savelij13
f76dc3a97f
- Improved cluster scan algolithm to write files fast. - Fixed f_mkdir() creates incorrect directory on FAT32.
134 lines
5.6 KiB
HTML
134 lines
5.6 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
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<html lang="en">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
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<meta http-equiv="Content-Style-Type" content="text/css">
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<link rel="up" title="FatFs" href="../00index_e.html">
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<link rel="stylesheet" href="../css_e.css" type="text/css" media="screen" title="ELM Default">
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<title>FatFs - f_open</title>
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</head>
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<body>
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<div class="para">
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<h2>f_open</h2>
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<p>The f_open function creates or opens the file and initialize a file object structure to be used to access the file.</p>
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<pre>
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FRESULT f_open (
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FIL* <em>FileObject</em>, // Pointer to the file object structure
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const char* <em>FileName</em>, // Pointer to the file neme
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BYTE <em>ModeFlags</em> // Mode flags
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);
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</pre>
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</div>
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<div class="para">
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<h4>Parameters</h4>
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<dl class="par">
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<dt>FileObject</dt>
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<dd>Pointer to the blank file object structure to be initialized. After the f_open() succeeded, the file can be accessed with the file object structure until it is closed.</dd>
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<dt>FileName</dt>
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<dd>Pointer to a null-terminated string specifies the full-path file name to create or open. The directory separator is <tt>'/'</tt>. Because the FatFs module does not have a concept of current directory, a full-path name that followed from the root directory must be used. Leading space charactors are skipped if exist, and heading <tt>'/'</tt> can be exist or omitted.</dd>
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<dt>ModeFlags</dt>
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<dd>Specifies the type of access and open method for the file. It is specified by a combination of following flags.<br>
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<table class="lst">
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<tr><th>Value</th><th>Description</th></tr>
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<tr><td>FA_READ</td><td>Specifies read access to the object. Data can be read from the file.<br>Combine with FA_WRITE for read-write access.</td></tr>
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<tr><td>FA_WRITE</td><td>Specifies write access to the object. Data can be written to the file.<br>Combine with FA_READ for read-write access.</td></tr>
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<tr><td>FA_OPEN_EXISTING</td><td>Opens the file. The function fails if the file is not existing.</td></tr>
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<tr><td>FA_CREATE_ALWAYS</td><td>Creates a new file. If the file is existing, it is truncated and overwritten.</td></tr>
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<tr><td>FA_OPEN_ALWAYS</td><td>Opens the file, if it is existing. If not, the function creates the new file.</td></tr>
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</table>
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</dd>
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</dl>
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</div>
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<div class="para">
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<h4>Return Values</h4>
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<dl class="ret">
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<dt>FR_OK (0)</dt>
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<dd>The function succeeded. The <tt><em>FileObject</em></tt> structure is used for subsequent calls to refer to the file. When close the file, use function <tt><a href="close.html">f_close()</a></tt>.</dd>
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<dt>FR_NO_FILE</dt>
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<dd>Could not find the file.</dd>
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<dt>FR_NO_PATH</dt>
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<dd>Could not find the path.</dd>
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<dt>FR_INVALID_NAME</dt>
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<dd>The file name is invalid.</dd>
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<dt>FR_DENIED</dt>
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<dd>The required access was denied due to any of following reasons: write mode open of a file that has read-only attribute, file creation under existing a same name directory or read-only file, cannot be created due to the directory table or disk full.</dd>
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<dt>FR_NOT_READY</dt>
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<dd>The disk drive cannot work due to no medium in the drive or any other reason.</dd>
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<dt>FR_WRITE_PROTECTED</dt>
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<dd>Write mode open or creation under the medium is write protected.</dd>
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<dt>FR_RW_ERROR</dt>
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<dd>Any error occured in low level disk I/O.</dd>
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<dt>FR_INCORRECT_DISK_CHANGE</dt>
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<dd>Incorrect disk removal/change has occured.</dd>
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<dt>FR_NOT_ENABLED</dt>
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<dd>FatFs module is not enabled.</dd>
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<dt>FR_NO_FILESYSTEM</dt>
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<dd>There is no valid FAT partition on the disk.</dd>
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</dl>
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</div>
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<div class="para">
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<h4>Description</h4>
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<p>To start FatFs module, prepare a work area (<tt>FATFS</tt> structure), fill it with zero and set its address to the global variable <em>FatFs</em> to give the work area to the FatFs module. All file functions can work after the initialization. <a href="mountdrv.html">f_mountdrv()</a> can also be used instead of the zero filling, however, the physical drive must be ready at that time. To terminate use of the FatFs module, close all files, clear <em>FatFs</em> and then the work area can be discarded.</p>
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<p>Flags <tt>FA_WRITE, FA_CREATE_ALWAYS, FA_OPEN_ALWAYS</tt> are not supported in read-only configuration.</p>
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</div>
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<div class="para">
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<h4>Example (File Copy)</h4>
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<pre>
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void main ()
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{
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FATFS fs; // FatFs work area
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FIL fsrc, fdst; // file structures
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BYTE buffer[4096]; // file copy buffer
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FRESULT res; // FatFs function common result code
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WORD br, bw; // File R/W count
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// Give a work area to FatFs module (activate FatFs module)
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FatFs = &fs;
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memset(&fs, 0, sizeof(FATFS)); // Clear work area. f_mountdrv() can also be used instead.
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// Open source file
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res = f_open(&fsrc, "srcfile.dat", FA_OPEN_EXISTING | FA_READ);
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if (res) die(res);
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// Create destination file
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res = f_open(&fdst, "dstfile.dat", FA_CREATE_ALWAYS | FA_WRITE);
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if (res) die(res);
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// Copy source to destination
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for (;;) {
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res = f_read(&fsrc, buffer, sizeof(buffer), &br);
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if (res || br == 0) break; // error or eof
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res = f_write(&fdst, buffer, br, &bw);
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if (res || bw < br) break; // error or disk full
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}
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// Close all files
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f_close(&fsrc);
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f_close(&fdst);
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// Deactivate FatFs module
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FatFs = NULL;
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}
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</pre>
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</div>
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<div class="para">
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<h4>References</h4>
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<p><tt><a href="read.html">f_read</a>, <a href="write.html">f_write</a>, <a href="close.html">f_close</a>, <a href="sfile.html">FIL</a>, <a href="sfatfs.html">FATFS</a></tt></p>
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</div>
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<p class="foot"><a href="../00index_e.html">Return</a></p>
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</body>
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</html>
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