Clean up some errors from textproc/igor
by wrapping long lines. Event: vBSDcon Hackathon
This commit is contained in:
Benedict Reuschling
parent
999f8925ae
commit
743c61d608
Notes:
svn2git
2020-12-08 03:00:23 +00:00
svn path=/head/; revision=53370
1 changed files with 47 additions and 30 deletions
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@ -4,15 +4,22 @@
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$FreeBSD$
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-->
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<chapter xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" version="5.0" xml:id="oss">
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<info><title>Sound Subsystem</title>
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<authorgroup>
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<author><personname><firstname>Jean-Francois</firstname><surname>Dockes</surname></personname><contrib>Contributed by </contrib></author>
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</authorgroup>
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</info>
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<chapter xmlns="http://docbook.org/ns/docbook"
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xmlns:xlink="http://www.w3.org/1999/xlink" version="5.0"
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xml:id="oss">
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<info>
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<title>Sound Subsystem</title>
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<authorgroup>
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<author>
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<personname>
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<firstname>Jean-Francois</firstname>
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<surname>Dockes</surname>
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</personname>
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<contrib>Contributed by </contrib>
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</author>
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</authorgroup>
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</info>
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<sect1 xml:id="oss-intro">
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<title>Introduction</title>
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@ -96,7 +103,9 @@
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<title>Probing, Attaching, etc.</title>
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<para>Sound drivers probe and attach in almost the same way as any
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hardware driver module. You might want to look at the <link linkend="isa-driver"> ISA</link> or <link linkend="pci">PCI</link> specific sections of the handbook for
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hardware driver module. You might want to look at the <link
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linkend="isa-driver">ISA</link> or <link
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linkend="pci">PCI</link> specific sections of the handbook for
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more information.</para>
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<para>However, sound drivers differ in some ways:</para>
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@ -104,9 +113,9 @@
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<itemizedlist>
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<listitem>
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<para>They declare themselves as <filename>pcm</filename>
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class devices, with a
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<varname remap="structname">struct snddev_info</varname> device private
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structure:</para>
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class devices, with a <varname
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remap="structname">struct snddev_info</varname> device
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private structure:</para>
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<programlisting> static driver_t xxx_driver = {
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"pcm",
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@ -117,8 +126,11 @@
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DRIVER_MODULE(snd_xxxpci, pci, xxx_driver, pcm_devclass, 0, 0);
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MODULE_DEPEND(snd_xxxpci, snd_pcm, PCM_MINVER, PCM_PREFVER,PCM_MAXVER);</programlisting>
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<para>Most sound drivers<indexterm><primary>device
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drivers</primary><secondary>sound</secondary></indexterm>
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<para>Most sound drivers
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<indexterm>
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<primary>device drivers</primary>
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<secondary>sound</secondary>
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</indexterm>
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need to store additional private information about their
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device. A private data structure is usually allocated in
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the attach routine. Its address is passed to
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@ -134,7 +146,8 @@
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<para>The sound driver attach routine should declare its MIXER
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or AC97 interface to <filename>pcm</filename> by calling
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<function>mixer_init()</function>. For a MIXER interface,
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this causes in turn a call to <link linkend="xxxmixer-init"><function>xxxmixer_init()</function></link>.</para>
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this causes in turn a call to <link
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linkend="xxxmixer-init"><function>xxxmixer_init()</function></link>.</para>
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</listitem>
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<listitem>
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@ -196,7 +209,8 @@
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<title>Interfaces</title>
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<para>The interface between the <filename>pcm</filename> core
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and the sound drivers is defined in terms of <link linkend="kernel-objects">kernel objects</link>.</para>
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and the sound drivers is defined in terms of <link
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linkend="kernel-objects">kernel objects</link>.</para>
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<para>There are two main interfaces that a sound driver will
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usually provide: <emphasis>CHANNEL</emphasis> and either
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@ -235,11 +249,12 @@
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<para>For sound data transfers, the
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<filename>pcm</filename> core and the sound drivers
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communicate through a shared memory area, described by a
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<varname remap="structname">struct snd_dbuf</varname>.</para>
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<varname remap="structname">struct
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snd_dbuf</varname>.</para>
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<para><varname remap="structname">struct snd_dbuf</varname> is private to
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<filename>pcm</filename>, and sound drivers obtain
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values of interest by calls to accessor functions
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<para><varname remap="structname">struct snd_dbuf</varname> is
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private to <filename>pcm</filename>, and sound drivers
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obtain values of interest by calls to accessor functions
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(<function>sndbuf_getxxx()</function>).</para>
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<para>The shared memory area has a size of
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@ -253,7 +268,8 @@
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<itemizedlist>
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<listitem>
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<para><filename>pcm</filename> initially fills up the
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buffer, then calls the sound driver's <link linkend="channel-trigger">
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buffer, then calls the sound driver's <link
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linkend="channel-trigger">
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<function>xxxchannel_trigger()</function></link>
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function with a parameter of PCMTRIG_START.</para>
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</listitem>
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@ -273,8 +289,9 @@
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<listitem>
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<para><function>chn_intr()</function> arranges to copy new
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data to the area that was transferred to the device (now
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free), and make appropriate updates to the
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<varname remap="structname">snd_dbuf</varname> structure.</para>
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free), and make appropriate updates to the <varname
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remap="structname">snd_dbuf</varname>
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structure.</para>
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</listitem>
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</itemizedlist>
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</sect3>
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@ -301,8 +318,8 @@
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<calloutlist>
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<callout arearefs="co-chinit-params">
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<para><varname>b</varname> is the address for the channel
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<varname remap="structname">struct snd_dbuf</varname>. It should be
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initialized in the function by calling
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<varname remap="structname">struct snd_dbuf</varname>.
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It should be initialized in the function by calling
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<function>sndbuf_alloc()</function>. The buffer size to
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use is normally a small multiple of the 'typical' unit
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transfer size for your device.</para>
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@ -491,10 +508,10 @@
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<callout arearefs="co-chgetcaps-return">
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<para>The routine returns a pointer to a (usually
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statically-defined)
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<varname remap="structname">pcmchan_caps</varname> structure (defined
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in <filename>sound/pcm/channel.h</filename>. The
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structure holds the minimum and maximum sampling
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statically-defined) <varname
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remap="structname">pcmchan_caps</varname> structure
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(defined in <filename>sound/pcm/channel.h</filename>.
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The structure holds the minimum and maximum sampling
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frequencies, and the accepted sound formats. Look at
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any sound driver for an example.</para>
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</callout>
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@ -626,7 +643,7 @@
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<para><function>xxxmixer_uninit()</function> should ensure
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that all sound is muted and if possible mixer hardware
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should be powered down </para>
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should be powered down.</para>
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<para><function>xxxmixer_reinit()</function> should ensure
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that the mixer hardware is powered up and any settings not
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