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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968" /><title>struct ff_envelope</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="Linux Device Drivers" /><link rel="up" href="ch08.html" title="Chapter 8. Input Subsystem" /><link rel="prev" href="re695.html" title="struct ff_trigger" /><link rel="next" href="re697.html" title="struct ff_constant_effect" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><span>struct ff_envelope</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="re695.html">Prev</a> </td><th width="60%" align="center">Chapter 8. Input Subsystem</th><td width="20%" align="right"> <a accesskey="n" href="re697.html">Next</a></td></tr></table><hr /></div><div class="refentry" title="struct ff_envelope"><a id="API-struct-ff-envelope"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>struct ff_envelope —
generic force-feedback effect envelope
</p></div><div class="refsynopsisdiv" title="Synopsis"><h2>Synopsis</h2><pre class="programlisting">
struct ff_envelope {
__u16 attack_length;
__u16 attack_level;
__u16 fade_length;
__u16 fade_level;
}; </pre></div><div class="refsect1" title="Members"><a id="id2697243"></a><h2>Members</h2><div class="variablelist"><dl><dt><span class="term">attack_length</span></dt><dd><p>
duration of the attack (ms)
</p></dd><dt><span class="term">attack_level</span></dt><dd><p>
level at the beginning of the attack
</p></dd><dt><span class="term">fade_length</span></dt><dd><p>
duration of fade (ms)
</p></dd><dt><span class="term">fade_level</span></dt><dd><p>
level at the end of fade
</p></dd></dl></div></div><div class="refsect1" title="Description"><a id="id2697300"></a><h2>Description</h2><p>
The <em class="parameter"><code>attack_level</code></em> and <em class="parameter"><code>fade_level</code></em> are absolute values; when applying
envelope force-feedback core will convert to positive/negative
value based on polarity of the default level of the effect.
Valid range for the attack and fade levels is 0x0000 - 0x7fff
</p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="re695.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ch08.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="re697.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span>struct ff_trigger</span> </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> <span>struct ff_constant_effect</span></td></tr></table></div></body></html>
