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hervea

tlm_fifo content safety

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Hi,

 

I am used to making containers with boost::shared_ptr<T> as a data type.

I expected tlm_fifo to have similar semantics to STL containers, such as copy on push (tlm_fifo::put)

But I am seeing a crash at end of sim when the tlm_fifo gets deleted with items still in it, and it looks like the structure under the tlm_fifo (circular_buffer) uses a placement new to allocate a new entry upon write(). This is bypassing the copy semantics of the shared_ptr and creating a wild pointer as a result.

 

First, is this a known problem? If it is, is there another suitable container for shared_ptr?

I basically need a queue with event notification and I'd rather not build my own deque with sc_event's

 

Thank you

Hervé Alexanian

Xilinx, inc.

 

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Which version of SystemC/TLM are you using?  I'm afraid, there is a known issue in the 2.3.1 circular_buffer implementation.  When the fifo is destroyed while there are still elements in it, the loop over the "to-be-cleared" items does not start at the right index.  Instead, you need the following change:

 circular_buffer<T>::clear()
 {
   for( int i=0; i < used(); i++ ) {
-    buf_clear( m_buf, i );
+    buf_clear( m_buf, (m_ri + i) % m_size );
   }
   // ...

In 2.3, there was another indexing bug related to resize, see http://forums.accellera.org/topic/1443-/.

 

Hope that helps,

  Philipp

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