使用NDK对静态库中的函数进行未定义的引用

Question

所以我试图在我的本机代码上使用libopus来安装Android应用程序.我的Android.mk文件如下所示:

PLATFORM_PREFIX := /opt/android-ext/
LOCAL_PATH := $(PLATFORM_PREFIX)/lib

include $(CLEAR_VARS)

LOCAL_MODULE := libopus
LOCAL_SRC_FILES := libopus.a

include $(PREBUILT_STATIC_LIBRARY)

# I have to redeclare LOCAL_PATH because the library is in /opt/android-ext/
# and my project is somewhere else. Not very elegant.

LOCAL_PATH := /home/sergio/workspace/Project/jni

include $(CLEAR_VARS)

LOCAL_MODULE := opusUtilsNative
LOCAL_SRC_FILES := opusUtilsNative.c
LOCAL_C_INCLUDES += $(PLATFORM_PREFIX)/include
LOCAL_STATIC_LIBRARIES := android_native_app_glue libopus

include $(BUILD_SHARED_LIBRARY)

我在opusUtilsNative.c中的代码如下所示:

#include "opusUtilsNative.h"
#include <opus/opus.h>
#include <opus/opus_types.h>

JNIEXPORT jbyteArray JNICALL Java_Project_OpusUtils_encode
  (JNIEnv * je, jclass jc, jbyteArray data){

    int rc;
    opus_int16 * testOutBuffer;
    unsigned char* opusBuffer;

    OpusDecoder *dec;

    dec = opus_decoder_create(48000, 2, &rc);
    return data;
}

当我尝试构建它时,只有当我删除使用"opus_decoder_create"函数的行时它才能正常工作.否则我会得到这个:

error: undefined reference to 'opus_decoder_create'

我可以看到opus_decoder_create在opus.h上明确定义,显然是包含在内,因为如果我排除该行,我将得到关于opus_int16和OpusDecoder声明的错误.为什么要包含一些定义而有些定义不包括在内？

任何帮助将不胜感激.

Answer 1

这很棘手.经过一段时间的挖掘后,我意识到我没有正确地交叉编译opus库,毕竟我没有ARM二进制文件.

验证库是否正确交叉编译的好方法:

cd /opt/android-ext/lib #Or wherever the .a file is
ar x libopus.a
file tables_LTP.o #Or any of the .o files generated by ar x

输出应如下所示:

tables_LTP.o: ELF 32-bit LSB relocatable, ARM, version 1 (SYSV), not stripped

否则,您可能需要仔细检查交叉编译过程.