It is offten desired to get a value from DataReader using column name with known Type. For example you want to get a string value of column ‘first_name’ and int value of column ‘account_number’. The following extension method makes it easy to fetch values from a DataReader using Type and column name:

public static class ReaderHelper
{
    public static bool IsNullableType(Type valueType)
    {
        return (valueType.IsGenericType &&
            valueType.GetGenericTypeDefinition().Equals(typeof(Nullable<>)));
    }

    public static T GetValue<T>(this IDataReader reader, string columnName)
    {
        object value = reader[columnName];
        Type valueType = typeof(T);
        if (value != DBNull.Value)
        {
            if (!IsNullableType(valueType))
            {
                return (T)Convert.ChangeType(value, valueType);
            }
            else
            {
                NullableConverter nc = new NullableConverter(valueType);
                return (T)Convert.ChangeType(value, nc.UnderlyingType);
            }
        }
        return default(T);
    }
}

It can be used as:

User GetUser(IDataReader reader)
{
    User user = new User();
    user.FirstName = reader.GetValue<string>("first_name");
    user.LastName = reader.GetValue<string>("last_name");
    user.Email = reader.GetValue<string>("email");
    user.AccountNumber = reader.GetValue<int>("account_number");
    user.NumberOfVehiclesOwned = reader.GetValue<int?>("vehicle_count"); // nullable data field
    return user;
}

I recently purchased U.S Robotics USR5465 router. I chose it because it had 4MB flash and 16MB ram; enough to run  linux based distribution for router such as OpenWRT. Out of the box, this router runs linux kernel 2.4 along with busy box. But I was very much interested to run latest kernel (2.6.x) on it. With OpenWRT it is easy to create the development environment. Just login to your favorite linux as a non-root and follow few steps mention here. Once you configure your router kernel and run make command. OpenWRT automatically downloads required toochain source and compiles it for your PC.

USR5465 has one serial port and possibly a 12 pin JTAG. So, I brought myself a Nokia DKU-5 cable (SN: WT048000317).  This cable has a usb to serial converter; and it’s cheap! I cut/removed the phone connector end of the cable. After a little research, I found out that:

Phone connector Pin#        Wire Color        Signal
            8                 RED              GND
            7                 GREEN            TX
            6                 WHITE            RX
            4                 ORANGE           3.3 OUT  (Not used, do not connect!!)

After connecting wires to jumper J301, compiling ark3116 kernel module and using 115200 baud rate with 8-N-1, I was able to connect my laptop to the router. When I restarted the router I saw the boot messages from router. Here is how I connected the wires:

j301
|o|  --->   GREEN   (TX)
|o|  --->   WHITE   (RX)
|o|
|o|  --->   RED     (GND)

______
o -> Power led

#################################     <--- Motherboard edge

Another advantage of this router is that it has a USB 2.0 port. To use usb, I had to use revision 13088 and patched it using this patch

svn checkout -r13088 https://svn.openwrt.org/openwrt/trunk kamikaze
patch -p1 < kamikaze-r13088-b43ssb-2.6.27.diff

I had to change “BUSWIDTH 2″ to “BUSWIDTH 1″ in drivers/mtd/maps/bcm47xx-flash.c file in order to get a working image. Otherwise I saw few “error -5″ lines after booting.

I wasn’t able to connect to the internet, even after I got the image to boot successfully. I found that the problem was due to incorrect labeling of the WAN and the LAN ports by OpenWRT.  Since I was able to connect to the router using the serial port I changed the VLAN config in /etc/config/network to:

#### VLAN configuration
config switch eth0
        option vlan0    "0 1 2 3 5*"
        option vlan1    "4 5"

Only then I was able to get a valid IP address and connect to the internet.

Other than wireless (which didn’t bother me, as I always use wired connection) everything is now working perfectly. Since this model is not supported by OpenWRT, it doesn’t know the led configurations and does not recognize the model. So I had to add that info. in diag.c file. gpioctl utility was useful to find out the led and  reset button gpios.

You can download modified diag.c from here. Once you compile you should see WAN led and USB led litup (need to do some configuration for USB led).

Further I was also able to install VPNC on the router and connect to CISCO VPN without any problem This makes it easier for me when using Vista x64, as cisco doesn’t provide vpn client for 64bit windows.

