72 lines
2.2 KiB
HTML
72 lines
2.2 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
|
|
<html lang="en">
|
|
<head>
|
|
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
|
|
<meta http-equiv="Content-Style-Type" content="text/css">
|
|
<link rel="up" title="FatFs" href="../00index_e.html">
|
|
<link rel="stylesheet" href="../css_e.css" type="text/css" media="screen" title="ELM Default">
|
|
<title>FatFs - f_read</title>
|
|
</head>
|
|
|
|
<body>
|
|
|
|
<div class="para">
|
|
<h2>f_read</h2>
|
|
<p>The f_read reads data from a file.</p>
|
|
<pre>
|
|
FRESULT f_read (
|
|
FIL* <em>FileObject</em>, // Pointer to the file object structure
|
|
void* <em>Buffer</em>, // Pointer to the buffer to store read data
|
|
WORD <em>ByteToRead</em>, // Number of bytes to read
|
|
WORD* <em>ByteRead</em> // Pointer to the variable to return number of bytes read
|
|
);
|
|
</pre>
|
|
</div>
|
|
|
|
<div class="para">
|
|
<h4>Parameters</h4>
|
|
<dl class="par">
|
|
<dt>FileObject</dt>
|
|
<dd>Pointer to the valid file object structure.</dd>
|
|
<dt>Buffer</dt>
|
|
<dd>Pointer to the buffer to store read data</dd>
|
|
<dt>ByteToRead</dt>
|
|
<dd>Number of bytes to read</dd>
|
|
<dt>ByteRead</dt>
|
|
<dd>Pointer to the WORD variable to return number of bytes read.</dd>
|
|
</dt>
|
|
</div>
|
|
|
|
|
|
<div class="para">
|
|
<h4>Return Values</h4>
|
|
<dl class="ret">
|
|
<dt>FR_OK (0)</dt>
|
|
<dd>The function succeeded.</dd>
|
|
<dt>FR_DENIED</dt>
|
|
<dd>The function denied due to the file has been opened in write only mode.</dd>
|
|
<dt>FR_RW_ERROR</dt>
|
|
<dd>Any error occured in low level disk I/O.</dd>
|
|
<dt>FR_NOT_READY</dt>
|
|
<dd>The disk drive cannot work due to no medium in the drive or any other reason.</dd>
|
|
<dt>FR_NOT_ENABLED</dt>
|
|
<dd>FatFs module is not enabled.</dd>
|
|
</dl>
|
|
</div>
|
|
|
|
|
|
<div class="para">
|
|
<h4>Description</h4>
|
|
<p>The read/write pointer increases in number of bytes read. The <tt>ByteRead</tt> will be less than <tt>ByteToRead</tt> when the read pointer reached to end of the file or any error occured during the read operation.</p>
|
|
</div>
|
|
|
|
|
|
<div class="para">
|
|
<h4>References</h4>
|
|
<p><tt><a href="open.html">f_open</a>, <a href="write.html">f_write</a>, <a href="close.html">f_close</a>, <a href="sfile.html">FIL</a></tt></p>
|
|
</div>
|
|
|
|
<p class="foot"><a href="../00index_e.html">Return</a></p>
|
|
</body>
|
|
</html>
|