how to interpret stated verilog parameter definition

[neetin1984]

hi

I was going through a verilog rtl and it have parameter definition in following ways

parameter [NUM_CLK_DOMAIN-1:0] VALID_CLK_DOMAIN = {NUM_CLK_DOMAIN{1'b1}};

localparam [NUM_CLK_DOMAIN_EXPANDED-1:0] VALID_CLK_DOMAIN_EXPANDED = {8{VALID_CLK_DOMAIN}};


someone let me know how to interpret above.

 

[vardan]

Hi,
[NUM_CLK_DOMAIN-1:0] this is range definition.
Previously defined parameter NUM_CLK_DOMAIN equals to width of VALID_CLK_DOMAIN parameter. If range is not defined, it would be 32 bits.
{NUM_CLK_DOMAIN{1'b1}} here replication of concatenation is used.
Let's say NUM_CLK_DOMAIN is 8, then VALID_CLK_DOMAIN parameter will be 8 bits wide, and will get value 8'b1111_1111.

localparam are parameters that cannot be overriden at instantiation or by defparam.