Who if not we? When if not now?

Find the UTF-8 and UCS value of a character.

wenlong — Mon, 09 Nov 2009 07:09:21 +0000

I write software that processes Chinese characters. Thus, I have to deal with UCS and UTF-8 encoding for Chinese characters. It used to took me quite some time to find or calculate the UTF-8 and UCS value of a Chinese character until I came accross an article about VIM.

I’ve been using VIM for about 8 years but I didn’t know that I can get the UCS and UTF-8 value of a character directly from VIM. To get the value:

Place the cursor on the character, in command mode, then type `ga’ for the unicode value, `g8′ for the UTF-8 value.

VIM saves files in UTF-8 encoding. To see the content of the file in HEX:

`hd filename’ or `hexdump -C filename’

The output will be the same as `g8′.

The first image shows the UTF-8 value of the Chinese character ‘你’. The second image show the UCS value of the same character.

Conky

wenlong — Wed, 04 Nov 2009 13:17:21 +0000

My latest conky setup looks great isn’t it! Too bad wordpress does not allow me to upload my conkyrc and 2 helper scripts.

Issue with java.sql.Time + GWT + browsers in Linux and Windows.

wenlong — Wed, 04 Nov 2009 08:05:21 +0000

Yesterday, I got into a problem with my work. On a Linux machine, I have a database (MySQL) table and there is a column in type time. I use the following java code to retrieve the value:

Time t = rs.getTime("columnName"); // rs is a ResultSet.

The Time objec is sent via HTTP to a GWT web application. The Time object is displayed correctly on a Firefox on linux (00:00:00) but not on a Firefox or IE on Windows (00:30:00).

No matter what value is in the database, the browsers on Windows will display it with an additional 30 mins.

My search starts with Java, JVM, tzdata. Test, trail and error for more than 1 day, finally, the error is the javascript engine. To understand the whole story, I must start with Java.

Base on the javadoc, java.sql.Time is actually a Date object. The date related fields should be set to 1970-Jan-01 and left untouced. Only the time part of it is (should be) used. When the value is read from database, a Time object is created. It is set to 1970-Jan-01 (Asia/Kuala Lumur). Base on the tzdata, the offset for “Asia/Kuala Lumpur” on 1970-Jan-01 is only +7:30 instead of +8:00. Thus, the Time object will have the value -27000000 (which means 00:00:00 +0:00 on 1970-Jan-01).

When this data is sent to the GWT application, the javascript engine in a Linux browser, correctly use the +7:30 offset. Thus, -27000000 plus +7:30 is 00:00:00. But on both Windows browsers, the offset used is +8:00. Thus, -27000000 plus +8:00 is 00:30:00.

To prove this: create a HTML file with the following content and open it with Firefox or epiphany on Linux, then do the same with IE or Firefox on Windows. Maybe another reason to use Linux instead of Windows:

Running Windows XP in Debian using QEMU

wenlong — Mon, 28 Sep 2009 05:09:30 +0000

I’m using Debian for my work. Recently, I need to use a tool that will only run on a Windows XP. To setup a Windows XP using QEMU is the solution:

Install and build the required packages.
# aptitude install qemuctl qemu-launcher # aptitude install kqemu-common kqemu-source # m-a prepare # m-a auto-install kqemu # modprobe kqemu # echo kqemu >> /etc/modules
Run the qemu-launcher.
Check the “Use CD-ROM” checkbox and put your Windows XP installer CD into your CD-ROM drive.
For the “Boot disk” drop-down-list, select “CD-ROM”.
Create the “Hard disk 0″ by clicking the “New” button.
Change the “RAM (MB)” to what you want. I’m using “512″.
Now, your virtual machine has one harddisk, boots from your CD-ROM and has 512 MB RAM.
Click the “Launch” button to start your virtual machine. Usual Windows XP installation follows.

The installation process took a long time to complete (much longer than a usual XP installation), but it runs as fast as (if not faster than) a usual XP installation.

