Killing time with a smile in BUS (with PythonS60 programming on my Mobile ;-)
Topic: Me
This weekend had been to bijapur in sleeper bus. Now to kill the time when awake in the bus, I looked up some of the Python S60 sample scripts I had installed with the PyS60 in my symbian mobile phone some days back. Figured out the abc... of python and some of its features in symbian AND updated the sample recording script more to my liking with support for amr recording (well just change the extension ;-) and option to key in or select a set of predefined filenames.

Finally I could use the mobile more as a live programming device, to experiment quickly or rather in this case develop/customize a logic/functionality that was lacking in the mobile by default. Thats what I had hoped to do on hearing about this python stuff for symbian supported by nokia and here I was doing it in the bus, in the process learning python, bit of symbian and also killing time with a smile ;-)

MEDC2006 - WinXPembedded and others
Topic: Technology
Was busy after the MEDC2006 i.e to office after 3 days so didn't get time to update earlier

On 2nd day attended the WinXP embedded track to see what it was all about. As it turns out WinXPEmbedded is nothing but componentized WinXP which is normally used in ones PC. Currently only binary modules are provided by MS and that too only for the x86 architecture. As far as drivers are concerned standard PC drivers can be used in WinXPe. Even thou MS seems to have WinXPe for other architectures (powerpc for sure, well almost, why? because Xbox360) internally they aren't giving it to others.

As of now because of lack of support (atleast outside MS) for NonX86 architectures, Relatively large size of resultant WinXPe images (unless MS allows one to build up the GUI and other standard functionalities at the higher level as one likes) and lack of source code support would make it a difficult candidate to use in the embedded world.

One thing I liked about the MEDC2006 india was that it allowed the people who attended the conference to interact with the key speakers and also arranged hands-on tracks inturn handled by these key speakers.

Day One at MEDC2006 - J2ME vs .NETCF, WinCE memory architecture, Arm Emulator and NMD Feature pack
Mood:  down
Topic: Technology
Today I attended the MEDC2006 conference being held at Bangalore. Overall it was ok. Came to know some of the inner working of WinCE, hadn't found time before to look into this :-).

Started with attending a talk comparing WinMobile and Symbian mainly from their virtual execution env (i.e J2ME vs .NETCF). Even thou it was good in some ways, it was too marketing pitch based as far as talking about J2ME was concerned, trying to tell that it is a bunch of headache to develop anything 4 J2ME. Only forgetting that MIDP1 is pretty old (well for that matter even MIDP2) and was targeted to run on realy really resource constrained phones which where available long long time back. And .NETCF would be pretty difficult to run in such a h/w with all its features. So telling that there is MIDP1 and MIDP2 for people to worry about is wrong, for sometime now most of the phones out there support MIDP2. Similarly telling that MIDP2 doesn't need to support Float if you look at the suggestions in the standard, when in reality most of the MIDP2 phones out there would be supporting CLDC1.1 which supports it. And many such ...

Then I attend many of the WinCE internals talks. Which was interesting. Starting with their threading and schedular logic which is some what similar to the realtime threading mechanism in linux(well almost except that almost everything is a thread in wince, which is good in some sense AND chances are even linux will have a slightly better and flexible concept of some threads with priority above some int't handler threads (or any mix and match) by default (currenlty requires to be manually patched at int't subsystem level AND or some other hacks)).

However wrt their Memory management and architecture, I found it strange that the developers didn't try to add support for making the applications position independent by supporting address fixup support at application startup time, well you ask why should they have, then continue reading. It seems WinCE maintains 31 slots (each 32MB in size) in the lower part of the processor virtual memory space for applications thus only 31 (well seems like 29-30) applications can be running in the system at any time. And inturn it always maps the current application to run in a 64MB window (i.e 2 slots) at the bottom, of which the lower slot (i.e 0) holding the application (code, data, heap and stack) space along with Non rom dlls AND the slot 1 holding the core and ROM based dlls. Thus when ever any thread in the system has to run the lower vaddr entries in the system pagetable are patched such that application slot (to which that thread belongs) is also mapped into the 0th slot. Even thou the page table updation required at context switch might be minimal the TLB will require to be flushed of any slot0 related virtual address mappings as they will be remapped to the memory maps for the switched into application. _By_ _letting_ the DLLs remain at a fixed slot(s) in memory across all processes (as is done even now) _AND_ by letting the application remain in its alloted slot (i.e 2-31) (and if required don't map any dll to this space, but to slot 1 and if required slot 0) and not mapping it into slot 0 the need for these TLB flushes and subsequent TLB updation (well almost, depends on dynamics of the system) can be avoided AND also the pagetable fixup required will/should also be relatively minimal.
Hope they either follow some scheme like what I mentioned above (or similar, where the number of lower slots alloted to DLLs is dynamically adjusted based on the need in the system in addition to what I mentioned above or ...) OR move fully away from the slot based management system in their new/coming versions of WinCE (well may be not really this drastic).

Also found that now they have a ARM based wince device emulator, freely downloadable have to check this out.
Today they have announced the availability of NetworkMediaDevice (NMD) Feature pack 4 wince, but the sad part from my perspective atleast is that they have not used their existing RTC framework to add this functionality but have implemented it over a new framework involving uPNP, WebServices, HTTP streaming and their DRM for streaming.

My first blog posting
Mood:  lazy
After a long time I decided to get on the web and check out things just for the fun of it. However that sucked me in to check out status of some emulators which I keep dabling with once in a while. Which inturn led to me going to Mips site and downloading their documents on Mip32/64 architectures (by the way I had done a port of linux (and development of a linux based internet ready settopbox) to a Mpeg2 decoder chip from LSI which used Mips core around 6 years back, my first attempt at Linux porting then). Which inturn led to linux-mips.org site and a indirect link to a old article by me from that site. Also I noticed the Mips emulator I had used to experiment long back MipsSim Java in a almost orphanned stage. As I had done some modifications and enhancements to it back then (as usual hadn't found time to post it back to net), thought I should recheck its still ok and put it back on the net.

This reminded me of my homepage at tripod. On checking out found that the good guys at tripod/lycos had still kept it active. Thanks guys. Cann't say same about my domain name from Namezero, I know partly I am to be blamed for having not read their email about moving domain manager/??? authority around to them (as usual I hadn't read the emails for a long long time, and why should have I, I had paid them for was it 5years, and as worse as it can get I realized that my domain was in limbo just a month after the was it 5 or was it 3years term). And off I was searching for my homepages saved in their pristine form (no ads etc added by tripod) somewhere in my hdd, and dug them up using locate (those kiss programs from unix/linux ;-) and my structured storing habit on disk (which I again do in those once in a bluemoon bouts).

And realized that I hadn't updated my webpages for almost 3 years. So updated the frontpage with some of the new things that happened at work front. And thats when I noticed this blog support from tripod, didn't think much about it yesterday, but today while killing some time in the evening decided let me give it a try and here I am with my first blog post.