 @@
 /  FatFs - FAT file system module configuration file
 /---------------------------------------------------------------------------*/
 
-#define _FFCONF 68020	/* Revision ID */
+#define _FFCONF 68300	/* Revision ID */
 
 /*---------------------------------------------------------------------------/
 / Function Configurations
@@ -73,7 +73,7 @@
 /* This option specifies the OEM code page to be used on the target system.
 /  Incorrect setting of the code page can cause a file open failure.
 /
-/   1   - ASCII (No extended character. Non-LFN cfg. only)
+/   1   - ASCII (No support of extended character. Non-LFN cfg. only)
 /   437 - U.S.
 /   720 - Arabic
 /   737 - Greek
@@ -148,7 +148,7 @@
 /---------------------------------------------------------------------------*/
 
 #define _VOLUMES	1
-/* Number of volumes (logical drives) to be used. */
+/* Number of volumes (logical drives) to be used. (1-10) */
 
 
 #define _STR_VOLUME_ID	0
@@ -172,11 +172,11 @@
 #define	_MIN_SS		512
 #define	_MAX_SS		512
 /* These options configure the range of sector size to be supported. (512, 1024,
-/  2048 or 4096) Always set both 512 for most systems, all type of memory cards and
+/  2048 or 4096) Always set both 512 for most systems, generic memory card and
 /  harddisk. But a larger value may be required for on-board flash memory and some
 /  type of optical media. When _MAX_SS is larger than _MIN_SS, FatFs is configured
-/  to variable sector size and GET_SECTOR_SIZE command must be implemented to the
-/  disk_ioctl() function. */
+/  to variable sector size and GET_SECTOR_SIZE command needs to be implemented to
+/  the disk_ioctl() function. */
 
 
 #define	_USE_TRIM	0
@@ -204,7 +204,7 @@
 
 #define	_FS_TINY	0
 /* This option switches tiny buffer configuration. (0:Normal or 1:Tiny)
-/  At the tiny configuration, size of file object (FIL) is reduced _MAX_SS bytes.
+/  At the tiny configuration, size of file object (FIL) is shrinked _MAX_SS bytes.
 /  Instead of private sector buffer eliminated from the file object, common sector
 /  buffer in the file system object (FATFS) is used for the file data transfer. */
 
@@ -212,7 +212,7 @@
 #define _FS_EXFAT	0
 /* This option switches support of exFAT file system. (0:Disable or 1:Enable)
 /  When enable exFAT, also LFN needs to be enabled. (_USE_LFN >= 1)
-/  Note that enabling exFAT discards C89 compatibility. */
+/  Note that enabling exFAT discards ANSI C (C89) compatibility. */
 
 
 #define _FS_NORTC	0
@@ -225,7 +225,7 @@
 /  defined by _NORTC_MON, _NORTC_MDAY and _NORTC_YEAR in local time.
 /  To enable timestamp function (_FS_NORTC = 0), get_fattime() function need to be
 /  added to the project to get current time form real-time clock. _NORTC_MON,
-/  _NORTC_MDAY and _NORTC_YEAR have no effect. 
+/  _NORTC_MDAY and _NORTC_YEAR have no effect.
 /  These options have no effect at read-only configuration (_FS_READONLY = 1). */
 
 
@@ -258,10 +258,11 @@
 /
 /  The _FS_TIMEOUT defines timeout period in unit of time tick.
 /  The _SYNC_t defines O/S dependent sync object type. e.g. HANDLE, ID, OS_EVENT*,
-/  SemaphoreHandle_t and etc.. A header file for O/S definitions needs to be
+/  SemaphoreHandle_t and etc. A header file for O/S definitions needs to be
 /  included somewhere in the scope of ff.h. */
 
 /* #include <windows.h>	// O/S definitions  */
 
 
+
 /*--- End of configuration options ---*/
diff --git a/src/integer.h b/src/integer.h
index 4660ed6..d8e911c 100644
--- a/src/integer.h
+++ b/src/integer.h
@@ -30,7 +30,7 @@ typedef unsigned short	WCHAR;
 typedef long			LONG;
 typedef unsigned long	DWORD;
 
-/* This type MUST be 64-bit (Remove this for C89 compatibility) */
+/* This type MUST be 64-bit (Remove this for ANSI C (C89) compatibility) */
 typedef unsigned long long QWORD;
 
 #endif
