android: how to see LOGV message

In your code add  

#define LOG_NDEBUG 0 


The reason is log.h at system/core/include/cutils/log.h

Ex:
In you want to see LOGV in audio_hw.c

You must add


#define LOG_TAG "audio_hw_primary"
#define LOG_NDEBUG 0
#define LOG_NDEBUG_FUNCTION
#ifndef LOG_NDEBUG_FUNCTION
#define LOGFUNC(...) ((void)0)
#else
#define LOGFUNC(...) (LOGV(__VA_ARGS__))
#endif

android: Filter logcat to get only you want message

adb -d logcat your_package_name:log_level *:S

ex: adb -d logcat com.example.example:I *:S



reference:
http://stackoverflow.com/questions/6854127/filter-logcat-to-get-only-the-messages-from-my-application-in-android

audio: concept

@Fetures Overview
The features supported by ALSA SoC Audio driver are:
    -Supports audio codec in ALSA SoC framework.
    -Multiple sample rates support (8 KHz, 16 KHz, 22.05 KHz, 32 KHz, 44.1 KHz, 48 KHz etc) for both capture and playback.
    -Supports audio in stereo mode.
    -Supports simultaneous playback and record (full-duplex mode).
    -Start, stop, pause and resume feature.
    -Supports mixer interface for audio codecs.


@Tool:
tinyalsa are used for audio  playback, capture and configuration.

@ALSA HAL:
mydroid/device/xx/common-open/audio/audio_hw.c
 The compiled HAL is named audio.primary.xxxx.so at /system/lib/hw


@ALSA Soc Architecture
 - ASOC (ALSA System On Chip)
   ASoC) layer is to provide better ALSA support for embedded system on chip processors and portable audio codecs

 - Desgin:
   1.Codec independence:
        Allows reuse of codec drivers on other platforms and machines.
   2.Easy I2S/PCM audio interface setup between codec and SoC.
         Each SoC interface and codec registers it's audio interface capabilities with the
         core and are subsequently matched and configured when the application hw params are known.
   3.Dynamic Audio Power Management (DAPM):
         DAPM automatically sets the codec to it's minimum power state at all times.
         This includes powering up/down internal power blocks depending on the internal codec audio routing
         and any active streams.
   4.Pop and click reduction:
         Pops and clicks can be reduced by powering the codec up/down in the correct sequence
         (including using digital mute). ASoC signals the codec when to change power states.

  -SoC basically splits an embedded audio system into three components:

    1.Codec driver:

The codec driver is platform independent and contains audio controls,
        audio interface capabilities, codec dapm definition and codec IO functions.
    2.Platform driver:
        The platform driver contains the audio dma engine and audio interface drivers (e.g. I2S, AC97, PCM)
        for that platform.
    3.Machine driver:
        The machine driver handles any machine specific controls and audio events
        i.e. turning on an amp at start of playback

@ Device Interface : /dev/snd/
  - PCM devices for recording and play
  - CTL devices that allow manipulating the internal mixer and routing of the card

    1./dev/snd/controlC0: Control devices (i.e. mixer, etc)
    2./dev/snd/pcmC0D0c : PCM Card 0 Device 0 Capture device
    3./dev/snd/pcmC0D0p : PCM Card 0 Device 0 Playback device

@ Proc FS Interface: /proc/asound
    The /proc/asound kernel interface is used as a status and configuration interface.
    A lot of useful information about the sound system can be found in the
    /proc/asound subdirectory.


    1.cards   : List of registered cards
    2.version : Version and date the driver was built on
    3.devices : List of registered ALSA devices
    4.pcm     : The list of allocated PCM streams
    5.cardX   : (X = 0-7)   The card specific directory
    6.cardX/pcm0p : The directory of the given PCM playback stream
    7.cardX/pcm0c : The directory of the given PCM capture stream




@ Sys FS Interface:
  - /sys/devices/platform/soc-audio/ : Information on the codec device
  - /sys/devices/platform/xxx-pcm-audio : Interface for platfrom pcm (ALSA) device
  - /sys/devices/platfrom/xxx-mcbsp-dai.x : Interface for McBSP device


@ Commonly Used API for ALSA:

    snd_pcm_open:
        Opens a PCM stream

    snd_pcm_close:
        Closes a previously opened PCM stream

    snd_pcm_hw_params_any:
         Fill params with a full configuration space for a PCM

    snd_pcm_hw_params_test_ <>:
        Test the availability of important parameters like number of channels,
        sample rate etc.
        For e.g. snd_pcm_hw_params_test_format, snd_pcm_hw_params_test_rate etc.

    snd_pcm_hw_params_set_ <>:        Set the different configuration parameters.
        For e.g. snd_pcm_hw_params_set_format, snd_pcm_hw_params_set_rate etc.

    snd_pcm_hw_params:
        Install one PCM hardware configuration chosen from a configuration space

    snd_pcm_writei:
        Write interleaved frames to a PCM

    snd_pcm_readi:
        Read interleaved frames from a PCM

    snd_pcm_prepare:
        Prepare PCM for use

 snd_pcm_drop:
        Stop a PCM dropping pending frames

    snd_pcm_drain:
        Stop a PCM preserving pending frames


reference:
http://processors.wiki.ti.com/index.php/UserGuideAudioDriver_PSP_04.02.00.07

Enabling dev_dbg in the kernel

Enabling dev_dbg in the kernel
To enable dev_dbg messages in a specific kernel file:

