By default, SystemVerilog passes arrays by value, copying the entire array.
It is recommended to pass arrays by reference whenever possible for performance reasons.
- If you want your function to modify the array, use
ref
. - If you want your function to read the array, use
const ref
.
Example:
function void pass_by_value(int array[5], int queue[$], int assoc[int]);
// Default.
// A copy of the arrays is made in this function
endfunction
function void pass_by_ref(ref int array[5], ref int queue[$],
ref int assoc[int]);
// Original arrays are being referenced
endfunction
function void pass_by_const_ref(const ref int array[5],
const ref int queue[$],
const ref int assoc[int]);
// Original arrays are being referenced
// And they can be read but cannot be modified in this function
endfunction
Example on EDA Playground: http://www.edaplayground.com/x/2m9