page.title=Configuring a Shared Library
@jd:body

<!--
    Copyright 2016 The Android Open Source Project

    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at

        http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
-->

<p>After creating an
<a href="{@docRoot}devices/audio/implement-policy.html">audio policy
configuration</a>, you must package the HAL implementation into a shared library
and copy it to the appropriate location:</p>

<ol>
<li>Create a <code>device/&lt;company&gt;/&lt;device&gt;/audio</code>
directory to contain your library's source files.</li>
<li>Create an <code>Android.mk</code> file to build the shared library. Ensure
the Makefile contains the following line:
<br>
<pre>
LOCAL_MODULE := audio.primary.&lt;device&gt;
</pre>
<br>
<p>Your library must be named <code>audio.primary.&lt;device&gt;.so</code>
so Android can correctly load the library. The <code>primary</code> portion of
this filename indicates that this shared library is for the primary audio
hardware located on the device. The module names
<code>audio.a2dp.&lt;device&gt;</code> and
<code>audio.usb.&lt;device&gt;</code> are also available for Bluetooth and
USB audio interfaces. Here is an example of an <code>Android.mk</code> from the
Galaxy Nexus audio hardware:</p>
<p><pre>
LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_MODULE := audio.primary.tuna
LOCAL_MODULE_RELATIVE_PATH := hw
LOCAL_SRC_FILES := audio_hw.c ril_interface.c
LOCAL_C_INCLUDES += \
        external/tinyalsa/include \
        $(call include-path-for, audio-utils) \
        $(call include-path-for, audio-effects)
LOCAL_SHARED_LIBRARIES := liblog libcutils libtinyalsa libaudioutils libdl
LOCAL_MODULE_TAGS := optional

include $(BUILD_SHARED_LIBRARY)
</pre></p>
</li>
<br>
<li>If your product supports low latency audio as specified by the Android CDD,
copy the corresponding XML feature file into your product. For example, in your
product's <code>device/&lt;company&gt;/&lt;device&gt;/device.mk</code>
Makefile:
<p><pre>
PRODUCT_COPY_FILES := ...

PRODUCT_COPY_FILES += \
frameworks/native/data/etc/android.hardware.audio.low_latency.xml:system/etc/permissions/android.hardware.audio.low_latency.xml \
</pre></p>
</li>
<br>
<li>Copy the audio policy configuration file you created earlier to the
<code>system/etc/</code> directory in your product's
<code>device/&lt;company&gt;/&lt;device&gt;/device.mk</code> Makefile.
For example:
<p><pre>
PRODUCT_COPY_FILES += \
        device/samsung/tuna/audio/audio_policy.conf:system/etc/audio_policy.conf
</pre></p>
</li>
<br>
<li>Declare the shared modules of your audio HAL that are required by your
product in the product's
<code>device/&lt;company&gt;/&lt;device&gt;/device.mk</code> Makefile.
For example, the Galaxy Nexus requires the primary and Bluetooth audio HAL
modules:
<pre>
PRODUCT_PACKAGES += \
        audio.primary.tuna \
        audio.a2dp.default
</pre>
</li>
</ol>