我们在调试Android系统代码的时候，出于学习/debug的目的，经常需要加ALOG来输出LOG。因为print函数是输出到terminal终端的，系统在运行的时候并没有这样的终端，所以需要用Android的LOG系统，也就是ALOG来输出我们想获得的debug信息。有些模块是从Linux移植过来的，往往打印LOG的时候，原本的实现要依赖于vsnprint或者vscprint这样的函数，而这类函数是在Android中不工作的，此时我们就需要将原来的LOG实现进行改写
分两种情况：
情况1: 在Android的Source Code里编译，也就是In Code Tree编译
首先需要在.mk文件中include进 system/core/include，然后引用#include <cutils/log.h>之后，就可以直接使用ALOG函数了。这里的system/code/include就是指Android Source Tree中的相对路径，里面包含了lib log等库，其中就有ALOG的定义以及实现
diff --git a/Android.mk b/Android.mk index 4ef0868..49ce951 100644 --- a/Android.mk +++ b/Android.mk LOCAL_CPPFLAGS = \ -fexceptions \ @@ -104,7 +105,8 @@ LOCAL_C_INCLUDES = \ $(LOCAL_PATH)/Source/inc \ $(LOCAL_PATH)/Source/inc/common \ $(LOCAL_PATH)/Source/inc/umKmInc \ - $(LOCAL_PATH)/Source/install + $(LOCAL_PATH)/Source/install \ + system/core/include LOCAL_EXPORT_C_INCLUDE_DIRS = \ $(LOCAL_PATH)/Source/GmmLib/inc \ diff --git a/Source/GmmLib/GlobalInfo/GmmInfo.cpp b/Source/GmmLib/GlobalInfo/GmmInfo.cpp index e203855..6cb9dcf 100644 --- a/Source/GmmLib/GlobalInfo/GmmInfo.cpp +++ b/Source/GmmLib/GlobalInfo/GmmInfo.cpp @@ -21,6 +21,7 @@ OTHER DEALINGS IN THE SOFTWARE. ============================================================================*/ #include "Internal/Common/GmmLibInc.h" +#include <cutils/log.h> //=========================================================================== // Global Variable: @@ -438,6 +439,8 @@ GMM_CLIENT ClientType) this->GtSysInfo = *pGtSysInfo; OverrideSkuWa(); + ALOGE("test ALOGE debug in %s", __func__); + GMM_DPF(GFXDBG_NORMAL, "test wrap ALOGE%s-->\n", __FUNCTION__); pGmmGlobalContext->pPlatformInfo = GmmLib::PlatformInfo::Create(Platform, false); diff --git a/Source/GmmLib/inc/External/Common/GmmDebug.h b/Source/GmmLib/inc/External/Common/GmmDebug.h index a299f50..ed40035 100644 --- a/Source/GmmLib/inc/External/Common/GmmDebug.h +++ b/Source/GmmLib/inc/External/Common/GmmDebug.h @@ -31,6 +31,7 @@ OTHER DEALINGS IN THE SOFTWARE. #else #include "GmmCommonExt.h" #include "GmmLog/GmmLog.h" +#include <cutils/log.h> //===================== Debug Message Levels======================== #define GFXDBG_OFF (0x00000000) #define GFXDBG_CRITICAL (0x00000001) @@ -85,6 +86,13 @@ OTHER DEALINGS IN THE SOFTWARE. #define GMM_DBG_BREAK assert(0) #endif +#if defined(__ANDROID__) +#define GMMLibDebugMessage(DebugLevel, message, ...) \ +{ \ + ALOGD(message, ##__VA_ARGS__); \ +} + +#else #define GMMLibDebugMessage(DebugLevel, message, ...) \ { \ if(DebugLevel == GFXDBG_CRITICAL) \ @@ -104,6 +112,7 @@ OTHER DEALINGS IN THE SOFTWARE. GMM_LOG_INFO(message, ##__VA_ARGS__); \ } \ } +#endif #define GMM_LIB_ASSERT(expr) \ { \
情况2: 利用NDK进行out of tree编译，这种情况往往见于Binary/App从Linux porting 到Android(移植)。
由于没有Android Source Code，自然没有办法include进 system/core/include和引用#include <cutils/log.h>，所以没有办法直接使用ALOG函数。这种情况只能用<android/libutils>代替，也就是在CMakeList.txt的target_link_libraries中，加上-landroid，这里的意思是链接的时候把libandroid这个库给链接上。也没有办法直接用ALOG，可以用__android_log_print代替.
需要值得注意的是有时候我们在CMakeList.txt里加了-landroid，却还是找不到__android__log_print，会报error:undefined reference to '__android_log_print'的错误，这是因为我们虽然在连接的时候写了-landroid，但是编译的时候却没有找到这个package，自然也就无法链接上。一般我们需要在target_link_libraries之前加一句find_package(Threads REQUIRED), 并把-landroid写在target_link_libraries里的Threads::Threads之后就可以了。如下代码所示：
--- a/Source/GmmLib/CMakeLists.txt +++ b/Source/GmmLib/CMakeLists.txt @@ -591,7 +591,7 @@ else() set_target_properties(${GMM_LIB_DLL_NAME} PROPERTIES SOVERSION ${GMMLIB_API_MAJOR_VERSION}) set(THREADS_PREFER_PTHREAD_FLAG ON) find_package(Threads REQUIRED) - target_link_libraries(${GMM_LIB_DLL_NAME} Threads::Threads -static-libstdc++ -llog) + target_link_libraries(${GMM_LIB_DLL_NAME} Threads::Threads -static-libstdc++ -llog -landroid) endif() diff --git a/Source/GmmLib/inc/External/Common/GmmDebug.h b/Source/GmmLib/inc/External/Common/GmmDebug.h index 25503254995..8a38d501407 100644 --- a/Source/GmmLib/inc/External/Common/GmmDebug.h +++ b/Source/GmmLib/inc/External/Common/GmmDebug.h @@ -27,6 +27,9 @@ implied warranties, other than those that are expressly stated in the License. #else #include "GmmCommonExt.h" #include "GmmLog/GmmLog.h" +#if defined(__ANDROID__) +#include <android/log.h> +#endif //===================== Debug Message Levels======================== #define GFXDBG_OFF (0x00000000) #define GFXDBG_CRITICAL (0x00000001) @@ -119,6 +122,14 @@ implied warranties, other than those that are expressly stated in the License. #endif // (_DEBUG) //_DEBUG || _RELEASE_INTERNAL #if (_DEBUG || _RELEASE_INTERNAL) +#if defined(__ANDROID__) + #define LOG_TAG "GMMLib" + #define GMMLibDebugMessage(DebugLevel, message, ...) \ + { \ + __android_log_print(ANDROID_LOG_DEBUG, LOG_TAG, message, ##__VA_ARGS__); \ + } + +#else #define GMMLibDebugMessage(DebugLevel, message, ...) \ { \ if(DebugLevel == GFXDBG_CRITICAL) \ @@ -138,6 +149,7 @@ implied warranties, other than those that are expressly stated in the License. GMM_LOG_INFO(message, ##__VA_ARGS__); \ } \ } +#endif //__ANDROID__ #else #define GMMLibDebugMessage(...)