#define DEBUG

before including 

Reference: https://lkml.org/lkml/2007/6/29/323

android: lcd backlight

1. packages/apps/Settings/src/com/Android/settings/BrightnessPreference.java

2.frameworks/base/core/java/Android/os/IPowerManager.aidl.java
   --> // sets the brightness of the backlights (screen, keyboard, button) 0-255
    void setBacklightBrightness(int brightness)

3.frameworks/base/core/java/Android/os/PowerManager.java

    public void setBacklightBrightness(int brightness)
    { 
        try {
            mService.setBacklightBrightness(brightness);
        } catch (RemoteException e) { 
        }
    } 


4.frameworks/base/services/java/com/Android/server/PowerManagerService.java

 -- >public void setBacklightBrightness(int brightness) {   

5.frameworks/base/services/java/com/android/server/LightsService.java

 public void setBrightness(int brightness) {
            setBrightness(brightness, BRIGHTNESS_MODE_USER);
        }

        public void setBrightness(int brightness, int brightnessMode) {
            synchronized (this) {         
                int color = brightness & 0x000000ff;
                color = 0xff000000 | (color << 16) | (color << 8) | color;
                setLightLocked(color, LIGHT_FLASH_NONE, 0, 0, brightnessMode);
            }
        }







6./frameworks/base/services/jni/com_android_server_LightsService.cpp
 

static void setLight_native(JNIEnv *env, jobject clazz, int ptr,

        int light, int colorARGB, int flashMode, int onMS, int offMS, int brightnessMode)

{

    Devices* devices = (Devices*)ptr;

    light_state_t state;

    if (light < 0 || light >= LIGHT_COUNT || devices->lights[light] == NULL) {

        return ;

    }

    memset(&state, 0, sizeof(light_state_t));

    state.color = colorARGB;

    state.flashMode = flashMode;

    state.flashOnMS = onMS;

    state.flashOffMS = offMS;

    state.brightnessMode = brightnessMode;

    devices->lights[light]->set_light(devices->lights[light], &state);

}

7. devices/vendor/board/liblights.c


set_light_backlight(struct light_device_t* dev,
        struct light_state_t const* state)                                                                                                                             
{
    int err = 0;
    int brightness = rgb_to_brightness(state);                                                                                                                         
    int fd;
    char buf[1]={0};

    pthread_mutex_lock(&g_lock);  
    fd = open(LCD_FILE, O_RDONLY);
    err=read(fd, &buf, 1);
    close(fd);
    if(buf[0] == '0' && brightness)   
        usleep(200000);
    err = write_int(LCD_FILE, brightness);
    pthread_mutex_unlock(&g_lock);                                                                                                                                     

    return err;
}

char const*const LCD_FILE
        = "/sys/class/leds/lcd-backlight/brightness";




8. kernel/driver/leds
ex: kernel/driver/leds/xxxx-pwm.c

vim: marked word

- 使用 vim 來註解一整段文字  -----------------------------------------------
‧執行 apt-get install vim-addon-manager vim-scripts
‧執行 vim-addons install enhanced-commentify
‧執行 vim 某個 文字檔,進入vim：

  1. 先按 Esc 離開 insert mode
  2. 再按 ctrl+v 將要註解的這幾行選取(使用上下左右鍵 or + shift )
  3. 再按大寫的 I (指的是進入Insert mode)
  4. 再輸入 #
  5. 最後按 Esc 就會看到選取的這幾行都被 # 註解掉了

linux screen: command list

Key	Action	Notes
Ctrl+a c	new window
Ctrl+a n	next window
Ctrl+a p	previous window
Ctrl+a “	select window from list
Ctrl+a Ctrl+a	previous window viewed
Ctrl+a S	split terminal horizontally into regions	Ctrl+a c to create new window there
Ctrl+a |	split terminal vertically into regions	Requires debian/ubuntu patched screen 4.0
Ctrl+a :resize	resize region
Ctrl+a :fit	fit screen size to new terminal size	Ctrl+a F is the same. Do after resizing xterm
Ctrl+a :remove	remove region	Ctrl+a X is the same
Ctrl+a tab	Move to next region
Ctrl+a d	detach screen from terminal	Start screen with -r option to reattach
Ctrl+a A	set window title
Ctrl+a x	lock session	Enter user password to unlock
Ctrl+a [	enter scrollback/copy mode	Enter to start and end copy region. Ctrl+a ] to leave this mod
Ctrl+a ]	paste buffer	Supports pasting between windows
Ctrl+a >	write paste buffer to file	useful for copying between screens
Ctrl+a <	read paste buffer from file	useful for pasting between screens
Ctrl+a ?	show key bindings/command names	Note unbound commands only in man page
Ctrl+a :	goto screen command prompt	up shows last command entered

refer: http://deep.tw/others/screen/split-vertical.html

linux screen : vertical and horizontal

vertical: ctr_a + |
horizontal : ctr_a + S

git & vimdiff setting

ref:http://stackoverflow.com/questions/3713765/viewing-all-git-diffs-with-vimdiff

#git config --global diff.tool vimdiff
#git config --global difftool.prompt false
#git config --global alias.d difftool


You type #git d

exit #wq:

git log

http://gitready.com/advanced/2009/01/20/bend-logs-to-your-will.html

#git log -n
 
show all content

#git log -p 


show one line
#git log -pretty=oneline


show graph 
#git log --graph