33 lines
1.4 KiB
Plaintext
33 lines
1.4 KiB
Plaintext
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This project provides a build framework for TomsFastMath on Android.
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Notes / TODO:
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To use the faster ARM inline assembly, TFM_ARM must be defined at compile time. Unfortunately, is
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incompatible with the armeabi build target because some of the instructions are not supported. The
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Android SDK defines a few variables which may help with detection:
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when compiled for armeabi-v7a:
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__thumb2__
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__ARM_ARCH_7A__
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when compiled for armeabi:
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__SOFTFP__
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For now, the armeabi target will use the unoptimized C code. TFM_ARM is conditionally defined
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for the armeabi-v7a target.
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Build instructions:
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(1) Clone this git repository to your project's JNI directory, naming the directory "tfm".
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(2) Modify your JNI root's Android.mk and Application.mk using the files in this directory as a model.
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(3) Run ndk-build (available from the Android NDK); see Gingerbread's NDK docs for more.
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Known bugs / issues:
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* armeabi builds are known to produce binary code that is over three times larger than armeabi-v7a.
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This is probably due to either a bug in the Android NDK or limitations of the Thumb16 instruction set.
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* NEON support can't really be turned on, because not all armeabi-v7a boards support it.
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After some trials, it appears that gcc can auto-vectorize some loops when NEON support is enabled
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and this leads to a performance increase. But doing so will cause the code to crash on phones
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where NEON isn't supported...
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