* I experience 2 crashes during the installations. Maybe I was just unlucky.

** You can also use an ISO image as your Windows XP installer CD. Just replace the “CD-ROM” setting from “/dev/cdrom” to “/some/directory/to/your/XP.iso”.

*** To enable widescreen support, select the “Standard VGA card with VESA Bochs extensions” under “Video card” section, in the “Hardware” tab.

**** ctrl+alt+f to go into fullscreen mode. ctrl+alt+f again to switch back to window mode.

Debian lenny on TwinHead M95

wenlong — Thu, 10 Sep 2009 14:59:36 +0000

After more than 3 years of heavy use, my Acer Aspire 5540 has retired. I just got a TwinHead M95. The following is what I did to install Debian on it. By the way, I’m now writing this blog using the M95 and Debian.

Boot with Debian r5.0 DVD (disc 1) and follow the installation to the end.
After the default installation:
1. Wrong screen resolution and no 3D rendering.
2. No way to adjust screen brightness. The hotkeys (Fn + F6/7) are not working.
3. No Wireless network.
To get the correct screen resolution and 3D rendering.
1. aptitude install binutils make gcc glibc
2. Download nvidia linux driver from http://www.nvidia.com/object/unix.html
3. Shutdown GDM
  # /etc/init.d/gdm stop
4. Invoke the nvidia linux driver installation:
  # ./NVIDIA-Linux-x86-185.18.36-pkg1.run
5. Restart GDM
  # /etc/init.d/gdm restart
6. For detail explanation, see http://wiki.debian.org/NvidiaGraphicsDriversNvidiaWay
To adjust the screen brightness.
1. The screen brightness can be adjusted by using the “nvidia-settings”. It is installed automatically when you install the nvidia driver.
2. The screen brightness will always go back to the default after the X is restarted or after lock/unlock the screen. By starting the “nvidia-s
  ettings”, the screen brightness will go back to what you have set in the “nvidia-settings”.
3. Haven’t found a way to enable Fn + F6/7 for controling the screen brightness.
To enable wireless network.
1. Add lenny-backports into the /etc/apt/source.list
  # echo “deb http://www.backports.org/debian lenny-backports main contrib non-free” >> /etc/apt/source.list
2. Get the list of backports packages.
  # aptitude update
3. Install backports keyring to avoid warnings.
  # aptitude -t lenny-backports install debian-backports-keyring
4. Install the new kernel and firmware that can make use of the wireless chipset.
  # aptitude -t lenny-backports install linux-image-2.6.30-bpo.1-$(uname -r | sed ’s,.*-,,g’) firmware-ralink
5. Configure your network interface. My “/etc/network/interfaces” has the following entries:
  - auto ra0
  - iface ra0 inet dhcp
  - wpa-key-mgmt WPA-PSK
  - wpa-pairwise CCMP TKIP
  - wpa-group CCMP TKIP
  - wpa-ssid
  - wpa-psk
6. Reboot your laptop. Choose to boot into the new kernel you just installed (the first one in the list).
7. Bring up your wireless interface.
  # ifup ra0
  Make sure your wireless LED is on (Press Fn + F1 on your keyboard). If the LED is not on, you may get a kernel failure, like I did.
8. For details, see http://wiki.debian.org/rt2860sta
END

Credit Card Check Digit

wenlong — Mon, 07 Sep 2009 08:26:26 +0000

A Credit Card number usually consist of 3 parts:

Issuer ID (left most 6 digits)
Account Number (9 digits)
Check Digit (right most 1 digit)

All valid credit cards fulfill a validation check called “Luhn Check”. The algorithm of Luhn Check is simple:

Double each odd position digit of the credit card number.
If the resulting number is 2 digits, add the two digits.
Replace all odd position digit with the newly calculated digit.
Add up all 16 digits and divide by 10.
If the total can be perfectly divided by 10, it satisfy the “Luhn Check”.

