Bluetooth physiological data acquisition

[Phil Davis]

Hi David,

Here's another approach:

To avoid spending time on file overhead during the data collection period, you 
could collect the data into a variable. Then when data collection is finished, 
write the variable (or put it into a local URL.)

Doing it this way also means the speed of putting the file in whatever location 
you choose is a non-issue.

Of course it could be that the amount of time needed to write to a file is 
negligible. In that case, I would probably use Mark's approach myself, since it 
leaves data on the HD if the app dies during the collection process.

HTH -
Phil Davis



Mark Smith wrote:
> I think I would have script locals to hold the names of source and 
> destination files, and then simply write to the destination file each 
> time new data is read, closing it only when finished:
> 
> local sSourceFile
> local sDestFile
> 
> on run
>   open file sDestFile for update
>   nextUpdate
> end run
> 
> on nextUpdate
>   put char 5 to 8 (or whatever) of URL("file:" &  sSourceFile) into tData
>   write tData to file sDestFile
>   if (your exit condition) then
>     endProcess
>   else
>     send "nextUpdate" to me in 300 milliseconds
>  end if
> end nextUpdate
> 
> on endProcess
>   close file sDestFile
> end endProcess
> 
> 
> You get the idea...
> 
> 
> Best,
> 
> Mark
> 
> On 9 Mar 2007, at 21:22, David Glasgow wrote:
> 
>> I plan to time it all with a 'send doit  to me in tmills milliseconds' 
>> but I go a bit vague beyond that.  Any suggestions about how to do the 
>> read-append as efficiently as possible?   Should I try to read the 
>> specific bytes I want, or read and append the lot, then pick out the 
>> parts I want later?  It may be a dumb question, but if the source file 
>> is in the same directory as the growing destination file, is it 
>> quicker than if the destination file is 'way over there' buried 6 deep 
>> in a different directory?  Does an append get slower the larger the 
>> destination file becomes? Finally, what is the most efficient way of 
>> making the data read conditional?  I had thought about putting a 
>> 'repeat while' somewhere, but I am not sure where.