1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>usb_calc_bus_time</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><link rel="home" href="index.html" title="The Linux-USB Host Side API"><link rel="up" href="hcd.html" title="Chapter&#160;6.&#160;Host Controller APIs"><link rel="prev" href="hcd.html" title="Chapter&#160;6.&#160;Host Controller APIs"><link rel="next" href="API-usb-hcd-link-urb-to-ep.html" title="usb_hcd_link_urb_to_ep"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><span class="phrase">usb_calc_bus_time</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="hcd.html">Prev</a>&#160;</td><th width="60%" align="center">Chapter&#160;6.&#160;Host Controller APIs</th><td width="20%" align="right">&#160;<a accesskey="n" href="API-usb-hcd-link-urb-to-ep.html">Next</a></td></tr></table><hr></div><div class="refentry"><a name="API-usb-calc-bus-time"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>usb_calc_bus_time &#8212; 
2  approximate periodic transaction time in nanoseconds
3 </p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">long <b class="fsfunc">usb_calc_bus_time </b>(</code></td><td>int <var class="pdparam">speed</var>, </td></tr><tr><td>&#160;</td><td>int <var class="pdparam">is_input</var>, </td></tr><tr><td>&#160;</td><td>int <var class="pdparam">isoc</var>, </td></tr><tr><td>&#160;</td><td>int <var class="pdparam">bytecount</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer">&#160;</div></div></div><div class="refsect1"><a name="idp1116714948"></a><h2>Arguments</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="parameter"><code>speed</code></em></span></dt><dd><p>
4     from dev-&gt;speed; USB_SPEED_{LOW,FULL,HIGH}
5    </p></dd><dt><span class="term"><em class="parameter"><code>is_input</code></em></span></dt><dd><p>
6     true iff the transaction sends data to the host
7    </p></dd><dt><span class="term"><em class="parameter"><code>isoc</code></em></span></dt><dd><p>
8     true for isochronous transactions, false for interrupt ones
9    </p></dd><dt><span class="term"><em class="parameter"><code>bytecount</code></em></span></dt><dd><p>
10     how many bytes in the transaction.
11    </p></dd></dl></div></div><div class="refsect1"><a name="idp1116719828"></a><h2>Return</h2><p>
12   Approximate bus time in nanoseconds for a periodic transaction.
13</p></div><div class="refsect1"><a name="idp1116720500"></a><h2>Note</h2><p>
14   See USB 2.0 spec section 5.11.3; only periodic transfers need to be
15   scheduled in software, this function is only used for such scheduling.
16</p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="hcd.html">Prev</a>&#160;</td><td width="20%" align="center"><a accesskey="u" href="hcd.html">Up</a></td><td width="40%" align="right">&#160;<a accesskey="n" href="API-usb-hcd-link-urb-to-ep.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter&#160;6.&#160;Host Controller APIs&#160;</td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top">&#160;<span class="phrase">usb_hcd_link_urb_to_ep</span></td></tr></table></div></body></html>
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