[En-Nut-Discussion] IJG jpeg decompression problem

Curtis Maloney cmaloney at cardgate.net
Thu Jun 12 02:02:58 CEST 2008

steve wrote:
> Hi,
>   I'm trying to use Ethernut (on a SAM7X256-EK) with IJG's jpeg
>   decompression code (ijg.org).  It kind of works but the process of
>   decompressing a very small 16x16 pixel test image, which does generate
>   the correct output, screws up NutNet in such a way that any subsequent
>   call to NutUdpReceiveFrom or NutUdpSendTo immediately crashes
>   the processor without an error message.  At the point just prior
>   to crashing NutHeapAvailable() reports 27KB of free memory.
>   I wonder if anyone else has attempted to use the IJG code or can
>   give me some pointers on what might be going wrong.  I'm new to
>   Ethernut and the Yagarto Tools and am inexperienced in C
>   programming so please be gentle.

We used it for another project, on a different board, but what I can tell 
you is it's highly inefficient IFF you have the whole JPEG on hand to work 
from.  It's written to deal with slow incoming streams, being fed the data 
as they arrive.

It would be much simpler, lighter code if it knew it had all the data on 
hand.  And, I dare say, would do a lot less messing about with de/allocating 

Curtis Maloney
cmaloney at cardgate.net

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