I recently switched to “dark” vs2008 color scheme since it is easy on eyes.

I started with RagnaRok color scheme created by Tomas Restrepo and modified it to my convenience.

You can download the modified version from here: RagnaRok-modified.

I added the ability to rotate string right or left. Here is the code:

public enum Direction { Right, Left }

string rotateString(string source, int rotationCount, Direction direction)
{
    if (String.IsNullOrEmpty(source) || rotationCount <= 0)
        return source;

    int pivot = 0;
    List<int> delimiterLocations = new List<int>();
    char[] sourceChars = new char;

    char temp;
    // Reverse the whole string and
    // save the dilimiter locations
    for (int i = 0; i < source.Length; i++)
    {
        sourceChars = source[i];

        if (source[i] == ' ')
            delimiterLocations.Add(source.Length - i - 1);
    }

    // calculate neededDelimiters mod wordCount
    // (assume words = delimiterCount + 1)
    pivot = rotationCount % delimiterLocations.Count;

    if (pivot > 0)
    {
        if (direction == Direction.Left)
            pivot = delimiterLocations.Count - pivot;

        pivot = delimiterLocations[delimiterLocations.Count - pivot];
    }
    else
    { return source; }

    // reverse the first part
    for (int i = 0, j = pivot - 1; i <= j; i++, j--)
    {
        temp = sourceChars[i];
        sourceChars[i] = sourceChars[j];
        sourceChars[j] = temp;
    }

    // reverse the second part
    for (int i = pivot + 1, j = sourceChars.Length - 1;
         i <= j; i++, j--)
    {
        temp = sourceChars[i];
        sourceChars[i] = sourceChars[j];
        sourceChars[j] = temp;
    }

    return new string(sourceChars);
}

Someone asked the following question on StackOverflow. Before I could post my answer, it was removed. Hmm, so He/She tried to abuse StackOverflow! Anyway, I found that question interesting.

The question was to write a function to rotate a string of words. Words are separated by ‘ ‘ (space). In the result string, the words should remain human readable. The function will also take an integer argument that will specify number of words to rotate.

example:

string source = “A quick brown fox jumps over the lazy dog.”

rotateString(source, 3);

Should give:

the lazy dog. A quick brown fox jumps over

Here is my solution:

static string rotateString(string source, int rotationCount)
{
    if (String.IsNullOrEmpty(source) || rotationCount <= 0)
        return source;

    int pivot = 0;
    List<int> delimiterLocations = new List<int>();
    char[] sourceChars = new char;

    char temp;
    // Reverse the whole string and
    // save the dilimiter locations
    for (int i = 0; i < source.Length; i++)
    {
        sourceChars = source[i];

        if (delimiterLocations.Count < rotationCount && source[i] == ' ')
            delimiterLocations.Add(source.Length - i - 1);

    }

    // calculate neededDelimiters mod wordCount
    // (assume words = delimiterCount + 1)
    pivot = rotationCount % (delimiterLocations.Count + 1);

    if (pivot > 0)
        pivot = delimiterLocations[pivot-1];
    else
        return source;

    // reverse the first part
    for (int i = 0, j = pivot - 1; i <= j; i++, j--)
    {
        temp = sourceChars[i];
        sourceChars[i] = sourceChars[j];
        sourceChars[j] = temp;
    }

    // reverse the second part
    for (int i = pivot + 1, j = sourceChars.Length - 1;
         i <= j; i++, j--)
    {
        temp = sourceChars[i];
        sourceChars[i] = sourceChars[j];
        sourceChars[j] = temp;
    }

    return new string(sourceChars);
}

My laptop usually got very hot and CPU and GPU idle temperatures were in the range of ~75C and ~80C respectively. Its about eight months I bought my laptop and I finally decided to open it up and apply thermal paste to both CPU and GPU.

Getting to the CPU was fairly simple just remove 2+4 screws and apply the thermal paste.

But, getting to the GPU was real pain. So, I decided to write a post to describe it in simple steps and gotchas that I discovered.

Disclaimer: Opening and applying thermal paste to CPU or GPU will void your laptop’s warranty! Author assumes absolutely no liability for these opinions nor for any damages that may result from reading and/or implementing following steps.

