[Android underlying] HAL hardware abstraction Layer written

Two structural bodies related to Hal hw_module_t, hw_device_t

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I. The relationship between JNI and Hal

TIP: A framework of relationships between several app,jni,hal,framework

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It can be seen that JNI mainly uses pmodule and pdevice to get the variables in the HAL to manipulate the HAL layer

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Second, JNI operation Hal

get HAL layer:1, jni gets the module and device object of the HAL layer

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Operation Hal layer :2, JNI operation HAL Layer

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JNI Operation HAL Complete code reference [Android Bottom]jni Get custom class function written to compare

Iii. Writing of Hal

Writing HAL Note points (Notes section)

1, Hal's. h file writing, own hardware custom modules and device writing, led for example 650) this.width=650; "Src=" https://note.wiz.cn/unzip/ 232b0826-d65c-4c92-bde7-64832286df9e/bd291518-ffe1-45de-8ddc-4994486b6e16.1519/index_files/ 55541905-052a-4490-84e2-37770b5dca1a.png "style=" border:0px;font-size:10.5pt;line-height:1.5; "alt=" 55541905-052a-4490-84e2-37770b5dca1a.png "/>

2. Steps for writing the. c File of Hal

Write the two cores of the HAL

structure of a structural body hw_module_t

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An open function in a hw_module_methods_t;

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Hal Authoring Steps

First step:hal everything starts with the HMI

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Step Two:

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Step three: Implement the function of JNI acquisition device (hw_device_t) Operation

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Iv. functions that implement the release (free) device (hw_device_t) of the JNI invocation , contrary to the third step intent

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Full code

Hal_led.h

#ifndef __hal_led_h__ #define __HAL_LED_H__ #include 
Hal_led.c
#define  LOG_TAG  "Myled_hal"    #include  <stdlib.h>  #include   "Hal_led.h"   #include  
Android.mk
Local_path:= $ (call My-dir) include $ (clear_vars) Local_module_path: = $ (target_out_shared_libraries)/hwlocal_module_ TAGS: = optionallocal_module:= myled_hal.defaultlocal_src_files:= hal_led.clocal_shared_libraries: = libutilsinclu De $ (build_shared_library)

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