1e6865dcdSopenharmony_ci<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> 2e6865dcdSopenharmony_ci<html lang="en"> 3e6865dcdSopenharmony_ci<head> 4e6865dcdSopenharmony_ci<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 5e6865dcdSopenharmony_ci<meta http-equiv="Content-Style-Type" content="text/css"> 6e6865dcdSopenharmony_ci<link rel="up" title="FatFs" href="../00index_e.html"> 7e6865dcdSopenharmony_ci<link rel="alternate" hreflang="ja" title="Japanese" href="../ja/read.html"> 8e6865dcdSopenharmony_ci<link rel="stylesheet" href="../css_e.css" type="text/css" media="screen" title="ELM Default"> 9e6865dcdSopenharmony_ci<title>FatFs - f_read</title> 10e6865dcdSopenharmony_ci</head> 11e6865dcdSopenharmony_ci 12e6865dcdSopenharmony_ci<body> 13e6865dcdSopenharmony_ci 14e6865dcdSopenharmony_ci<div class="para func"> 15e6865dcdSopenharmony_ci<h2>f_read</h2> 16e6865dcdSopenharmony_ci<p>The f_read function reads data from a file.</p> 17e6865dcdSopenharmony_ci<pre> 18e6865dcdSopenharmony_ciFRESULT f_read ( 19e6865dcdSopenharmony_ci FIL* <span class="arg">fp</span>, <span class="c">/* [IN] File object */</span> 20e6865dcdSopenharmony_ci void* <span class="arg">buff</span>, <span class="c">/* [OUT] Buffer to store read data */</span> 21e6865dcdSopenharmony_ci UINT <span class="arg">btr</span>, <span class="c">/* [IN] Number of bytes to read */</span> 22e6865dcdSopenharmony_ci UINT* <span class="arg">br</span> <span class="c">/* [OUT] Number of bytes read */</span> 23e6865dcdSopenharmony_ci); 24e6865dcdSopenharmony_ci</pre> 25e6865dcdSopenharmony_ci</div> 26e6865dcdSopenharmony_ci 27e6865dcdSopenharmony_ci<div class="para arg"> 28e6865dcdSopenharmony_ci<h4>Parameters</h4> 29e6865dcdSopenharmony_ci<dl class="par"> 30e6865dcdSopenharmony_ci<dt>fp</dt> 31e6865dcdSopenharmony_ci<dd>Pointer to the open file object.</dd> 32e6865dcdSopenharmony_ci<dt>buff</dt> 33e6865dcdSopenharmony_ci<dd>Pointer to the buffer to store the read data.</dd> 34e6865dcdSopenharmony_ci<dt>btr</dt> 35e6865dcdSopenharmony_ci<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> 36e6865dcdSopenharmony_ci<dt>br</dt> 37e6865dcdSopenharmony_ci<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> 38e6865dcdSopenharmony_ci</dl> 39e6865dcdSopenharmony_ci</div> 40e6865dcdSopenharmony_ci 41e6865dcdSopenharmony_ci 42e6865dcdSopenharmony_ci<div class="para ret"> 43e6865dcdSopenharmony_ci<h4>Return Values</h4> 44e6865dcdSopenharmony_ci<p> 45e6865dcdSopenharmony_ci<a href="rc.html#ok">FR_OK</a>, 46e6865dcdSopenharmony_ci<a href="rc.html#de">FR_DISK_ERR</a>, 47e6865dcdSopenharmony_ci<a href="rc.html#ie">FR_INT_ERR</a>, 48e6865dcdSopenharmony_ci<a href="rc.html#dn">FR_DENIED</a>, 49e6865dcdSopenharmony_ci<a href="rc.html#io">FR_INVALID_OBJECT</a>, 50e6865dcdSopenharmony_ci<a href="rc.html#tm">FR_TIMEOUT</a> 51e6865dcdSopenharmony_ci</p> 52e6865dcdSopenharmony_ci</div> 53e6865dcdSopenharmony_ci 54e6865dcdSopenharmony_ci 55e6865dcdSopenharmony_ci<div class="para desc"> 56e6865dcdSopenharmony_ci<h4>Description</h4> 57e6865dcdSopenharmony_ci<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> 58e6865dcdSopenharmony_ci</div> 59e6865dcdSopenharmony_ci 60e6865dcdSopenharmony_ci 61e6865dcdSopenharmony_ci<div class="para comp"> 62e6865dcdSopenharmony_ci<h4>QuickInfo</h4> 63e6865dcdSopenharmony_ci<p>Always available.</p> 64e6865dcdSopenharmony_ci</div> 65e6865dcdSopenharmony_ci 66e6865dcdSopenharmony_ci 67e6865dcdSopenharmony_ci<div class="para use"> 68e6865dcdSopenharmony_ci<h4>Example</h4> 69e6865dcdSopenharmony_ci<p>Refer to the example in <tt>f_open</tt>.</p> 70e6865dcdSopenharmony_ci</div> 71e6865dcdSopenharmony_ci 72e6865dcdSopenharmony_ci 73e6865dcdSopenharmony_ci<div class="para ref"> 74e6865dcdSopenharmony_ci<h4>See Also</h4> 75e6865dcdSopenharmony_ci<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> 76e6865dcdSopenharmony_ci</div> 77e6865dcdSopenharmony_ci 78e6865dcdSopenharmony_ci<p class="foot"><a href="../00index_e.html">Return</a></p> 79e6865dcdSopenharmony_ci</body> 80e6865dcdSopenharmony_ci</html> 81