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<hr><h1>async.c File Reference</h1>Async notification helpers.
<a href="#_details">More...</a>
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<tr><td colspan=2><br><h2>Functions</h2></td></tr>
<tr><td nowrap align=right valign=top>int </td><td valign=bottom><a class="el" href="async_8c.html#a3">snd_async_add_handler</a> (<a class="el" href="group___global.html#a0">snd_async_handler_t</a> **handler, int fd, <a class="el" href="group___global.html#a1">snd_async_callback_t</a> callback, void *private_data)</td></tr>
<tr><td> </td><td><font size=-1><em>Registers an async handler.</em> <a href="#a3"></a><em></em></font><br><br></td></tr>
<tr><td nowrap align=right valign=top>int </td><td valign=bottom><a class="el" href="async_8c.html#a4">snd_async_del_handler</a> (<a class="el" href="group___global.html#a0">snd_async_handler_t</a> *handler)</td></tr>
<tr><td> </td><td><font size=-1><em>Deletes an async handler.</em> <a href="#a4"></a><em></em></font><br><br></td></tr>
<tr><td nowrap align=right valign=top>int </td><td valign=bottom><a class="el" href="async_8c.html#a5">snd_async_handler_get_signo</a> (<a class="el" href="group___global.html#a0">snd_async_handler_t</a> *handler)</td></tr>
<tr><td> </td><td><font size=-1><em>Returns the signal number assigned to an async handler.</em> <a href="#a5"></a><em></em></font><br><br></td></tr>
<tr><td nowrap align=right valign=top>int </td><td valign=bottom><a class="el" href="async_8c.html#a6">snd_async_handler_get_fd</a> (<a class="el" href="group___global.html#a0">snd_async_handler_t</a> *handler)</td></tr>
<tr><td> </td><td><font size=-1><em>Returns the file descriptor assigned to an async handler.</em> <a href="#a6"></a><em></em></font><br><br></td></tr>
<tr><td nowrap align=right valign=top>void * </td><td valign=bottom><a class="el" href="async_8c.html#a7">snd_async_handler_get_callback_private</a> (<a class="el" href="group___global.html#a0">snd_async_handler_t</a> *handler)</td></tr>
<tr><td> </td><td><font size=-1><em>Returns the private data assigned to an async handler.</em> <a href="#a7"></a><em></em></font><br><br></td></tr>
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<hr><a name="_details"></a><h2>Detailed Description</h2>
Async notification helpers.
<p>
<p>
<dl compact><dt><b>Author: </b></dt><dd>
Abramo Bagnara <<a href="mailto:abramo@alsa-project.org">abramo@alsa-project.org</a>> </dl><dl compact><dt><b>Date: </b></dt><dd>
2001</dl><hr><h2>Function Documentation</h2>
<a name="a3" doxytag="async.c::snd_async_add_handler"></a><p>
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<td class="md" nowrap valign="top"> int snd_async_add_handler </td>
<td class="md" valign="top">( </td>
<td class="md" nowrap valign="top"><a class="el" href="group___global.html#a0">snd_async_handler_t</a> ** </td>
<td class="mdname" nowrap> <em>handler</em>, </td>
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<td></td>
<td></td>
<td class="md" nowrap>int </td>
<td class="mdname" nowrap> <em>fd</em>, </td>
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<td></td>
<td></td>
<td class="md" nowrap><a class="el" href="group___global.html#a1">snd_async_callback_t</a> </td>
<td class="mdname" nowrap> <em>callback</em>, </td>
</tr>
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<td></td>
<td></td>
<td class="md" nowrap>void * </td>
<td class="mdname" nowrap> <em>private_data</em></td>
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<td></td>
<td class="md">) </td>
<td class="md" colspan="2"></td>
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Registers an async handler.
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<dl compact><dt><b>Parameters: </b></dt><dd>
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<tr><td valign=top><em>handler</em> </td><td>
The function puts the pointer to the new async handler object at the address specified by <code>handler</code>. </td></tr>
<tr><td valign=top><em>fd</em> </td><td>
The file descriptor to be associated with the callback. </td></tr>
<tr><td valign=top><em>callback</em> </td><td>
The async callback function. </td></tr>
<tr><td valign=top><em>private_data</em> </td><td>
Private data for the async callback function. </td></tr>
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</dl><dl compact><dt><b>Returns: </b></dt><dd>
Zero if successful, otherwise a negative error code.</dl>This function associates the callback function with the given file, and saves this association in a <code><a class="el" href="group___global.html#a0">snd_async_handler_t</a></code> object.
