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[Issue] event call notify at the same time


DS1701
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Hello @all

Description:

I have 2 input port sc_in<Data> input[2];

2 method "HandleInput(int port_index)" (using sc_spawn) with sensitive is input port

1 method "MainProcess"

"HandleInput" method will trigger "MainProcess" with main_process_event.notify(SC_ZERO_TIME)

Symptom :

"HandleInput" is called 2 times ( port_index = 0 and 1) at the same time (It is called before "MainProcess" is called )

"MainProcess" is called 2 times -> This is not desirable, My expected is "MainProcess" is called 1 time

I tried to reproduce it with the simple code ( as my attached), but I can't

As my check:

1. "HandleInput" with port index = 0 is called -> main_process_event.notify(SC_ZERO_TIME) is called -> m_notify_type = DELTA -> sc_event::trigger() is called

2. "HandleInput" with port index = 1 is called -> main_process_event.notify(SC_ZERO_TIME) is called ....

Because at (1) sc_event::trigger() is called => m_notify_type = NONE => So, at (2), when  main_process_event.notify(SC_ZERO_TIME) is called, kernel add new delta event => MainProcess triggered 2 times   

But I don't know why at(1) sc_event::trigger() is called ?, I think (1) and (2)  are same phase (Evaluate), I don't know this is a systemc bug or not?
Could you please to support?
BRs

DUT.cpp main.cpp

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Hello @DS1701,

It is difficult to understand from the information you have posted on what you want to achieve.

Can you please share complete source code and terminal output from the said program?

And, possibly what actually you feel should be the output.

Regards,

Ameya Vikram Singh

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  • DS1701 changed the title to [Issue] event call notify at the same time

Your understanding is correct: if a process (MainProcess in your case) is waiting on an event (main_process_event) that is notified twice in two different processes that are part of the same eval phase (using delta notification), then the process will be triggered only once - in the next evaluation phase.

In general, an event will have only one pending notification. The details are in "5.10.8 Multiple event notifications".

So, you have to debug your original code - to find out why MainProcess is getting triggered twice. In addition to sc_time_stamp(), you can also print sc_delta_count() - to check which delta cycle the event notification is being done (and which delta cycle the process is getting triggered).

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