RE: [ECOS] ISR+thread synchronization problem

[Schmidt Henning Larsen <HenningLS at danfoss dot com>]

Hi.

I've made myself a generic buffer that I use everytime I have to get data
from ISR to thread.

Any comments to the code are welcome.


Henning



#include "include/cyg/kernel/kapi.h"
/*
  irquffer is a fifo-buffer, that can be used to send data from a ISR to a
thread
  can only be used in one to one communication
  Caution: put(T x) must be called from the ISR
           notify() must be called from the DSR
           get() must be called from the thread
*/

template <class T, int size>
class irqbuffer
{
 private:
   T arr[size];
   int fsize, inn, out,fmax;
   cyg_sem_t seEmpty;
 public:

   irqbuffer(); 
   
   ~irqbuffer();

   void put(T x);

   void notify();

   T get();
};


template<class T, int size>
irqbuffer<T, size>::irqbuffer():fsize(0), fmax(size)
{
   cyg_semaphore_init(&seEmpty, 0);
   inn=out=0;
}



template<class T, int size>
irqbuffer<T, size>::~irqbuffer()
{
//   NOP;
}


template<class T, int size>
void irqbuffer<T, size>::put(T x)
{
   // If full then there perhaps should be som handling
   arr[inn++]=x;
   inn %= fmax;
   ++fsize; 
}

template<class T, int size>
void irqbuffer<T, size>::notify()
{
   cyg_semaphore_post(&seEmpty);
}


template<class T, int size>
T irqbuffer<T, size>::get()
{
   cyg_semaphore_wait(&seEmpty);
   T result = arr[out++];
   out %= fmax;
   --fsize;
   return result;
}
  






> -----Original Message-----
> From: jagadisha maiya [mailto:pjmaiya@c4.com]
> Sent: 25. januar 2002 02:25
> To: ecos-discuss@sources.redhat.com
> Subject: [ECOS] ISR+thread synchronization problem
> 
> 
> hi,
> 
> I was reading the mailing list regarding the ISR and thread 
> synchronization problem. In my project also I am  also facing 
> the same problem. But mine is quite strange..
> 
> I am not using DSR.
> 
> ISR uses semaphore to post the event and task uses semaphore 
> wait for receiving the event.
> 
> I am using counting semaphore with inital value '0' to use as 
> a binary semaphore.
> 
> 
> 
> When an ISR post an event through semaphore, the task which 
> waits on the semaphore gets triggered and it services the data. 
> 
> 
> 
> After long time task stops accepting the event and found to 
> be gone for blocking state.
> 
> From there onwards any posting of the event from ISR never 
> invokes the thread. 
> 
> 
> 
> Can U give some suggestion to over come this apart from DSR. 
> Can any body tell me why the task went into blocking state 
> even if it could have been unblocked after receiving  posted events.
> 
> 
> 
> thanx for help, 
> 
> pjmaiya 
> 
> 
> 
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