Results 1 to 5 of 5

Thread: Programming applications w/EWF enabled

  1. #1
    FLAC IntellaWorks's Avatar
    Join Date
    Jun 2004
    Location
    NH
    Posts
    1,173

    Programming applications w/EWF enabled

    Hello, I fig'd I start a thread for programmers who are developing applications that will be running w/ EWF enabled. Since I have some questions that some of you may already know this would be a great place to ask/anwser some known facts about EWF..



    Here's a question:

    I'm developing a front end that will actually be running as a shell to windows instead of windows "explorer" I'm also developing my application to run on a CF converted to IDE meduim. Since we all know that the faster CF cards cannot have multiple partitions (Extreme III for example) everything must be run from one partition. The problem I am finding lies with only haveing one partition, with EWF protecting the entire partition how can my application/front end write new information to a database ?

    My original thinking was to store the database onto a removeable drive and point my application to the removeable drive (which wouldnt be protected and writes would be allowed) but what if I forget that removeable drive (most likely it would be a laptop drive that would store all my media + the database)

    I'd still want my front end to have basic functionality, (play CD's, DVD's look at GPS) The problem with this lies in the code itself... You'd almost have to program two methods of gathering music and it seems a bit redundant anyone have suggestions ??


    Here's what I've come up with thus far... Since my Mobo has onboard CF I could get another smaller CF card (that can withstand the same temps that my OS CF card can withstand and store the DB on that card...
    Progress [I will seriously never be done!]
    Via EPIA MII
    512MB RAM
    OEM GPS (embedded)
    nLite WinXP pro on
    1GB Extreme III CF card
    Carnetix 1260 startup/ DC-DC regulator
    Software: Still, re-Writing my existing front end in .Net

  2. #2
    FLAC SFiorito's Avatar
    Join Date
    May 2004
    Posts
    1,365
    Well, if all you need to do is play CD's, DVD's, radio, XM why do you need to write to the partition or read the database? Actually... even when you're playing mp3s and video files what really do you need to write? The only time I would imagine you need to write anything is if you're adding information: new songs, new videos, adding info to GPS for hotspots and such. My system will just assume if no removable drive is present simply startup the default function (radio or XM on a default channel I choose). I've also been thinking that it may be possible to have a restart file saved between reboots. EWF has a function to commit a specific file without disabling EWF, but the file cannot change in size otherwise you could screw up your partition. I was thinking of making a file format that will be real basic for storing the last function. Something like:

    Code:
    <radio on=0 laststation=097.9>
    <dvd on=0 lastpos=00:23:34>
    <xm on=1 laststation=XXX> <!-- not sure how XM stations are stored -->
    ....and so on. This is just an example, but you see where I'm going? Basically you would have to make sure the filesize never changes, but can still store data in it. So this restart file will always be present on the CF card, but if there are no other drives then you disable the mp3/mpeg file browser. I don't think it'd be that much overhead to make these changes.

    *EDIT*: Also, why not store the DB on the card, if you've got the space? As long as you don't need to write to the DB EWF won't be a problem, but let's say you add some data to your system: add it to the removable drive, insert meta info in the DB, tell EWF to commit the data on next reboot (ewfmgr c: -commit or you could use the EWF API). Then when you shut off your car, EWF will commit the data when XP shutsdown. Start your car back up again and EWF will still be enabled, but your database will now be updated.

  3. #3
    FLAC IntellaWorks's Avatar
    Join Date
    Jun 2004
    Location
    NH
    Posts
    1,173

    .

    Well, my front end is using the DB as a very central component. Ie, last song you played, new songs.. voice reco strings, setings...

    Also my front end will automatically download new music from a server-app, and there fore the DB will need to be updated.

    I had a feeling EWF had a function that enabled 1 file to be able to retain its information... but unfortunitly this system and my designs thus far just don't mix. I suppose if I re-designed some things this would be useful...


    Here is what I've come up with. (I'm going to get another CF card and insert it into the built in CF slot, this card will hold the DB and be volitile... Also as an added function this secondary CF card will be a holding place for newly downloaded music, when the system recognizes that the true removeable media drive is available it will move the new songs over from the CF to the removeable drive... I think this system will give me the felxibility I need, plus have storage that can withstand extreme temps safely..

    I was thinking a 256MB Extreme card (if I can find one)



    Another question: Does EWF throw away the writes or does it store it into memmory so that the data can be used until the system is powered down ??
    Progress [I will seriously never be done!]
    Via EPIA MII
    512MB RAM
    OEM GPS (embedded)
    nLite WinXP pro on
    1GB Extreme III CF card
    Carnetix 1260 startup/ DC-DC regulator
    Software: Still, re-Writing my existing front end in .Net

  4. #4
    FLAC SFiorito's Avatar
    Join Date
    May 2004
    Posts
    1,365
    They're kept in memory and either flushed or committed on shutdown. You could get an UltraII or ExtremeI card and partition it so one partition is protected and the other is not for the database. Only problem is if you're doing heavy writing to the CF disk it'll eventually die.

  5. #5
    Nic
    Nic is offline
    FLAC Nic's Avatar
    Join Date
    Oct 2003
    Location
    Melbourne, Australia
    Posts
    1,047
    why dont u use 2 databases, one for voice commands, settings etc which is stored on the cf card (tell me your gonna change this stuff often), and one on the removable drive for your music info, last song playing etc. If the removable drive isnt present just have it default to a main menu or something. Thats what i'd do at least
    Signature: [==||========] 20% complete

Similar Threads

  1. Add Applications - Applications Screen
    By frodobaggins in forum FP FAQ
    Replies: 0
    Last Post: 12-01-2004, 05:38 PM
  2. Wanting to learn some programming, help me pick a language!
    By RS3RS in forum Software & Software Development
    Replies: 32
    Last Post: 10-15-2004, 04:38 PM
  3. C++: GUI Programming with >NET Framework
    By [iG] in forum Software & Software Development
    Replies: 3
    Last Post: 05-24-2004, 06:57 PM
  4. batch file programming LCD's
    By mosh in forum LCD/Display
    Replies: 6
    Last Post: 05-19-2002, 12:55 AM
  5. Need to start somewhere with Hardware programming
    By 168db in forum Software & Software Development
    Replies: 7
    Last Post: 01-11-2002, 08:35 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •