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using an event inside a TCM

LATHEESH

Can we use events inside a TCM.

Can this be implemented as following code:

extend mem{

 handle_memory_access(data,address,word_width)@sys.any is also{

if access == read{

while(TRUE){

sync @sys.top.phase_monitor.data_valid exec{

ad_pairs = cast_to_pair_of_ad(address,data,word_width);

      };

wait cycle;

    };

  };

};

Parents

  • Yes, events are definitely used in TCMs. However it's considered very bad practice to make hierarchical references like your sys.top.phase_monitor.data_valid.This is because you break all the re-use rules, assuming that the phase_monitor will always be located under sys.top an so on. This means your code cannot be reused without modification, and also means that if you have to make any hierarchy changes, you will have to go deep into your code to fix everything that breaks.
    You should instead create a local unit pointer to the phase_monitor, and access the event through the pointer. Here's an example:

     1 <'
     2 unit ph_mon_u {
     3   event data_valid;
     4 };
     5
     6 unit top_u {
     7   phase_monitor : ph_mon_u is instance;
     8 };
     9
    10 unit mem_u {
    11   !p_phase_monitor : ph_mon_u ;
    12   demo()@sys.any is {
    13     sync @p_phase_monitor.data_valid;
    14     wait cycle;
    15   };
    16 };
    17
    18 extend sys {
    19   top : top_u is instance;
    20   mem : mem_u is instance;
    21   connect_pointers() is also {
    22     mem.p_phase_monitor = top.phase_monitor;
    23   };
    24 };
    25 '>

     

    Please also note that if you "wait cycle" on sys.any, you have no guarantee of how long the wiat will last. Recall that sys.any is basically triggered on every interaction between Specman and the HDL simulator. You probably should be defining a clock event and waiting on that instead, to avoid complex and hard to reproduce bugs in your testbench.

Reply

  • Yes, events are definitely used in TCMs. However it's considered very bad practice to make hierarchical references like your sys.top.phase_monitor.data_valid.This is because you break all the re-use rules, assuming that the phase_monitor will always be located under sys.top an so on. This means your code cannot be reused without modification, and also means that if you have to make any hierarchy changes, you will have to go deep into your code to fix everything that breaks.
    You should instead create a local unit pointer to the phase_monitor, and access the event through the pointer. Here's an example:

     1 <'
     2 unit ph_mon_u {
     3   event data_valid;
     4 };
     5
     6 unit top_u {
     7   phase_monitor : ph_mon_u is instance;
     8 };
     9
    10 unit mem_u {
    11   !p_phase_monitor : ph_mon_u ;
    12   demo()@sys.any is {
    13     sync @p_phase_monitor.data_valid;
    14     wait cycle;
    15   };
    16 };
    17
    18 extend sys {
    19   top : top_u is instance;
    20   mem : mem_u is instance;
    21   connect_pointers() is also {
    22     mem.p_phase_monitor = top.phase_monitor;
    23   };
    24 };
    25 '>

     

    Please also note that if you "wait cycle" on sys.any, you have no guarantee of how long the wiat will last. Recall that sys.any is basically triggered on every interaction between Specman and the HDL simulator. You probably should be defining a clock event and waiting on that instead, to avoid complex and hard to reproduce bugs in your testbench.

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