43809914f6
It is provided as a static library that NDK developers can link against. The code is designed to run on all official Android platforms, starting from Android 1.5.
93 lines
2.9 KiB
Plaintext
93 lines
2.9 KiB
Plaintext
Android NDK CPU Features detection library:
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This NDK provides a small library named "cpufeatures" that can be used at
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runtime to detect the target device's CPU family and the optional features
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it supports.
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Usage:
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------
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The library is available from sources/cpufeatures. It provides an Android.mk
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build script that can be used to build it as a static library.
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To use it, you must:
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* add 'cpufeatures' to your APP_MODULES list in your Application.mk
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* include 'sources/cpufeatures/Android.mk' at the start or end of your
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Android.mk file.
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* add 'sources/cpufeatures' to your LOCAL_C_INCLUDES definition.
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* add 'cpufeatures' to your LOCAL_STATIC_LIBRARIES definition when building
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your final shared library.
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your source code can then #include <cpu-features.h> to compile against it.
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Here is a simple example:
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<NDK>/apps/<appname>/Application.mk:
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APP_PROJECT_PATH := <project-path>
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APP_MODULES := <your-modules> cpufeatures
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<project-path>/jni/Android.mk:
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LOCAL_PATH := $(call my-dir)
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include $(CLEAR_VARS)
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LOCAL_MODULE := <your-module-name>
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LOCAL_C_INCLUDES += sources/cpufeatures
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LOCAL_SRC_FILES := <your-source-files>
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LOCAL_STATIC_LIBRARIES += cpufeatures
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include $(BUILD_SHARED_LIBRARY)
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include sources/cpufeature/Android.mk
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Features:
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---------
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Two functions are provided for now:
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AndroidCpuFamily android_getCpuFamily();
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Returns the target device's CPU Family as an enum. For now, the only
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supported family is ANDROID_CPU_FAMILY_ARM.
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uint64_t android_getCpuFeatures();
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Returns the set of optional features supported by the device's CPU.
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The result is a set of bit-flags, each corresponding to one CPU
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Family-specific optional feature.
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Currently, only the following flags are defined, for the ARM CPU Family:
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ANDROID_CPU_ARM_FEATURE_ARMv7
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Indicates that the device's CPU supports the ARMv7-A instruction
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set as supported by the "armeabi-v7a" abi (see CPU-ARCH-ABIS.TXT).
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This corresponds to Thumb-2 and VFPv3-D16 instructions.
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ANDROID_CPU_ARM_FEATURE_VFPv3
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Indicates that the device's CPU supports the VFPv3 hardware FPU
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instruction set extension. Due to the definition of 'armeabi-v7a',
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this will always be the case if ANDROID_CPU_ARM_FEATURE_ARMv7 is
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returned.
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Note that this corresponds to the minimum profile VFPv3-D16 that
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only provides 16 hardware FP registers.
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ANDROID_CPU_ARM_FEATURE_NEON
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Indicates that the device's CPU supports the ARM Advanced SIMD
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(a.k.a. NEON) vector instruction set extension. Note that ARM
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mandates that such CPUs also implement VFPv3-D32, which provides
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32 hardware FP registers (shared with the NEON unit).
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Important Note:
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---------------
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The cpufeatures library will be updated to support more CPU families and
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optional features in the future. It is designed to work as-is on all
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official Android platform versions.
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