User guide

3-14
Compiling and Elaborating Your Design
Note:
The -parameters and -pvalue options do not work with a
localparam or a specparam.
Checking for X and Z Values in Conditional Expressions
The -xzcheck compile-time option tells VCS to display a warning
message when it evaluates a conditional expression and finds it to
have an X or Z value.
A conditional expression is of the following types or statements:
• A conditional or if statement:
if(conditional_exp)
$display("conditional_exp is true");
•A case statement:
case(conditional_exp)
1’b1: sig2=1;
1’b0: sig3=1;
1’bx: sig4=1;
1’bz: sig5=1;
endcase
• A statement using the conditional operator:
reg1 = conditional_exp ? 1’b1 : 1’b0;
The following is an example of the warning message that VCS
displays when it evaluates the conditional expression and finds it to
have an X or Z value:
warning ’signal_name’ within scope hier_name in file_name.v:
line_number to x/z at time simulation_time