Before starting anything, unplug the power and remove the battery.

1. Remove the keyboard. For this remove the two screws that are labeled ‘K’ from the under side of the laptop, then using a small flat(slotted) screw driver, un-clip three plastic holders at the top edge of the keyboard . Then tilt it over and unplug two flat cables and one connector with wires grouped together.

2. Then remove the covers of the ram and the hard drive compartment. Carefully remove the rams modules and hard drive and keep it a side. If you haven’t removed CPU compartment cover do it now.
* In the CPU compartment, there is a screw hidden just between the heat sink exhaust and the edge of the laptop. The is covered by the aluminum foil so you have to peel it to remove it.
* Also don’t forget to remove a screw just beneath the hard drive!

3. Remove 3-4 tiny steel screws from the battery compartment. Then remove the rest of the screws from the laptop base. Also remove six screws from the under side of the hinges. Two hinge covers will come off.

4. Remove screws from backside and remove the lid covering the LCD cables. Carefully remove two screws under this lid. Then unplug the two connectors.

5. Tilt screen to the max and remove two long screws that hold the LCD panel in the grooves. Carefully remove the LCD panel and keep it aside.

6. Now slowly lift the upper cover. It should come off w/o problem. You’ll get a first look at the motherboard. But you still don’t see the GPU!!!

7. You have to remove couple more screws and unplug speaker cables and the DVD drive. And volia! you can lift the motherboard and turn it over. And there you’ll see the other heat sink.

8. Go ahead and remove the screws from the GPU heat sink, unplug the fan power connector and carefully detach the heatsink. You’ll see that the underside of the GPU heat sink has a thin aluminum foil that according to me prevents thermal paste short circuiting the connectors on the GPU. There is another reason for doing it this way. During laptop assembly the person gets hardly few minutes to apply the paste and set the heatsink, it is easy to just use the foil to cover the die and apply paste and slap the sink on to it – quick and dirty huh? But as I told earlier it does prevents thermal paste spreading over the GPU circuitry around the die!

9. Remove the foil and the thermal paste. Observe how excessive paste was used! I used a plastic card to get rid of it and finally cleaned it up with some 90% isopropyl alcohol (picked it from local Wallgreens for $2) and cotton swabs. The copper heat sink was now smooth and clean like a mirror. The die should be clean as new – but just to make sure clean it as well using a new cotton swab and alcohol.

Msistuff.exe and Setup.exe are two important binaries are needed to create MSI bootstraper. Unfortunately you need to download the whole Windows SDK to access these binaries.

Fortunately there are pre-built msistuff.exe and setup.exe binaries available from WIX examples page:

http://sourceforge.net/tracker/?group_id=105970&atid=654188

Download the Bootstraper example from this page.

To open command prompt with administrator privileges by right clicking on a directory in windows explorer: copy the following text and save it in a file with extension .reg. Then right click it and select merge.

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\Directory\shell\runas]
@=”Open Admin Command prompt Here”

[HKEY_CLASSES_ROOT\Directory\shell\runas\command]
@=”cmd.exe /s /k pushd \”%V\”"

Similarly if you need to open Visiual Studio 2008 command prompt with elevated permissions in Vista use this to create the registry file:

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\Directory\shell\runas]

@=”Elevated VS 2008 Command Prompt”

[HKEY_CLASSES_ROOT\Directory\shell\runas\command]

@=”cmd.exe /s /k pushd \”%V\” && \”C:\Program Files\Microsoft Visual Studio 9.0\Common7\Tools\vsvars32.bat\”"

I use gentoo linux on my laptop (G1S-A1). Everything is working including wireless, bluetooth, media keys etc.
The only thing that annoys me is when I use skype beta (with video) or any other webcam utility. The webcam image is 180° inverted!! I know it sounds funny..but its annoying after a while… Anyway, as usual I set out on the quest to find out the cause and possible remedy. A quick lsusb gives tells me that the device id and vendor id information.

