repo -b

repo 是 google 在 Android Open Source Project 導入的原始碼管理工具,  用來同步許多 git repository 的動作, 同時也協助 source code review server 溝通。
用 repo 來開始抓遠端的 source code 時, 必須先指定 URL 及想抓取的分支, 如以下的指令就是抓出 AOSP 上 tag 為 android-4.0.1_r1 的版本 :

$ repo init -u https://android.googlesource.com/platform/manifest -b android-4.0.1_r1

在下 repo sync 之前, 可以先看看抓下來的 manifest.xml 檔案 :

$ cat .repo/manifest.xml  | head -9
<!--?xml version="1.0" encoding="UTF-8"?-->
<manifest>

 <remote  name="aosp" <="" p="">
           fetch=".." />
 <default <="" p="" revision="refs/tags/android-4.0.1_r1">
           remote="aosp"
           sync-j="4" />

很明顯, 剛剛所下的分支版號就紀錄於此, 此時我們再下一次 init, 改抓另個分支 :

$ repo init -b android-2.3.7_r1
.repo/manifests/: manifest switched android-4.0.1_r1...android-2.3.7_r1
.repo/manifests/: discarding 10 commits removed from upstream

再看一次 manifest.xml :

$ cat .repo/manifest.xml | head -9
<!--?xml version="1.0" encoding="UTF-8"?-->
<manifest>

  <remote  name="aosp" <="" p="">
           fetch=".." />
  <default <="" p="" revision="refs/tags/android-2.3.7_r1">
           remote="aosp"
           sync-j="4" />

的確紀錄的版本改變了, manifest.xml 上面所紀錄的分支名稱, 會用來當執行 repo sync 時, 把各個 git repository 照這分支抓下來。

$ repo sync bionic
Downloading bionic: 100% (3MB/3MB), done.
...
Unpacking objects: 100% (61/61), done.
From https://android.googlesource.com/platform/bionic
...
Fetching projects: 100% (1/1), done.

$ cd bionic/
$ git branch -a
* (no branch)
...
  remotes/m/android-2.3.7_r1 -> refs/tags/android-2.3.7_r1

此時抓下來的分支, 就是後面改設的 android-2.3.7_r1, 這時試著改切回 4.0.1_r1 的分支

$ repo init -b android-4.0.1_r1
.repo/manifests/: manifest switched android-2.3.7_r1...android-4.0.1_r1
.repo/manifests/: discarding 1 commits removed from upstream

$ repo sync bionic
Fetching projects: 100% (1/1), done.

$ cd bionic/
$ git branch -a
* (no branch)
...
  remotes/m/android-2.3.7_r1 -> refs/tags/android-2.3.7_r1
  remotes/m/android-4.0.1_r1 -> refs/tags/android-4.0.1_r1

可以看到有兩個跟遠端的依從關係, 理論上這裡紀錄了 local repository 跟 remote repository 分支版本的關係, 這裡的資訊會來 commit 檔案到遠端的時候, 選擇正確的 branch, 不過這裡我尚無法實驗釐清。

當我們單獨 git clone 一個 project 時, -b 亦會產生相同的效果

Vibrator function support in Android

Android application connect to HAL by JNI interface, for vibrator, the JNI interface is defined very simple.


JNI: frameworks/base/services/jni/com_android_server_VibratorService.cpp


static jboolean vibratorExists(JNIEnv *env, jobject clazz)
{
    return vibrator_exists() > 0 ? JNI_TRUE : JNI_FALSE;
}


static void vibratorOn(JNIEnv *env, jobject clazz, jlong timeout_ms)
{
    // LOGI("vibratorOn\n");
    vibrator_on(timeout_ms);
}

static void vibratorOff(JNIEnv *env, jobject clazz)
{
    // LOGI("vibratorOff\n");
    vibrator_off();
}

static JNINativeMethod method_table[] = {
{ "vibratorExists", "()Z", (void*)vibratorExists },
{ "vibratorOn", "(J)V", (void*)vibratorOn },
{ "vibratorOff", "()V", (void*)vibratorOff }
};

vibratorOn, vibratorOff and vibratorExists just simple wrapper of vibrator_on, vibrator_off and vibrator_exists, which is provide by device maker, through HAL interface.

HAL: hardware/libhardware_legacy/vibrator/vibrator.c


#define THE_DEVICE "/sys/class/timed_output/vibrator/enable"


int vibrator_exists()
{
    int fd;


#ifdef QEMU_HARDWARE
    if (qemu_check()) {
        return 1;
    }
#endif


    fd = open(THE_DEVICE, O_RDWR);
    if(fd < 0)
        return 0;
    close(fd);
    return 1;
}



int vibrator_on(int timeout_ms)
{
    /* constant on, up to maximum allowed time */
    return sendit(timeout_ms);
}


int vibrator_off()
{
    return sendit(0);
}

HAL call into kernel space by sysfs, path at "/sys/class/timed_output/vibrator/enable"
It's a Android designed feature, a timed_output or timed_gpio device.

If you echo 10000 into this sysfs, then it will vibrate for ten seconds :

$ echo 10000 > /sys/class/timed_output/vibrator/enable 

If you cat it during the vibration, you will saw how many ms before it back to quiet :

$ cat /sys/class/timed_output/vibrator/enable

315

Inside kernel space, Android defined two new platform driver to be use for vibrator : timed_gpio and timed_output.

By grab HC kernel source that released by Acer/ASUS, found that they are using different of implementation.

Acer use a gpio pin, config with a timed_gpio driver, hook up with platform_device driver, and also to timed_output driver to provide vibrator interface from sysfs.

ASUS use an IC max1749, directly register a timed_output interface to provide vibrator interface from sysfs.

PS. Beside kernel source, above source code is trace from AOSP 4.0.1.

Android-x86 ginerbread build failed

Same as below :

https://groups.google.com/group/android-building/browse_thread/thread/e9baa16a0b1e96f

Inside fedora14, update "make", then problem solved.
So seems newer version of make had released.

pidof script of mac OSX

Found at http://hints.macworld.com/article.php?story=20030618114543169

#!/bin/sh
ps axc|awk "{if (\$5==\"$1\") print \$1}";

Interface builder

Can't connect outlet from rounded button to file's owner.

Found same issues :
http://stackoverflow.com/questions/1746281/cant-connect-iboutlet-in-interface-builder


Solved by read class file again, wired !

SSH Over USB

From iPhone Development Wiki

SSH over USB using usbmuxd Tested on OS X. Works on Windows too, according to the README

• Get usbmuxd source package and unpack
• Go into folder python-client
• chmod +x tcprelay.py
• Run ./tcprelay.py -t 22:2222

Now you can log into your device via ssh root@localhost -p 2222
The -t switch tells tcprelay to run threaded and allow more than one ssh over the same port.
See ./tcprelay.py --help for further options.

Log from : http://iphonedevwiki.net/index.php/SSH_Over_USB