The difference between function and task in SystemVerilog

1. function

• The default data type is logic Input ;
• It can be passed as a formal parameter ;* function You can return or not return the result , You need keywords when returning return, Do not return. Use void function();
• Only data variables can be declared as... In the formal parameter list ref type , The network type cannot be declared ref;
• function Cannot call task（v Specified in the ）,sv In particular fork…join_none Call in task;
• function If the parameter in the parameter list is not marked with direction , The default is input signal input;

2. task

• You can specify input output inout ref（ reference parameter );
• You can return a value or not （void）, But through output、inout or ref To specify the return value , Out of commission return return ;
• The default type is logic Input ;
• characteristic ：
  • task Unable to get return Return results , Output only （output inout） perhaps ref To return .
  • task Time consuming statements can be placed in , and function no way . Common time-consuming statements @event 、wait event 、 #delay

explain ：

To be called function, Then use function task All possible ;
To be called task, Only use task call .