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Android JNI开发,手工建立MK模板:
Application.mk
APP_ABI := armeabi-v7a
APP_STL := gnustl_static
APP_CPPFLAGS := -frtti -fexceptions -std=c++11
APP_PLATFORM := android-15
Android.mk
LOCAL_PATH := $(call my-dir)
#print message
#$(warning "the value of LOCAL_PATH is $(LOCAL_PATH)")
include $(CLEAR_VARS)
LOCAL_MODULE := native-lib
LOCAL_C_INCLUDES = $(LOCAL_PATH)/3rdparty/include
LOCAL_SRC_FILES := native-lib.cpp #
#3rdparty/src/aaidsys.c
#3rdparty/src/queue.c
#3rdparty/src/video.c
#3rdparty/src/ysqfd.c
#3rdparty/src/yuvproc.c
#LOCAL_CFLAGS := -mfloat-abi=hard -D_NDK_MATH_NO_SOFTFP=1
LOCAL_CPPFLAGS := -s -mfloat-abi=softfp -mfpu=neon -D_NDK_MATH_NO_SOFTFP=1
####include the 3rdparty(method1)####
#LOCAL_LDLIBS += -llog -L$(LOCAL_PATH)/3rdparty/lib/ -lysqfd32
####include the 3rdparty(method2)####
#LOCAL_SHARED_LIBRARIES := ysqfd32
include $(BUILD_SHARED_LIBRARY)
####the 3rdparty####
include $(CLEAR_VARS)
#$(warning "the value of LOCAL_PATH is $(LOCAL_PATH)")
LOCAL_MODULE := ysqfd32
LOCAL_SRC_FILES := 3rdparty/lib/libysqfd32.so
include $(PREBUILT_SHARED_LIBRARY)
本来想用一下,于仕琪博士的人脸检测库,无奈怎么也链接不上库~~~~
D:/Android/android-sdk-windows/ndk-bundle/toolchains/arm-linux-androideabi-4.9/prebuilt/windows-x86_64/lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/binld: error: ../../../../src/main/jniLibs/armeabi-v7a/libysqfd32.so uses VFP register arguments, output does not
网搜所有的答案,都不能解决问题,只好求助NDK社区(https://github.com/android-ndk/ndk/),得到答复:
https://github.com/android-ndk/ndk/issues/552#event-1308445210
Like I said in the other bug, you don't. Android does not use the hard float calling convention. You do not need -mfloat-abi=hard to use floating point instructions. It only affects the calling convention.
虽然得到google人员的肯定回复,但还是有个疑问:NDK编译工具下的hard是干什么用的?
toolchainsarm-linux-androideabi-4.9prebuiltwindows-x86_64libgccarm-linux-androideabi4.9.xarmv7-ahard*
这些库难道不是为了支持hard float?
还是另找出路:arm-linux-gnueabihf 貌似可以解决我的问题,待实践~~~~
找到原因了,Hard VFP是不支持NDK交叉编译工具的,只能使用板载系统工具本地编译,不过这样arm-linux-gnueabihf又有什么用呢???
其实是支持交叉编译的,使用 arm-linux-gnueabihf 编译后的程序里面有
Tag_ABI_VFP_args: VFP registers
普通的交叉编译工具是没有这个的!!!
How to Detect if an ARM ELF Binary is Hard-float (ARMHF) or Soft-float (ARMEL)
https://www.cnx-software.com/2013/04/22/how-to-detect-if-an-arm-elf-binary-is-hard-float-armhf-or-soft-float-armel/
以下是一个小程序:
@echo off
set PATH=F:gcc-linaro-arm-linux-gnueabihf-4.8-2013.10_win32bin;D:Androidandroid-sdk-windowsplatform-tools;%PATH%
echo "mfloat compiling......"
arm-linux-gnueabihf-gcc.exe -v -static mfloat.c -o demo
rem arm-linux-gnueabihf-gcc.exe -v -ffast-math mfloat.c -o demo
pause
rem arm-linux-gnueabihf-readelf.exe -a demo
pause
rem arm-linux-gnueabihf-readelf.exe -a libysqfd32.so
pause
adb push demo /data/local/tmp/
adb shell chmod 777 /data/local/tmp/demo
adb shell ls -l /data/local/tmp/
adb shell /data/local/tmp/demo
pause
mfloat.c
#include <stdio.h>
int main(void)
{
double a,b,c;
a = 23.543;
b = 323.234;
c = b/a;
printf("the 13/2 = %fn", c);
printf("hello world !n");
return 0;
}
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