<p>
Whenever the <code>SIGIO</code> signal is raised for the file <code>fd</code>, the callback function will be called with its parameter pointing to the async handler object returned by this function.
<p>
The ALSA <code>sigaction</code> handler for the <code>SIGIO</code> signal automatically multiplexes the notifications to the registered async callbacks. However, the application is responsible for instructing the device driver to generate the <code>SIGIO</code> signal.
<p>
The <code>SIGIO</code> signal may have been replaced with another signal, see <a class="el" href="async_8c.html#a5">snd_async_handler_get_signo</a>.
<p>
When the async handler isn't needed anymore, you must delete it with <a class="el" href="async_8c.html#a4">snd_async_del_handler</a>.
<p>
<dl compact><dt><b>See also: </b></dt><dd>
<a class="el" href="pcm_8c.html#a51">snd_async_add_pcm_handler</a>, <a class="el" href="control_8c.html#a27">snd_async_add_ctl_handler</a> </dl> </td>
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<a name="a4" doxytag="async.c::snd_async_del_handler"></a><p>
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<td class="md" nowrap valign="top"> int snd_async_del_handler </td>
<td class="md" valign="top">( </td>
<td class="md" nowrap valign="top"><a class="el" href="group___global.html#a0">snd_async_handler_t</a> * </td>
<td class="mdname1" valign="top" nowrap> <em>handler</em> </td>
<td class="md" valign="top">) </td>
<td class="md" nowrap></td>
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<p>
Deletes an async handler.
<p>
<dl compact><dt><b>Parameters: </b></dt><dd>
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<tr><td valign=top><em>handler</em> </td><td>
Handle of the async handler to delete. </td></tr>
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</dl><dl compact><dt><b>Returns: </b></dt><dd>
Zero if successful, otherwise a negative error code. </dl> </td>
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<a name="a7" doxytag="async.c::snd_async_handler_get_callback_private"></a><p>
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<td class="md" nowrap valign="top"> void* snd_async_handler_get_callback_private </td>
<td class="md" valign="top">( </td>
<td class="md" nowrap valign="top"><a class="el" href="group___global.html#a0">snd_async_handler_t</a> * </td>
<td class="mdname1" valign="top" nowrap> <em>handler</em> </td>
<td class="md" valign="top">) </td>
<td class="md" nowrap></td>
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<p>
Returns the private data assigned to an async handler.
<p>
<dl compact><dt><b>Parameters: </b></dt><dd>
<table border=0 cellspacing=2 cellpadding=0>
<tr><td valign=top><em>handler</em> </td><td>
Handle to an async handler. </td></tr>
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</dl><dl compact><dt><b>Returns: </b></dt><dd>
The <code>private_data</code> value registered with the async handler. </dl> </td>
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<a name="a6" doxytag="async.c::snd_async_handler_get_fd"></a><p>
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<td class="md" nowrap valign="top"> int snd_async_handler_get_fd </td>
<td class="md" valign="top">( </td>
<td class="md" nowrap valign="top"><a class="el" href="group___global.html#a0">snd_async_handler_t</a> * </td>
<td class="mdname1" valign="top" nowrap> <em>handler</em> </td>
<td class="md" valign="top">) </td>
<td class="md" nowrap></td>
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<p>
Returns the file descriptor assigned to an async handler.
<p>
<dl compact><dt><b>Parameters: </b></dt><dd>
<table border=0 cellspacing=2 cellpadding=0>
<tr><td valign=top><em>handler</em> </td><td>
Handle to an async handler. </td></tr>
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</dl><dl compact><dt><b>Returns: </b></dt><dd>
The file descriptor if successful, otherwise a negative error code. </dl> </td>
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<a name="a5" doxytag="async.c::snd_async_handler_get_signo"></a><p>
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<td class="md" nowrap valign="top"> int snd_async_handler_get_signo </td>
<td class="md" valign="top">( </td>
<td class="md" nowrap valign="top"><a class="el" href="group___global.html#a0">snd_async_handler_t</a> * </td>
<td class="mdname1" valign="top" nowrap> <em>handler</em> </td>
<td class="md" valign="top">) </td>
<td class="md" nowrap></td>
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<p>
Returns the signal number assigned to an async handler.
<p>
<dl compact><dt><b>Parameters: </b></dt><dd>
<table border=0 cellspacing=2 cellpadding=0>
<tr><td valign=top><em>handler</em> </td><td>
Handle to an async handler. </td></tr>
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</dl><dl compact><dt><b>Returns: </b></dt><dd>
The signal number if successful, otherwise a negative error code.</dl>The signal number for async handlers usually is <code>SIGIO</code>, but wizards can redefine it to a realtime signal when compiling the ALSA library. </td>
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