timeBeginPeriod

Was reading how the use of timeBeginPeriod to increase system tick frequency could lead to a shorter battery life (read here) ...decided to investigate how timeBeginPeriod function interacts with Windows 8, since Windows 8 uses tickless kernel and theoretically has no relations with system timer ticks. From MSDN, timeBeginPeriod resides in winmm.dll. There are 2 versions on winmm.dll on my Win 8 machine, one under c:\Windows\SysWow64 and one under c:\Windows\system32.

timeBeginPeriod in c:\Windows\SysWow64\winmm.dll:

timeBeginPeriod calls an imported function, timeBeginPeriod@4

timeBeginPeriod@4 belongs to api-ms-win-mm-time-l1-1-0.dll

timeBeginPeriod@4 in api-ms-win-mm-time-l1-1-0.dll is an empty function

timeBeginPeriod in c:\Windows\system32\winmm.dll uses the same flow, importing the function timeBeginPeriod@4 from api-ms-win-mm-time-l1-1-0.dll:

x64 api-ms-win-mm-time-l1-1-0.dll uses the same function for multiple exports

And that one function is empty

Hence, I've verified that timeBeginPeriod does not work in Win 8...so why is Win 8 battery life still so weak?!

How Procmon works

Out of curiosity I looked under the hood of the tool that lets you look under the hood of other programs.

To be able to monitor so many system functions at once, Procmon probably uses a driver to do that. So I went looking for Procmon's driver using GMER, and found PROCMON23.SYS.

I didn't see PROCMON23.SYS inside the Sysinternals directory, so I guess it'll be inside the PE structure. Sure enough, when I use PE Explorer to open up Procmon, I found it inside the BINRES directory in the RESOURCE section.

Extracted out the driver, and analysed using NikPEViewer. It's a 32 bit driver.

Then proceeded to analysis using IDA. It registers itself as a filter driver...

Creates a filter communication port at \ProcessMonitor23Port and starts the filter.

Procmon 64 bit

When running Procmon in 64-bit systems, another process called Procmon64.exe is created. This isn't found anywhere in the Sysinternals folder.

Procmon in 64-bit Windows

This implies that its 64-bit image is being stored in its 32-bit executable. Hence, I looked up the second entry under the BINRES section, and sure enough, it's a PE file:

Location of Procmon 64 bit image

Procmon's 64 bit image

Initially I thought it was the 64-bit Procmon driver...turned out that it is the 64-bit Procmon executable. And of course, the 64-bit driver is hidden inside the 64 bit executable's resource section.

Procmon 64 bit driver

How to turn off monitor screen

Found a small program called Turn Off Monitor, decided to investigate how it works.

 Used IDA to open it, turned out to be a .NET exe. Opened it using Dotnet IL Editor instead.

Main code:


Seems like the only API call needed is SendMessage. ldc.i4.m1 means push -1 to stack, so the API call is SendMessage(-1,a,b,2).

SendMessage belongs to user32.dll:


Second argument, a is 0x04000003:


Third argument, b is 0x04000004:


So the only API call needed turned out to be user32!SendMessage(-1,0x04000003,0x04000004,2).

Kindle digital photo frame part 5: testing and finalizing

The scripting and programming is mostly complete. Time to test the Kindle. For the purpose of testing, I set the Kindle to change screensavers every 5 minutes instead of every 3 hours. It works flawlessly for hours at a time, then fails. It always fails in the same way: displaying no picture in screensaver mode. Even manually pressing the button power twice does not solve it. Perhaps the Blanket program crashed or something, I don't know, but it fixes itself after a restart.

After hours of debugging I still cannot figure out what the problem is. Decided to call it quits, but added a recovery option should that happen. I installed KUAL and kterm, so that after a reboot I can manually run my screensaver changing script again.

Finally, I decided to consolidate both the script to change screensavers and that to download images. Here's the final masterpiece:

I've reset the screensavers to change every 3 hours instead of 5 minutes. It'll still be a few days before I present this to my girlfriend, a final few days to test and make sure it works perfect!

Kindle digital photo frame part 4: downloading pictures from the net + more screensaver problems

Even more problems came to bite me. I had intended to use wget with some options like -r to easily download all the images that I have listed on the front page of my CakePHP backend. However, Kindle's busybox wget is quite primitive; it does not have so many options, and I am forced to perform grep, awk and a lot more scripting to download the pictures that I uploaded. Here's the code:

In addition, Kindle renames screensavers after restart. All the photos inside the screensavers folder will be renamed to bg_xsmall_ssXX.png. That implies that a maximum of 100 photos are allowed. In addition, if the order of the photos is to be randomized via creating a file called "random", all the photos' filenames will be randomized again upon bootup, meaning I won't be able to tell if /var/local/blanket/screensaver/last_ss points to a photo or downloaded image.

In view of these, I decided to rotate the photos myself by placing one 1 photo inside the screensavers directory: bg_small_ss00.png, and replace that file everytime I change my screensaver. As usual, Busybox is so limited in functionality that I have to go through massive scripting just to choose a random photo or determine a random number. This is my updated screensaver-changing script:

MK 809 III Android mini PC

The MK 809 looks like an oversized thumb drive that plugs into a HDMI port, but it is a full fledged android pc. I was quite excited when I saw it on sale on Qoo10; I've been wanting a powerful arm computer to test BOINC on, and the MK 809 III has 4 cores, fits into my palm and uses a phone charger. Sweet!

I'm more bitter about the price though. The Qoo10 seller was selling at S$96 including shipping fees. That's out of my budget. Decided to source upstream, and found it alibaba.com, selling for US$45 a piece. However, there is a minimum order of 10. Thus finally, I went to it's sister site, aliexpress, and found one selling at US$57. Perfect!

I wonder if an Android OS can be used for programming?

Would update when the item arrives.

Final Fantasy Fables: Chocobo's Dungeon

Just cleared the 100 levels dungeon in Chopin's dungeon for the Wii. I killed the boss at level 71, and was level 8 dragoon wearing a genji's  talon+79 and king's saddle+57 when I did it. All I did was spam Holy Lance and Gungnir, drink ethers like crazy, and ate just one Phoenix down when near death.

Phew, that was fast!