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1 | <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">\r |
2 | <html lang="en">\r | |
3 | <head>\r | |
289f6a14 | 4 | <meta http-equiv="Content-Type" content="text/html; charset=utf-8">\r |
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5 | <meta http-equiv="Content-Style-Type" content="text/css">\r |
6 | <link rel="up" title="FatFs" href="../00index_e.html">\r | |
7 | <link rel="alternate" hreflang="ja" title="Japanese" href="../ja/read.html">\r | |
8 | <link rel="stylesheet" href="../css_e.css" type="text/css" media="screen" title="ELM Default">\r | |
9 | <title>FatFs - f_read</title>\r | |
10 | </head>\r | |
11 | \r | |
12 | <body>\r | |
13 | \r | |
14 | <div class="para func">\r | |
15 | <h2>f_read</h2>\r | |
16 | <p>The f_read function reads data from a file.</p>\r | |
17 | <pre>\r | |
18 | FRESULT f_read (\r | |
19 | FIL* <span class="arg">fp</span>, <span class="c">/* [IN] File object */</span>\r | |
20 | void* <span class="arg">buff</span>, <span class="c">/* [OUT] Buffer to store read data */</span>\r | |
21 | UINT <span class="arg">btr</span>, <span class="c">/* [IN] Number of bytes to read */</span>\r | |
22 | UINT* <span class="arg">br</span> <span class="c">/* [OUT] Number of bytes read */</span>\r | |
23 | );\r | |
24 | </pre>\r | |
25 | </div>\r | |
26 | \r | |
27 | <div class="para arg">\r | |
28 | <h4>Parameters</h4>\r | |
29 | <dl class="par">\r | |
30 | <dt>fp</dt>\r | |
31 | <dd>Pointer to the open file object.</dd>\r | |
32 | <dt>buff</dt>\r | |
5630b930 | 33 | <dd>Pointer to the buffer to store the read data.</dd>\r |
53668523 | 34 | <dt>btr</dt>\r |
5630b930 | 35 | <dd>Number of bytes to read in range of <tt>UINT</tt> type. If the file needs to be read fast, it should be read in large chunk as possible.</dd>\r |
53668523 | 36 | <dt>br</dt>\r |
5630b930 | 37 | <dd>Pointer to the <tt>UINT</tt> variable that receives number of bytes read. This value is always valid after the function call regardless of the function return code. If the return value is equal to <tt class="arg">btr</tt>, the function return code should be <tt>FR_OK</tt>.</dd>\r |
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38 | </dl>\r |
39 | </div>\r | |
40 | \r | |
41 | \r | |
42 | <div class="para ret">\r | |
43 | <h4>Return Values</h4>\r | |
44 | <p>\r | |
45 | <a href="rc.html#ok">FR_OK</a>,\r | |
46 | <a href="rc.html#de">FR_DISK_ERR</a>,\r | |
47 | <a href="rc.html#ie">FR_INT_ERR</a>,\r | |
289f6a14 | 48 | <a href="rc.html#dn">FR_DENIED</a>,\r |
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49 | <a href="rc.html#io">FR_INVALID_OBJECT</a>,\r |
50 | <a href="rc.html#tm">FR_TIMEOUT</a>\r | |
51 | </p>\r | |
52 | </div>\r | |
53 | \r | |
54 | \r | |
55 | <div class="para desc">\r | |
56 | <h4>Description</h4>\r | |
5630b930 | 57 | <p>The function starts to read data from the file at the file offset pointed by read/write pointer. The read/write pointer advances as number of bytes read. After the function succeeded, <tt class="arg">*br</tt> should be checked to detect end of the file. In case of <tt class="arg">*br</tt> < <tt class="arg">btr</tt>, it means the read/write pointer hit end of the file during read operation.</p>\r |
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58 | </div>\r |
59 | \r | |
60 | \r | |
61 | <div class="para comp">\r | |
62 | <h4>QuickInfo</h4>\r | |
63 | <p>Always available.</p>\r | |
64 | </div>\r | |
65 | \r | |
66 | \r | |
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67 | <div class="para use">\r |
68 | <h4>Example</h4>\r | |
69 | <p>Refer to the example in <tt>f_open</tt>.</p>\r | |
70 | </div>\r | |
71 | \r | |
72 | \r | |
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73 | <div class="para ref">\r |
74 | <h4>See Also</h4>\r | |
75 | <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>\r | |
76 | </div>\r | |
77 | \r | |
78 | <p class="foot"><a href="../00index_e.html">Return</a></p>\r | |
79 | </body>\r | |
80 | </html>\r |