Android NDK中编译Openblas库

1、下载安装并配置NDK环境

如已有该环境，跳过。

国内推荐在此下载：

http://www.androiddevtools.cn/

我用的是android-ndk-r14b-linux-x86_64.zip。

2、下载OpenBLAS并解压

https://github.com/xianyi/OpenBLAS

编译可参看

https://github.com/xianyi/OpenBLAS/wiki/How-to-build-OpenBLAS-for-Android

我用的是OpenBLAS-0.2.20

3、编译Openblas

1)打开终端设置环境变量：

export PATH=/home/xx/android-ndk-r14b/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/bin:$PATH

2)修正ndk路径

在以下文件中

OpenBLAS-0.2.20/interface/Makefile

OpenBLAS-0.2.20/driver/level2/Makefile

OpenBLAS-0.2.20/driver/level3/Makefile

OpenBLAS-0.2.20/driver/others/Makefile

OpenBLAS-0.2.20/kernel/Makefile

加入：

override CFLAGS += -I/home/xx/android-ndk-r14b/platforms/android-19/arch-arm/usr/include -I.

3)此时编译的话会遇到以下错误

/home/xx/android-ndk-r14b/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin/ld: error: cannot open crtbegin_so.o: 没有那个文件或目录

/home/xx/android-ndk-r14b/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin/ld: error: cannot open crtend_so.o: 没有那个文件或目录

/home/xx/android-ndk-r14b/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin/ld: error: cannot open crtbegin_so.o: 没有那个文件或目录

/home/xx/android-ndk-r14b/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin/ld: error: cannot open crtend_so.o: 没有那个文件或目录

collect2: error: ld returned 1 exit status

Makefile:140: recipe for target '../libopenblas_armv7p-r0.2.20.so' failed

make[1]: *** [../libopenblas_armv7p-r0.2.20.so] Error 1

make[1]: Leaving directory '/home/acrfid/can/OpenBLAS-0.2.20/exports'

Makefile:90: recipe for target 'shared' failed

make: *** [shared] Error 2

解决方式：

进入OpenBLAS-0.2.20/exports目录，输入以下指令：

ln -snf /home/xx/android-ndk-r14b/platforms/android-19/arch-arm/usr/lib/crtbegin_so.o ./

ln -snf /home/xx/android-ndk-r14b/platforms/android-19/arch-arm/usr/lib/crtend_so.o ./

ln -snf /home/xx/android-ndk-r14b/platforms/android-19/arch-arm/usr/lib/crtbegin_dynamic.o ./

ln -snf /homexx/android-ndk-r14b/platforms/android-19/arch-arm/usr/lib/crtend_android.o ./

4）编译

进入OpenBLAS-0.2.20目录，输入以下指令：

make TARGET=ARMV7 ARM_SOFTFP_ABI=1 HOSTCC=gcc CC=arm-linux-androideabi-gcc NOFORTRAN=1

成功后：

OpenBLAS build complete. (BLAS CBLAS)

OS ... Android

Architecture ... arm

BINARY ... 32bit

C compiler ... GCC (command line : arm-linux-androideabi-gcc)

Library Name ... libopenblas_armv7p-r0.2.20.a (Multi threaded; Max num-threads is 4)

To install the library, you can run "make PREFIX=/path/to/your/installation install".

安装

make PREFIX=/home/xx/OpenBLAS-0.2.20/install install