localhost ~# lsusb
Bus 002 Device 001: ID 0000:0000
Bus 007 Device 002: ID 0b05:1712 ASUSTek Computer, Inc.
Bus 007 Device 001: ID 0000:0000
Bus 006 Device 001: ID 0000:0000
Bus 005 Device 002: ID 046d:c521 Logitech, Inc.
Bus 005 Device 001: ID 0000:0000
Bus 001 Device 003: ID 0b05:1726 ASUSTek Computer, Inc.
Bus 001 Device 002: ID 174f:5a35
Bus 001 Device 001: ID 0000:0000
Bus 004 Device 001: ID 0000:0000
Bus 003 Device 001: ID 0000:0000

To get more information about the webcam from vendor/device id

localhost ~ # lsusb -v -d 174f:5a35
…
iManufacturer 2 Sonix Technology Co., Ltd.
iProduct 1 USB 2.0 Camera
…

I tried to google the combination of device id and sonix to find any information about the camera. But it turned out that there is no such device manufactured/assembled by Sonix. I was curious and I thought lets see what the windows driver for this webcam has to say. I rebooted into Vista and bingo! the device information clearly mentions D-Max/Sonix 1.3M pixel camera. All the description regarding their camera modules can be found their website. Two weeks ago I was able to find the module along with device id mentioned. Unfortunately today I’m unable to locate the 5A35 module on that page because all the camera modules have generic names now(e.g 1.3M_UVC 5). I couldn’t find any cached page on google either. Looks like they D-Max doesn’t want to disclose that information.

On further digging through windows driver files, snp2uvc.inf (version 04/18/2007, 6.21.70.001) reveals some cool information.

[SN.NTx86.5.1]
;1.3M
%SN.USBVideo.DeviceDesc% = SN.USBVideo.XP,USB\VID_174f&PID_5a35 ;GD-5A35A(Ov9655)
%SN.USBVideo.DeviceDesc% = SN.USBVideo.XP,USB\VID_174f&PID_5a31 ;GD-5A31A(MI1320)
;2M
%SN.USBVideo2M.DeviceDesc% = SN.USBVideo2M.XP,USB\VID_174f&PID_5a51 ;GD-5A51A
;VGA
%SN.USBVideoVGA.DeviceDesc% = SN.USBVideoVGA.XP,USB\VID_174f&PID_5a11 ;GD-5A11A(Ov7670)

Hmm…After searching for GD-5A35A I found this cached link that links 5A35 to the generic model number that is 1.3M_UVC 1. So, here are the specifications:

1.3M_UVC 1 USB 2.0 1.3MP Camera Module Support UVC

SPECIFICATION:

• SXGA Resolution Image Sensor
•Video Resolution:
1280 x 1024, 1280 x 800
1204 x 768, 800 x 600
640 x 480, 352 x 288
320 x 240.
•Frame Rate:
640 x 480 at 30fps maximum
1280 x 1024 at 8fps maximum
•Video Format: YUY2
•LED Indicator
•DOF on 30~80cm
•Support UVC
•Auto Exposure
•Auto White Balance Control
•High Speed USB 2.0 Interface
•Low Power Consumption
•RoHS Compliant
•Dimension(LxWxH) 60 x 8.5 x 7.05mm

On careful inspection of snp2uvc.inf you can see that my webcam uses OV9655 sensor – cool! And the datasheet for that can be found here: http://rapidshare.com/files/94672360/OV9655-datasheet.pdf.html

Interestingly the newer version of the webcam driver doesn’t specify the sensor (OV9655) or the model number (GD-5A35A) information.

Most of the datasheet information went over my head except some interesting bits.
If you skip to “Register Set” and checkout register 1E :

1E MVFP 00 RW  Mirror / Vertical Flip Enable                

Bit[7:6] Reserved
Bit[5]   Mirror
    0: Normal Image
    1: Mirror Image
Bit[4]   Vertical Flip
    0: Vertical Flip Disable
    1: Vertical Flip Enable
Bit[3:0] Reserved

Default value for bit[4] is 0, i.e VFlip is disabled. We get upside down image which means that the webcam module is installed upside down on G1S-A1, so the linux uvc driver must find a way to set the bit[4] of this register.

I’m reading through uvc-linux source to understand the driver and make appropriate changes. But it can take sometime… Sole purpose of this blog entry is to inform you guys about my findings, so someone with the right knowledge can add the vflip support for this webcam.