Example:

Sample credit card number (Visa): 4111 1111 1111 1111
Double the odd position digits: 8121 2121 2121 2121
Add up all 16 digits: 8+1+2+1+2+1+2+1+2+1+2+1+2+1+2+1= 30
30 can be perfectly divided by 10, so the credit card number fulfills the “Luhn Check”.

Example 2:

Sample credit card number (Master Card): 5500 0000 0000 0004
Double the odd position digits (the first digit is 10=>1+0=>1): 1500 0000 0000 0004
Add up all 16 digits: 1+5+0+0+0+0+0+0+0+0+0+0+0+0+0+4= 10
10 can be perfectly divided by 10, so the credit card number fulfills the “Luhn Check”.

For a more detail explanation, see http://www.thetaoofmakingmoney.com/2007/04/12/324.html

Cairo-dock

wenlong — Thu, 06 Aug 2009 12:04:17 +0000

I’ve been using Apple-like dock since one or two years ago. I started with wbar which is simple and works great as an application launcher. Early this year, Istarted to use Avant-window-navigator. This one is much advance compare to wbar. It is not only a launcher, but also provide many applets (although some of them does not work for me), a window list and a pretty system tray.

Today, I installed Cairo-dock. This is the best dock I’ve ever used. It provides nearly all features found in wbar and AWN, and much more. It’s an amazing dock! I’m surprised that I didn’t find it earlier. I’ve been using it for the whole day. It’s pretty stable (only crash a few times when I was playing with some applets and configurations) for normal use. Installation is easy (with debian package repo) and it comes with a configuration tool which is easy to use. The only thing missing is a proper system tray applet. I really like the one in AWN. Anyway, this is the best dock I have now. Thanks to the people who write this Cairo-dock.

Cairo-dock http://www.cairo-dock.org/
Avant-window-navigator http://wiki.awn-project.org/
wbar http://freshmeat.net/projects/wbar/

《沙巴行》Day 5

wenlong — Thu, 16 Jul 2009 13:27:51 +0000

第五天也就是沙巴行的最后一天了。由于是早上九点多的飞机，最后一天是什么节目也没有的。吃了早餐，我们就往机场出发。在机场有一间售卖冷冻海鲜的商店。被冷冻的鱼用保鲜纸非常好的包着。非常的卫生、干净。其他人都买了一些，除了我之外。因为我回KL，没人会煮嘛。上了飞机，这次的旅程也就画上了句点。

《沙巴行》Day 4

wenlong — Sat, 11 Jul 2009 16:30:57 +0000

那天，我是最迟起身的一个。不晓得怎么会睡得这么熟吃过早餐，在Rose Cabin四周走走看看。Rose Cabin 的后方有个花圃，再下去就是一大片的菜园，梯级式的。这时候，神山也非常清楚的展现眼前。变幻莫测的云朵，这一分钟几乎将整座山给笼罩着，下一分钟又将神山清清楚楚的让你看个够。

退房后，我们就朝国家公园出发。国家公园的入口处离Rose Cabin只有约十分钟的车程。入门票每人三令吉。坐在车里绕着公园里的柏油路前进。不久我们就到达了攀爬神山的其中一个起点：Timpohon。我们在这儿下车，又是四处走走看看、拍拍照。就这样停停走走了一个小时左右，我们又回到了国家公园的入口处。说真的，好像什么收获也没有。

