[ECOS] Share RAM resource help

Oscar martinos72@libero.it
Mon Apr 5 01:58:00 GMT 2004


I'm working with ecos+microwindows on xscale PXA255 and i need:
1. improve built in LCD controller (i need to drive lcd bigger then 
640x480) adding external logic for manage the frame buffer refresh 
outside from the cpu's databus to avoid bus overhead
2. add an external video source that it'll share the LCD with ECOS.
So i need to share the RAM frame buffer beetween CPU (microwindows 
thread), hardware LCD refresh (hardware1 thread that only needs to read 
from the fb) and second external video source (hardware2 thread that 
only needs to write to the fb): i've one sw thread and two hw threads. 
The hardware threads always need to finish the own execution before 
being interrupt.
To resolve this problem i thought to manage the hw threads by sw threads 
give to ecos the necessary input/output signal for manage the hw (ex. 
request_resource_from_hw and hw_finish_thread_execution) and use ECOS 
mutex facilietes for manage the RAM sharing.
Could be this a good way to face the problem? Have anyone another idea 
or recommendation?
I can't understand where is the best point in MW source code to put the 
CYG_MUTEX_LOCK, i think just before the frame buffer call.... but where? 
In wich file?
Thanks
OSCAR 
     



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