We assume that you understand case (casez, casex) statement as well as if-else statement. So, the focus is on full_case and parallel_case directives.
The synthesis directives are added as a comment immediately after the case expression and before any of the case items as shown below.
case (case_expression) // synopsys full_case parallel_case
case_item1 : statement1;
case_item2 : statement2;
default : statement3;
endcase
