📄 lseek.html
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<title>FatFs - f_lseek</title>
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<div class="para">
<h2>f_lseek</h2>
<p>The f_lseek moves the file read/write pointer.</p>
<pre>
FRESULT f_lseek (
FIL* <em>FileObject</em>, // Pointer to the file object structure
DWORD <em>Offset</em> // File offset in unit of byte
);
</pre>
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<div class="para">
<h4>Parameters</h4>
<dl class="par">
<dt>FileObject</dt>
<dd>Pointer to the file object structure.</dd>
<dt>Offset</dt>
<dd>Number of bytes where from start of file</dd>
</dl>
</div>
<div class="para">
<h4>Return Values</h4>
<dl class="ret">
<dt>FR_OK (0)</dt>
<dd>The function succeeded.</dd>
<dt>FR_RW_ERROR</dt>
<dd>Any error occured in low level disk I/O.</dd>
<dt>FR_INCORRECT_DISK_CHANGE</dt>
<dd>Incorrect disk removal, such as a medium change during any file is opend, has been occured.</dd>
<dt>FR_NOT_ENABLED</dt>
<dd>FatFs module has not been enabled.</dd>
</dl>
</div>
<div class="para">
<h4>Description</h4>
<p>The f_lseek moves the file read/write pointer. The offset can be specified in only origin from top of the file and cannot moved to above end of the file. When an offset above the file size was specified, the read/write pointer moves to end of the file.</p>
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<div class="para">
<h4>Sample Code</h4>
<pre>
// Move to offset of 5000 from top of file.
res = f_lseek(&file, 5000);
// Forward 3000 bytes
res = f_lseek(&file, file.fptr + 3000);
// Rewind 2000 bytes
res = f_lseek(&file, file.fptr - 2000);
// Move to end of file
res = f_lseek(&file, 0xFFFFFFFF);
</pre>
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<div class="para">
<h4>References</h4>
<p><tt><a href="open.html">f_open</a>, <a href="sfile.html">FIL</a></tt></p>
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<p class="foot"><a href="../00index_e.html">Return</a></p>
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