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| <title>FatFs - f_read</title> | |
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| <div class="para"> | |
| <h2>f_read</h2> | |
| <p>The f_read function 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 */ | |
| UINT <em>ByteToRead</em>, /* Number of bytes to read */ | |
| UINT* <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 open file object.</dd> | |
| <dt>Buffer</dt> | |
| <dd>Pointer to the buffer to store read data</dd> | |
| <dt>ByteToRead</dt> | |
| <dd>Number of bytes to read in range of UINT.</dd> | |
| <dt>ByteRead</dt> | |
| <dd>Pointer to the UINT variable to return number of bytes read. The value is always valid after the function call regardless of the result.</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_DENIED</dt> | |
| <dd>The function denied due to the file has been opened in non-read mode.</dd> | |
| <dt>FR_DISK_ERR</dt> | |
| <dd>The function failed due to an error in the disk function.</dd> | |
| <dt>FR_INT_ERR</dt> | |
| <dd>The function failed due to a wrong FAT structure or an internal error.</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_INVALID_OBJECT</dt> | |
| <dd>The file object is invalid.</dd> | |
| </dl> | |
| </div> | |
| <div class="para"> | |
| <h4>Description</h4> | |
| <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 the end of file. In case of <tt>*ByteRead < ByteToRead</tt>, it means the R/W pointer reached end of the file during read operation.</p> | |
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| <h4>QuickInfo</h4> | |
| <p>Always available.</p> | |
| </div> | |
| <div class="para"> | |
| <h4>See Also</h4> | |
| <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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