在android中如何编译连接 .c 的可执行文件

最新推荐文章于 2024-12-07 12:31:18 发布

pillarbuaa

最新推荐文章于 2024-12-07 12:31:18 发布

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分类专栏： Andorid 分析-make

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本文介绍如何在Android环境中搭建简单的测试应用，包括创建项目、编写测试代码、编译及运行等步骤。通过示例展示了如何读取电池容量，并控制显示模式。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

1. 在./development目录下创建一目录如：myhello
2. 进入hello目录，在其下编写自己的.c文件,如: myhello.c
   #include <stdio.h>
   int main()
   {
       printf("hello world\n");
       exit(0);
       //return 0;
   }
3. 在hello目录中，编写Android.mk, 内容如下：
   LOCAL_PATH:= $(call my-dir)
   include $(CLEAR_VARS)
   LOCAL_MODULE := myhelloworld
   LOCAL_SRC_FILES := myhello.c
   LOCAL_MODULE_TAGS := optional
   include $(BUILD_EXECUTABLE)
4. 回到Android源代码顶层目录，进行编译，make myhelloworld
5. 生成的可执行文件位于:out/target/product/lotus/system/bin/ 目录下
6. adb push 到手机 /data 目录下,然后进入adb shell,到data目录下,执行./myhelloworld 皆可

手动编译连接【arm-eabi-gcc 的目录随andorid的版本而有变化，还有就是需要链接的文件如果比较多时，需要很多-l 就很麻烦了】
7、编译成目标文件：
   #$(yourAndroid)/prebuilt/linux-x86/toolchain/[arm-eabi-4.2.1]/bin/arm-eabi-gcc -I bionic/libc/arch-arm/include/ -I bionic/libc/include -I bionic/libc/kernel/common -I bionic/libc/kernel/arch-arm -g -c helloworld.c -o hello.o
8、生成可执行代码：
   #$(yourAndroid)/prebuilt/linux-x86/toolchain/[arm-eabi-4.2.1]/bin/arm-eabi-gcc -nostdlib -Bdynamic -Wl,-T,build/core/armelf.x -Wl,-dynamic-linker,/system/bin/linker -Wl,--gc-sections -Wl,-z,nocopyreloc -o helloworld -Lout/target/product/[generic]/obj/lib -Wl,-rpath-link=out/target/product/[generic]/obj/lib -lc hello.o -entry=main

其中[ ]中部分根据实际情况修改

**************************************************

实验：

1. 建目录(my android)/development/test，在该目录下新建 Android.mk和fb_test.c文件

2. Android.mk文件

LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := myfbtest
LOCAL_SRC_FILES := fb_test.c
LOCAL_MODULE_TAGS := optional
include $(BUILD_EXECUTABLE)

3. 以下为fb_test.c
#include <fcntl.h>
#include <linux/fb.h>
#include <sys/mman.h>
#include <linux/kd.h>

#include <stdio.h>

#define FBBIT_PER_PIXEL 32
#define FBBIT_PIXEL_IMAGE 16
#define PIXELS_WIDTH_BYTE 4
#define BYTE_PER_PIXEL 3
#define FB_GRAPHICS_PATH "/dev/graphics/fb0"
#define DEV_TTY0_PATH "/dev/tty0"

#define DISPLAY_ERROR -1
#define DISPLAY_SUCCESS 0

#define GET_BATTERYCAPACITY_ERR -1

#define MAX_STR 255

static struct {
   int fd;
   void *pixels;
   struct fb_fix_screeninfo fixed;
   struct fb_var_screeninfo var;
   int align_xres;
} fb;

int getBatteryCapacity(void)
{
   FILE *in;
   char tmpStr[MAX_STR + 1];
   char capfile[] = "/sys/class/power_supply/battery/capacity";

   if (capfile == NULL)
       return GET_BATTERYCAPACITY_ERR;

   in = fopen(capfile, "rt");
   if (in == NULL)
       return GET_BATTERYCAPACITY_ERR;

   if (fgets(tmpStr, MAX_STR, in) == NULL) {
       printf("Failed to read battery capacity!\n");
       fclose(in);
       return GET_BATTERYCAPACITY_ERR;

   }

   printf("Battery capacity(ascii): %s\n", tmpStr);
   fclose(in);

   return 0;//atoi(tmpStr);
}

static int vt_set_graphicsmode(int graphics)
{
   int fd, r;
   fd = open(DEV_TTY0_PATH, O_RDWR | O_SYNC);
   if (fd < 0)
       return DISPLAY_ERROR;
   r = ioctl(fd, KDSETMODE, graphics);
   close(fd);
   return r;
}

int display_init(void)
{
   fb.fd = open(FB_GRAPHICS_PATH, O_RDWR);
   if (fb.fd < 0)
       return DISPLAY_ERROR;

   if (ioctl(fb.fd, FBIOGET_FSCREENINFO, &fb.fixed) < 0)
       return DISPLAY_ERROR;
   if (ioctl(fb.fd, FBIOGET_VSCREENINFO, &fb.var) < 0)
       return DISPLAY_ERROR;
   fb.align_xres = fb.fixed.line_length /
       (fb.var.bits_per_pixel >> BYTE_PER_PIXEL);

   fb.pixels = mmap(0, fb.fixed.line_length * fb.var.yres_virtual,
       PROT_READ | PROT_WRITE, MAP_SHARED, fb.fd, 0);
   if (fb.pixels == MAP_FAILED)
       return DISPLAY_ERROR;

   vt_set_graphicsmode(KD_GRAPHICS);

   memset(fb.pixels, 0, fb.fixed.line_length * fb.var.yres_virtual);
   //display_update(fb.pixels, fb.align_xres, fb.var.yres);
   fb.var.activate = FB_ACTIVATE_FORCE;
   ioctl(fb.fd, FBIOPUT_VSCREENINFO, &fb.var);

   printf("display_init ok\n");

   return DISPLAY_SUCCESS;
}

void display_on(void)
{
   ioctl(fb.fd, FBIOBLANK, FB_BLANK_UNBLANK);
}

void display_off(void)
{
   ioctl(fb.fd, FBIOBLANK, FB_BLANK_POWERDOWN);
}

int main()
{
   display_init();
   display_off();//关显示屏

   getBatteryCapacity();
   sleep(5);

   display_on();//开显示屏

   return 0;
}