+++ /dev/null
-<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">\r
-<html lang="en">\r
-<head>\r
-<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">\r
-<meta http-equiv="Content-Style-Type" content="text/css">\r
-<link rel="up" title="FatFs" href="../00index_e.html">\r
-<link rel="alternate" hreflang="ja" title="Japanese" href="../ja/dread.html">\r
-<link rel="stylesheet" href="../css_e.css" type="text/css" media="screen" title="ELM Default">\r
-<title>FatFs - disk_read</title>\r
-</head>\r
-\r
-<body>\r
-\r
-<div class="para func">\r
-<h2>disk_read</h2>\r
-<p>The disk_read function reads sector(s) from the storage device.</p>\r
-<pre>\r
-DRESULT disk_read (\r
- BYTE <span class="arg">pdrv</span>, <span class="c">/* [IN] Physical drive number */</span>\r
- BYTE* <span class="arg">buff</span>, <span class="c">/* [OUT] Pointer to the read data buffer */</span>\r
- DWORD <span class="arg">sector</span>, <span class="c">/* [IN] Start sector number */</span>\r
- UINT <span class="arg">count</span> <span class="c">/* [IN] Number of sectros to read */</span>\r
-);\r
-</pre>\r
-</div>\r
-\r
-<div class="para arg">\r
-<h4>Parameters</h4>\r
-<dl class="par">\r
-<dt>pdrv</dt>\r
-<dd>Physical drive number to identify the target device.</dd>\r
-<dt>buff</dt>\r
-<dd>Pointer to the <em>byte array</em> to store the read data.</dd>\r
-<dt>sector</dt>\r
-<dd>Start sector number in logical block address (LBA).</dd>\r
-<dt>count</dt>\r
-<dd>Number of sectors to read. FatFs specifis it in range of from 1 to 128.</dd>\r
-</dl>\r
-</div>\r
-\r
-\r
-<div class="para ret">\r
-<h4>Return Value</h4>\r
-<dl class="ret">\r
-<dt>RES_OK (0)</dt>\r
-<dd>The function succeeded.</dd>\r
-<dt>RES_ERROR</dt>\r
-<dd>Any hard error occured during the read operation and could not recover it.</dd>\r
-<dt>RES_PARERR</dt>\r
-<dd>Invalid parameter.</dd>\r
-<dt>RES_NOTRDY</dt>\r
-<dd>The device has not been initialized.</dd>\r
-</dl>\r
-</div>\r
-\r
-\r
-<div class="para desc">\r
-<h4>Description</h4>\r
-<p>The memory address specified by <tt class="arg">buff</tt> is not that always aligned to word boundary because the type of argument is defined as <tt>BYTE*</tt>. The misaligned read/write request can occure at <a href="appnote.html#fs1">direct transfer</a>. If the bus architecture, especially DMA controller, does not allow misaligned memory access, it should be solved in this function. There are some workarounds described below to avoid this issue.</p>\r
-<ul>\r
-<li>Convert word transfer to byte transfer in this function. - Recommended.</li>\r
-<li>For <tt>f_read()</tt>, avoid long read request that includes a whole of sector. - Direct transfer will never occure.</li>\r
-<li>For <tt>f_read(fp, buff, btr, &br)</tt>, make sure that <tt>(((UINT)buff & 3) == (f_tell(fp) & 3))</tt> is true. - Word aligned direct transfer is guaranteed.</li>\r
-</ul>\r
-<p>Generally, a multiple sector transfer request must not be split into single sector transactions to the storage device, or you will not get good read throughput.</p>\r
-</div>\r
-\r
-\r
-<p class="foot"><a href="../00index_e.html">Return</a></p>\r
-</body>\r
-</html>\r
projects / z180-stamp.git / blobdiff