离开了国家公园，下一站是温泉和瀑布。入门票每人三令吉（之后才发现，门票是通用的。这里也是国家公园）。由于温泉区人满为患，我们打算先去瀑布那儿感受一下山水的凉快！这时候我离群先行一步。可是啊，却走错了方向。走了许多冤枉路，但也把附近的小径给走了个明白。等我到达瀑布时，其他人早就到了。一个个都已经泡在那冰凉的水里。瀑布并不大，但没关系，因为除了我们六个人之外，一个外人都没有。真像个私人泳池，而且是建筑在山林间的，感觉非常棒！说是泡水，但那水真的是太冰凉了。没泡多久我们就坐在池边的石头上，只有脚板和部分的小腿仍在水中。这时候，池里的小鱼便游过来给我们做“去死皮”的 therapy。二、三十条像孔雀鱼般大小的小黑鱼，在脚板和脚趾上吸啊吸的。感觉有点痒、有点怪、很特别。就这样接受了十到十五分钟的 therapy 后，我们才离开瀑布。临走时才开始有人到来。往回走的路上，碰到了不少要到瀑布的人们。我们一行人霸占了整个瀑布这么久，真是幸运。

回到温泉区，人还是那么多。霸了个小井，等那温泉水，可就是怎么也注不满。泡在那不到一尺深的水里，感觉有点好笑。就这么说说笑笑的泡了一会儿，大家就起身冲凉去。离开后，我们就往亚庇出发。

六点多到亚庇，天也黑了。我们就到一家海鲜餐馆吃晚餐。由于不晓得价钱如何，海月谨慎的点了一些海鲜料理。吃完后结帐，每个人只是二十多令吉！我的天啊，真想再吃一轮！

吃饱喝足，我们往亚庇市区找住处去了。由于选择太多了，所以没有预先定房。可是，我们吃惊的发现，所有的旅店都爆满！找了一间又一间，都是徒劳。最后，海月的舅母帮我们打听到了一家还有空房的旅店，而且离机场不远。旅店的设备不错，就是价钱贵了些。Standard room 就要 RM176。加床另加 RM50 ，而且要 Deluxe room （RM198）才可加床。这是我们这趟旅程中最不值的花费。不过最后能找到一个可以休息的地方，也算是幸运的了。

越过尽头处的铁闸，便是攀山旅程的开始。

《沙巴行》Day 3

wenlong — Sun, 05 Jul 2009 16:44:08 +0000

第三天，原本的计划是到西巴丹岛浮潜，由于拿不到准证，我们就打算提早搭十一点钟的船离开。吃完自由餐早餐后，还有几个小时的时间，我们又到岛上逛逛。这一次，我们横越了整个小岛，去到了Mabul岛的另一边。说“横越”是夸张了，Mabul岛的宽度好像还不到一公里呢！

岛的这一边住着不少人，最不同的是这里的居住环境，比起前一天的，简直好得太多太多了。房屋盖得结实、有油漆，人们的衣着算是光鲜，道路两旁种着花花草草，有流行曲从屋里传出，最后这里还有一件小学。当天是星期五，可是却没有人在上课，奇怪。

再往前走，我们抵达了一处度假村。岛上的度假村和水上的度假村有着很大的分别。这里绿树如荫，躺在网床上多么享受。多走几步就是沙滩、大海，想晒太阳、打排球或游泳，任君选择。不过到了晚上，应该会有蚊子吧！这度假村还有一部分是建在海上的，价格也是这里最贵的，我们也走去参观参观。说真的，外观并不怎么样，度假屋又比较小，可能里头的装璜比较好吧。离开时看到了一只大海龟！没想到不需出海也能看见海龟啊！

搭上十一点的船，我们离开了Mabul岛。到了仙本那，再次挤满海月舅舅的ISUZU D-Max，我们往神山出发。大半天的车程，中途有停下吃午餐、晚餐、拍照、买东西。到达Rose Cabin时，天早就全黑了。神山就在面前，但是没月亮，什么也看不见。位处山上、冷风索索，快快冲个热水澡，见周公去了。

后记：我想，生活条件极差的岛民可能是从菲律宾非法入境的。不然的话，这么大的生活素质上的差别要如何解释呢？

这就是岛上唯一的小学。

岛上度假村的优点就是绿树和沙滩。

就是它了，我们在Mabul岛的最后一个惊喜。