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6 <link rel="up" title="FatFs" href="../00index_e.html">
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7 <link rel="stylesheet" href="../css_e.css" type="text/css" media="screen" title="ELM Default">
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8 <title>FatFs - f_read</title>
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15 <p>The f_read function reads data from a file.</p>
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18 FIL* <em>FileObject</em>, /* Pointer to the file object structure */
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19 void* <em>Buffer</em>, /* Pointer to the buffer to store read data */
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20 UINT <em>ByteToRead</em>, /* Number of bytes to read */
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21 UINT* <em>ByteRead</em> /* Pointer to the variable to return number of bytes read */
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30 <dd>Pointer to the open file object.</dd>
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32 <dd>Pointer to the buffer to store read data</dd>
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34 <dd>Number of bytes to read in range of UINT.</dd>
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36 <dd>Pointer to the UINT variable to return number of bytes read.</dd>
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42 <h4>Return Values</h4>
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45 <dd>The function succeeded.</dd>
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47 <dd>The function denied due to the file has been opened in non-read mode.</dd>
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48 <dt>FR_DISK_ERR</dt>
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49 <dd>The function failed due to an error in the disk function.</dd>
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51 <dd>The function failed due to a wrong FAT structure or an internal error.</dd>
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52 <dt>FR_NOT_READY</dt>
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53 <dd>The disk drive cannot work due to no medium in the drive or any other reason.</dd>
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54 <dt>FR_INVALID_OBJECT</dt>
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55 <dd>The file object is invalid.</dd>
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61 <h4>Description</h4>
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62 <p>The file pointer of the file object increases in number of bytes read. After the function succeeded, <tt>*ByteRead</tt> should be checked to detect end of file. In case of <tt>*ByteRead < ByteToRead</tt>, it means the R/W pointer reached end of file during read operation.</p>
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68 <p><tt><a href="open.html">f_open</a>, <a href="gets.html">fgets</a>, <a href="write.html">f_write</a>, <a href="close.html">f_close</a>, <a href="sfile.html">FIL</a></tt></p>
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71 <p class="foot"><a href="../00index_e.html">Return</a></p>
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