Lpc2000

Thanks to all!

This sounds good, but what about Richard's problem concerning file names
which are not 8.3 compliant? Is there a problem with this docs?

  Sten

Dan Beadle wrote:
> When you delete an entry in the DIR by writing E5 to the first byte, you
> must first deallocate all used sectors. 
> 
>  
> 
> (If you don't, you have to old DOS problem of lost clusters)
> 
>  
> 
> Delete File:
> 
>             Starting at First Cluster,  (from Dir entry)
> 
>                         Walk through the cluster allocation table,
> unlinking each cluster from the file (returning to free) 
> 
>             Then mark first byte of file name to E5.
> 
>  
> 
>  
> 
> As for writing, it is just the reverse...
> 
>  
> 
> Make sure the files does not exist, if it does, delete it per above.
> 
>  
> 
> Search the directory for an entry starting in NULL or 0xE5 (previously
> deleted)
> 
> Fill in your information in that structure. (File names are fixed size,
> not null terminated. Pad with blanks)
> 
> Find a free cluster from the Cluster Allocation Table. 
> 
> Put that entry into the Dir. 
> 
> Mark that cluster as EOF (FFFF) in the CAT
> 
> Write the first cluster of information.  
> 
> If there is more, find another free cluster
> 
>             Mark the new cluster as EOF in the Cat
> 
>             Change the EOF on the prior cluster from EOF to point to
> this cluster
> 
>  
> 
> Repeat till end of file...
> 
> Update the directory structure with file size, time (if desired).
> 
>  
> 
>   _____  
> 
> From: lpc2000@yahoogroups.com [mailto:lpc2000@yahoogroups.com] On Behalf
> Of rtstofer
> Sent: Thursday, November 10, 2005 12:15 PM
> To: lpc2000@yahoogroups.com
> Subject: [lpc2000] Re: Cheap SD Flash File System
> 
>  
> 
> --- In lpc2000@yahoogroups.com, "Joel Winarske" <joelw@i...> wrote:
> 
>>>>does somebody have some good documentations about FAT12/16/32? 
> 
> (And
> 
>>>>would share it?) ;-)
>>>
>>>
>>>http://www.ntfs.com/fat-systems.htm
>>
>>Also:
>>
>>http://www.microsoft.com/whdc/system/platform/firmware/fatgen.mspx
>>
>>
>>Joel
>>
> 
> 
> I just ported the FAT32 file system stuff from WinAVR to ARM.  I 
> used both of the references above and, at the moment, I can read and 
> follow the chains of files created by WinXP.  The files don't have 
> to be defragged but, as a limitation, I only use the short file name.
> 
> Neither of those specs deals with the issue of creating a file.  Do 
> you just go look for a deleted file and use all of its' allocation 
> until you need more?  Since you only have the single directory 
> entry, how do you grab allocation units away from other deleted 
> files?  How do you find an empty allocation unit in the FAT?  How do 
> you insure that you are building a proper short file name from a 
> long one, and vice versa.  In FAT32, both are required and the 
> directory entries must be contiguous.
> 
> There are HUGE holes in both of those docs.  So, for my MP3 player, 
> I can only read files based on 8.3 names.  Not a good situation.
> 
> I really want a writable configuration file that will tell the 
> player how to deal with serial commands, telnet commands and the 
> hardware inputs/outputs.  At a minimum, I need to tie a file name to 
> an input pin so an effect file will play if a sensor is tripped.  I 
> would like to do the configuration interactively via serial or 
> telnet but, as I can't open a file for writing, that isn't 
> happening, yet...  It's on back burner until I get the ethernet 
> stuff integrated with the CF and MP3 - maybe next week.
> 
> Richard
> 
> 
> 
> 
> 
> 
> 
> 
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-- 
/************************************************
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