L2CAP数据发送和接收

ACL链路在蓝牙中非常重要,一些重要的应用如A2DP,基于RFCOMM的应用,链路BNEP等都要建立ACL,ACL发送/接收包。跟大家一起来分析ACL包发送/接收流程,以及涉及到的重要命令/事件。 ACL包发送 下面的图(点击大图)是各种应用层使用L2CAP的API:l2ca_datawrite发送数据流的过程,此..
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Android连接过程HFP剖面

包/应用程序/设置/ SRC / COM / Android /设置/蓝牙/ bluetoothdevicepreference.java onclicked() { void 国际bondstate = mcacheddevice。getbondstate(); 如果是(mcacheddevice…
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安卓蓝牙启动发现分析

一。start_discovery的上层一系列的调用 1。界面上的“设备”搜索 在。/设备/ softwinner /普通/包/ tvdsettings / SRC / COM / Android /设置/蓝牙/ bluetoothsettings Java中。 当点击“搜索设备”或者打开时就会去扫描蓝牙…
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之GKI框架Bluedroid

1。概述 GKI以库libbt-brcm_gki。所以(静态库?)的形式提供给Bluedroid使用 该层是一个适配层,适配了OS相关的进程、内存相关的管理,还可以用于线程间传递消息  主要通过变量gki_cb实现对进程的统一管理 typedef struct { pthread_mutex_t gki_mutex; pthread_t…
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Android UI分析恢复

安卓  恢复和Android本质上是两个独立的rootfs,只是恢复这个rootfs存在的意义就是为Android这个rootfs服务,因此被解释为Android系统的一部分。恢复作为一个简单的rootfs,提供了非常有限的几个功能,只包含了几个简单的库,UI的显示采用的是直接刷framebuffer的形式,作为Android 框架…
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Android / Linux系统性能调优

关于性能优化这是一个比较大的话题,今天,想从一些技术细节上谈谈性能优化,主要是一些代码级别的技术和方法。本文的东西是我的一些经验和知识,并不一定全对,希望大家指正和补充。 在开始这篇文章之前,大家可以移步去看一下酷壳以前发表的《代码优化概要》,这篇文章基本上告诉你--要进行优化,先得找到性能瓶颈!但是在讲如何定位系统性能瓶劲之前,请让我讲一下系统性能的定义和测试,因为没有这两件事,后面的定…
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《C Primer Plus》动态链表删除的一个错误

《C Primer Plus》确实是一本伟大的书,但尽信书不如无书,作者史蒂芬煎饼可能也希望他的读者能找到些许他在不经意中出现的小错误吧!  在该书第五版17章”高级数据表示”中,程序清单17.2给出如下代码: #包括 #包括 #包括 #定义tsize 45 # sizeof(struct定义长度电影)…
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排序算法研究

小序 Sort of very important and a very common operation, a bubble sort, selection sort, insert sort, Hill sort, quick sort, heap sort and so on many kinds of methods. Here we introduce the first three sorting algorithms and the implementation of the code, and the rest of the algorithm will be in the follow-up course "data structure" high school learning to. Algorithm is just an idea, in fact, it is now dependent on the data structure, so here to extract some typical algorithms and data structures, including the sort and list / stack / queue structure of the operation. ...
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Fork Bomb Linux

As is known to all, Bash is a very powerful shell, provides a powerful interaction and programming capabilities. Such a shell in nature will not be missing the "function" of this element to help the program to the efficient development and management of modular. Thus resulting from its special characteristics, fork has a bash bomb. Jaromil was designed in 2002 to streamline the implementation of a fork bomb. A malicious program is so-called fork bomb, its internal is a continuous in fork process of infinite loop, fork bomb and...
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Bluedroid framework

Bluedroid project code framework: Bta: 1 Ag (audio gateway): implementation of Bluetooth audio gateway 2 Ar (audio/video registration): the realization of audio / video registration module 3 Av (advanced audio/video): Advanced Audio / video implementation 4 Dm (device mana...
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EMMC driver

Block device is one of the most complex Linux devices, but as stubborn to know its Geek, we always turn the code over and over, to get a thorough understanding of the truth. Of course, quickly learning new things, is the most important, personally feel: kernel MMC / SD card driver architecture is the point to study the EMMC driver. Only by understanding the it in order to truly understand the block device driver. At the same time, in order to truly understand a Linux block device driver. ...
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Introduction of several P2P streaming media open source projects

P2P streaming media open source project introduction 1 PeerCast Founded in 2002, the first open source P2P streaming project. PeerCast nodes in the tree structure, each channel is a tree, the source is the root of the root node, the parent node only to provide data to the child. The farther away from the root node, the greater the transmission delay, so the depth of the tree should be as short as possible, but the limited uplink bandwidth of the node is limited. 2 Tribler The project started in 2008, both to achieve BT download, but also play video on demand and straight...
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WiFi driver for SDIO interface

1, SDIO interface layer analysis SDIO bus SDIO bus and USB bus, SDIO also has two ends, one end is the HOST side, the other end is the end of device. All communications are sent by the end of the HOST command to start, Device end as long as you can parse the command, you can communicate with each other. : HOST CLK signal to DEVICE clock signal transmission, each clock cycle a command. CMD signal: bidirectional signal for transmitting command and response. ...
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Android upgrade script updater-script function introduction

This is the function of Android system to run updater-scripts. Function is the Edify language, when the call to the end of these functions, will return the data to the script. Of course, you can also use the return value of these functions to confirm the success or not, for example: Ifelse (mount ("yaffs2", "MTD", "system", "/system") (ui_print = = "system", "Successfully Mounted!")...
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Performance analysis of Linux and Android systems

As a system engineer for a Linux or Android platform, outside the new function development, main work is to optimize the system performance, to make the system run in the best state, but due to the complexity and variability of hardware, software, network environment, etc., resulting in the system optimization becomes more and more complicated, how to identify performance problems in which, is a big problem for performance optimization, from the viewpoint of system and elaborates due to system software and hardware configuration could result from improper performance problems and to explore the detection system fault and optimize the performance of the general method and procedure. ...
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