find/grep command

The following command searches C/C++ source code to find the content of "equalizer".

$ find ~/myspace/git/opencore -type f -name "*.[ch] -o -name "*.cpp" -exec grep -I "equalizer" {} \; -print

ubuntu - recording

I use "alsamixer -c 0" to set up my recording with microphone.

ubuntu 8.04 - wireless network setup

I spent less than 9 hours to setup my wireless card on ubuntu. When use "lspci" command, I get the name of my wireless card, which is "AR2413 802.11bg".

Here is the brief.

1. disable the Atheros proprietary drivers from "system->adminstrator->hardware drivers"
2. unplug the wired ethernet line

3. extract ndiswrapper-1.55.tar.gz, and make & sudo make install

4. extract madwifi-hal-0.10.5.6-r3835-20080801.tar.gz, make & sudo make install

5. extract Wireless_Atheros.zip, use ndisgtk to install the net5211.inf
or
$ sudo ndiswrapper -a XXXX:YYYY ath0 (here XXXX:YYYY is get from lspci -n for Atheros card)

6. setup
add ndiswrapper at the end of /etc/modprobe.d/blacklist
add ath_pci at the end of /etc/modules

$ sudo iwconfig
$ sudo lshw -C network
$ iwlist scan (to find my wireless network)
$ sudo network-admin (which should setup wireless network)

check the following configuration at /etc/network/interfaces
=======================
iface ath0 inet dhcp
wireless-key XXXX
wireless-essid fade

auto ath0
=======================
Here XXXX is my wep password.
call "/etc/init.d/networking restart" to restart

I also installed wpa_supplicant but it does not seem to be needed.

After I reboot the OS, I found the system could not find ath0, so what I did is "sudo modprobe wlan_scan_sta" and reboot again, this time ath0 appears.

fedora 10 - setup i686 environment for android (1)

0. install git ($ sudo yum install git)
1. Download JDK 5.0 (jdk-1_5_0_19-linux-i586-rpm.bin) from sun

   $ cd /usr/local
   $ /tmp/jdk-1_5_0_19-linux-i586.bin 
   $ sudo updatedb
   $ locate javac | grep bin
   /usr/local/jdk1.5.0_19/bin/javac          (the result)
   $ sudo /usr/sbin/alternatives --install /usr/bin/java java /usr/local/jdk1.5.0_19/bin/java 100 
   $ sudo /usr/sbin/alternatives --install /usr/bin/jar jar /usr/local/jdk1.5.0_19/bin/jar 100  
   $ sudo /usr/sbin/alternatives --install /usr/bin/javac javac /usr/local/jdk1.5.0_19/bin/javac 100
   $ sudo /usr/sbin/alternatives --config java

2 Play with curl

$ cd ~/bin (make sure ~/bin is in $PATH)
$ curl http:/android.git.kernel.org/repo > ~/bin/repo
$ chmod a+x ~/bin/repo
$ cd ~/myspace/mydroid
$ repo init -u git://android.git.kernel.org/platform/manifest.git -b cupcake
$ repo sync

mips - the next example

This example access an array which is a block of buffer.

/* bar initialize input (or 3 to each element)
 */
int bar(int* in, int n)
{
    int ret;
    __asm__(
    ".set push     \n"       // save assembler option
    ".set noreorder\n"       // suppress reordering
    "lw $9, %2     \n"       // $9 = n (counter end)
    "li $8, 0      \n"       // $8 = 0
    "li $12, 0     \n"       // $12 = 0
    "move $4, %1\n"          // $4 = in
    "loop:  \n"             
    "lw $11, ($4) \n"        // $11 = *in   
    "ori $11, $11, 3  \n"    // $11 = $11 || 3 
    "sw $11, ($4) \n"        // *in = $11
    "addi $4, $4, 4 \n"      // in++  (move to next addess)
    "addi $8, $8, 1 \n"      // move to next sample
    "bne $8, $9, loop \n"    // loop
    "sw $11, %0    \n"        // save $12 to ret
    ".set pop     \n"        // restore assembler option
    : "=m" (ret)             // to return
    : "r" (in),"m" (n)       // the input
    );
    return ret;
}

Here the use of $8 is not the best, because the move the array element is by $4, soe the $8 is not most necessary, because $4 can be used to check the range for the loop.

mips - a first example

In the following sample, it shows how to send the input (val) and the output (ret) to assembly block.

/* foo returns (val | 3)
 */
int foo(int val)
{
    int ret;
    __asm__(
    ".set push\n"              // save assembler option
    ".set noreorder\n"         // suppress reordering
    "ori  $2, %1, %2\n"
    "sw $2, %0\n"              // save $2 to ret
    ".set pop\n"               // pop assembler option
    : "=m" (ret)               // ret: memory
    : "r" (val), "n" (3)       // val: read-only register, n: number
    );
    return ret;
}

The real code by dump is:

08804554 :
 8804554: 27bdffd0  addiu sp,sp,-48
 8804558: afbe0020  sw s8,32(sp)
 880455c: 03a0f021  move s8,sp
 8804560: afc40010  sw a0,16(s8)
 8804564: 8fc20010  lw v0,16(s8)
 8804568: 34420003  ori v0,v0,0x3
 880456c: afc20000  sw v0,0(s8)
 8804570: 8fc20000  lw v0,0(s8)
 8804574: 03c0e821  move sp,s8
 8804578: 8fbe0020  lw s8,32(sp)
 880457c: 27bd0030  addiu sp,sp,48
 8804580: 03e00008  jr ra
 8804584: 00000000  nop

android notes - the process of development

0 installation and setup
1 create a project

$ android create project --target 1 --path ./demo --activity demo --package com.example.demo

2 edit source code ~/myspace/demo/src/example/demo/demo.java
3 compile with ant

$ ant -debug -verbose

4 run emulator with a script

#! /bin/sh
out/host/linux-x86/bin/emulator -verbose \
 -kernel prebuild/android-arm/kernel/kernel-qemu \
 -ramdisk out/target/product/generic/ramdisk.img \
 -system out/target/product/generic/system.img \
 -init-data out/target/product/generic/userdata.img \
 -avd myavd -sdcard ./sdcard.img -no-skin -no-boot-anim

5 install the application we have build

$ cd ~/myspace/demo
$ adb install bin/demo-debug.apk
$ adb install -r bin/demo-debug.apk (for reinstall)
$ adb shell
# logcat
# ps a (to get process id to kill)
# kill -9

That's on java side, on the android side,
1 setup

$ cd ~/myspace/mydroid
$ source ./build/envsetup.sh
$ lunch 1

2 build the project in android

$ cd ./frames/base/media/libmediaplayerservice
$ mm (it builds libmediaplayerservice library as an example)
$ cd ~/myspace/mydroid (go back to the root)
$ make snod (build the system image

then you can go back to run emulator with parameters specified in the script.