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设计师网站家装,网站建设外文版要求,科技网站设计公司排行榜,网站建设需要哪些技能目录一、代码编写二、编译系统配置实现 Hal 模块 一、代码编写 接下来就来为上节实现的驱动写一个简单的 HAL 模块。 在 hardware/libhardware/include/hardware 目录下添加 hello_hal.h#xff1a; #ifndef _HARDWARE_HELLO_HAL_H #define _HARDWARE_HELLO_HAL_H#inclu…目录一、代码编写二、编译系统配置实现 Hal 模块一、代码编写接下来就来为上节实现的驱动写一个简单的 HAL 模块。在hardware/libhardware/include/hardware目录下添加hello_hal.h#ifndef_HARDWARE_HELLO_HAL_H#define_HARDWARE_HELLO_HAL_H#includehardware/hardware.h__BEGIN_DECLS#defineHELLO_HAL_API_VERSIONHARDWARE_MODULE_API_VERSION(1,0)#defineHELLO_HAL_HARDWARE_MODULE_IDhello_hal#defineHELLO_HAL_DEVICE_ID_MAINmain_hello_halstructhello_hal_device_t;typedefstructhello_hal_device_t{structhw_device_tcommon;intfd;// 存储/dev/hello的文件描int(*hello_hal_open)(structhello_hal_device_t*hello_hal_dev);int(*hello_hal_read)(structhello_hal_device_t*hello_hal_dev,char*str);int(*hello_hal_write)(structhello_hal_device_t*hello_hal_dev,constchar*str);}hello_hal_device_t;staticinlineinthello_hal_methods_open(conststructhw_module_t*module,hello_hal_device_t**device){returnmodule-methods-open(module,HELLO_HAL_DEVICE_ID_MAIN,(structhw_device_t**)device);}__END_DECLS#endif// _HARDWARE_HELLO_HAL_H这里的核心是实现一个hello_hal_device_t结构体这个结构体用于操作具体的硬件实现hello_hal_methods_open函数这个函数用于从hw_module_t中找到hello_hal_device_t结构体实例接着在hardware/libhardware/modules/目录下添加hello_hal目录并在hello_hal目录下添加源码文件hello_hal.c#includehardware/hello_hal.h#includehardware/hardware.h#includecutils/log.h#includemalloc.h#includestdio.h#includeunistd.h#includefcntl.h#includeerrno.h#includestring.hinthello_open(structhello_hal_device_t*hello_hal_dev __unused){// 打开/dev/hellofd存入设备结构体hello_hal_dev-fdopen(/dev/hello,O_RDWR);if(hello_hal_dev-fd-1){ALOGE(hello_hal: can not open file /dev/hello, errno%d,errno);// 用ALOGE打印日志return-1;}return0;}inthello_close(structhw_device_t*dev){hello_hal_device_t*hello_hal_dev(hello_hal_device_t*)dev;if(hello_hal_dev-fd0){close(hello_hal_dev-fd);// 关闭结构体中的fd}free(hello_hal_dev);// 释放设备结构体内存return0;}inthello_read(structhello_hal_device_t*hello_hal_dev __unused,char*str){charbuf[1024]{0};// 初始化缓冲区避免脏数据intlenread(hello_hal_dev-fd,buf,sizeof(buf)-1);if(len0){buf[len]\0;strcpy(str,buf);returnlen;}elseif(len0){ALOGW(hello_hal: read 0 bytes from /dev/hello);return0;}else{ALOGE(hello_hal: read failed, errno%d,errno);return-1;}}inthello_write(structhello_hal_device_t*hello_hal_dev __unused,constchar*str){if(!str){// 空指针校验ALOGE(hello_hal: write str is NULL);return-EINVAL;}intlenstrlen(str)1;lenlen1024?len:1024;intretwrite(hello_hal_dev-fd,str,len);if(ret0){ALOGE(hello_hal: write failed, errno%d,errno);return-1;}returnret;}// HAL模块的open函数创建设备实例staticinthello_hal_open(consthw_module_t*module,constchar*id __unused,hw_device_t**device){// 分配设备结构体内存calloc自动初始化0hello_hal_device_t*hello_hal_devcalloc(1,sizeof(hello_hal_device_t));if(!hello_hal_dev){ALOGE(hello_hal: Can not allocate memory for hello hal device);return-ENOMEM;}// 初始化hw_device_tHAL框架要求hello_hal_dev-common.tagHARDWARE_DEVICE_TAG;hello_hal_dev-common.module(hw_module_t*)module;hello_hal_dev-common.versionHARDWARE_DEVICE_API_VERSION(1,0);hello_hal_dev-common.closehello_close;// 现在类型匹配// 绑定自定义函数指针hello_hal_dev-hello_hal_openhello_open;hello_hal_dev-hello_hal_writehello_write;hello_hal_dev-hello_hal_readhello_read;// 输出设备指针给上层*device(hw_device_t*)hello_hal_dev;return0;}// HAL模块方法结构体staticstructhw_module_methods_thello_hal_module_methods{.openhello_hal_open,};// HAL模块入口必须命名为HAL_MODULE_INFO_SYMstructhw_module_tHAL_MODULE_INFO_SYM{.tagHARDWARE_MODULE_TAG,.module_api_versionHELLO_HAL_API_VERSION,.hal_api_versionHARDWARE_HAL_API_VERSION,.idHELLO_HAL_HARDWARE_MODULE_ID,.nameDefault Hello HAL,.authorsixian,.methodshello_hal_module_methods,};声明一个hw_module_t结构体实例声明一个hw_module_methods_t结构体实例其中open函数指针指向hello_hal_openhello_hal_open 会构建一个hello_hal_device_t结构体实例对其成员赋值核心的成员主要是hello_hal_open 、hello_hal_write、 hello_hal_read三个函数指针二、编译系统配置接着在hardware/libhardware/modules/hello_hal目录下添加 Android.mkLOCAL_PATH:$(call my-dir)include $(CLEAR_VARS)LOCAL_MODULE:hello_hal.default#HAL module implementation stored in#hw/VIBRATOR_HARDWARE_MODULE_ID.default.soLOCAL_MODULE_RELATIVE_PATH:hw LOCAL_C_INCLUDES:hardware/libhardware LOCAL_SRC_FILES:hello_hal.c LOCAL_SHARED_LIBRARIES:liblog LOCAL_MODULE_TAGS:optional include $(BUILD_SHARED_LIBRARY)接着在hardware/libhardware/modules/Android.mk中添加hello_hal这样编译系统才会去编译hello_hal模块。hardware_modules:\ camera \ gralloc \ sensors \ hello_hal include $(call all-named-subdir-makefiles,$(hardware_modules))接着在 product 配置文件device/xxxx/xxxx/device.mk中添加hello_hal.defaultso库PRODUCT_PACKAGES:\ audio.primary.goldfish \ vibrator.goldfish \ hello_hal.default\至此hal 层任务完工