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| <h2 id="fs_read"><font color="#F2853F" style="font-size:24pt">fs_read</font></h2> |
| <div class="codehilite" style="background: #ffffff"><pre style="line-height: 125%;"><span></span><code><span style="color: #A90D91">int</span> <span style="color: #000000">fs_read</span>(<span style="color: #A90D91">struct</span> <span style="color: #3F6E75">fs_file</span> <span style="color: #000000">*file</span>, <span style="color: #A90D91">uint32_t</span> <span style="color: #000000">len</span>, <span style="color: #A90D91">void</span> <span style="color: #000000">*out_data</span>, <span style="color: #A90D91">uint32_t</span> <span style="color: #000000">*out_len</span>) |
| </code></pre></div> |
| |
| <p>Reads data from the specified file. If more data is requested than remains in the file, all available data is retrieved and a success code is returned.</p> |
| <h4 id="arguments">Arguments</h4> |
| <table> |
| <thead> |
| <tr> |
| <th><em>Argument</em></th> |
| <th><em>Description</em></th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td>file</td> |
| <td>Pointer to the the file to read from</td> |
| </tr> |
| <tr> |
| <td>len</td> |
| <td>The number of bytes to attempt to read</td> |
| </tr> |
| <tr> |
| <td>out_data</td> |
| <td>The destination buffer to read into</td> |
| </tr> |
| <tr> |
| <td>out_len</td> |
| <td>On success, the number of bytes actually read gets written here. Pass null if you don't care.</td> |
| </tr> |
| </tbody> |
| </table> |
| <h4 id="returned-values">Returned values</h4> |
| <ul> |
| <li>0 on success</li> |
| <li><a href="../fs_return_codes/">FS error code</a> on failure</li> |
| </ul> |
| <h4 id="header-file">Header file</h4> |
| <div class="codehilite" style="background: #ffffff"><pre style="line-height: 125%;"><span></span><code><span style="color: #633820">#include</span> <span style="color: #177500">"fs/fs.h"</span> |
| </code></pre></div> |
| |
| <h4 id="example">Example</h4> |
| <p>The below code opens the file <code>/settings/config.txt</code> for reading, reads some data, and then closes the file.</p> |
| <div class="codehilite" style="background: #ffffff"><pre style="line-height: 125%;"><span></span><code><span style="color: #A90D91">int</span> |
| <span style="color: #000000">read_config</span>(<span style="color: #A90D91">void</span>) |
| { |
| <span style="color: #A90D91">struct</span> <span style="color: #3F6E75">fs_file</span> <span style="color: #000000">*file</span>; |
| <span style="color: #A90D91">uint32_t</span> <span style="color: #000000">bytes_read</span>; |
| <span style="color: #A90D91">uint8_t</span> <span style="color: #000000">buf</span>[<span style="color: #1C01CE">16</span>]; |
| <span style="color: #A90D91">int</span> <span style="color: #000000">rc</span>; |
| |
| <span style="color: #177500">/* Open the file for reading. */</span> |
| <span style="color: #000000">rc</span> <span style="color: #000000">=</span> <span style="color: #000000">fs_open</span>(<span style="color: #C41A16">"/settings/config.txt"</span>, <span style="color: #000000">FS_ACCESS_READ</span>, <span style="color: #000000">&file</span>); |
| <span style="color: #A90D91">if</span> (<span style="color: #000000">rc</span> <span style="color: #000000">!=</span> <span style="color: #1C01CE">0</span>) { |
| <span style="color: #A90D91">return</span> <span style="color: #1C01CE">-1</span>; |
| } |
| |
| <span style="color: #177500">/* Read up to 16 bytes from the file. */</span> |
| <span style="color: #000000">rc</span> <span style="color: #000000">=</span> <span style="color: #000000">fs_read</span>(<span style="color: #000000">file</span>, <span style="color: #A90D91">sizeof</span> <span style="color: #000000">buf</span>, <span style="color: #000000">buf</span>, <span style="color: #000000">&bytes_read</span>); |
| <span style="color: #A90D91">if</span> (<span style="color: #000000">rc</span> <span style="color: #000000">==</span> <span style="color: #1C01CE">0</span>) { |
| <span style="color: #177500">/* buf now contains up to 16 bytes of file data. */</span> |
| <span style="color: #000000">console_printf</span>(<span style="color: #C41A16">"read %u bytes\n"</span>, <span style="color: #000000">bytes_read</span>) |
| } |
| |
| <span style="color: #177500">/* Close the file. */</span> |
| <span style="color: #000000">fs_close</span>(<span style="color: #000000">file</span>); |
| |
| <span style="color: #A90D91">return</span> <span style="color: #000000">rc</span> <span style="color: #000000">==</span> <span style="color: #1C01CE">0</span> <span style="color: #000000">?</span> <span style="color: #1C01CE">0</span> <span style="color: #000000">:</span> <span style="color: #1C01CE">-1</span>; |
| } |
| </code></pre></div> |
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