通過任務

Question

駕駛虛擬接口信號的bitslice我試圖創建一個任務是負責設置有點向量的和一個時鐘週期之後將其清除。我的驅動程序代碼下面附：

class my_if_driver extends uvm_driver; 
    `uvm_component_utils(my_if_driver) 

    // Members 
    // UVM stuff 
    virtual my_if_interface vif; 

    function new(string name="my_if_driver", uvm_component parent); 
    super.new(name, parent); 
    endfunction 

    extern function void build_phase(uvm_phase phase); 
    extern function void connect_phase(uvm_phase phase); 
    extern task   run_phase(uvm_phase phase); 

    extern task drive_my_if(my_if_transaction txn); 
    extern task set_then_clear(ref logic signal); 
endclass 

function void my_if_driver::build_phase(uvm_phase phase); 
endfunction 

function void my_if_driver::connect_phase(uvm_phase phase); 
endfunction 

task my_if_driver::run_phase(uvm_phase phase); 
    @(posedge vif.resetn); 
    forever begin 
    seq_item_port.get_next_item(req); 
    fork 
     drive_my_if(req); 
    join_none 
    seq_item_port.item_done(req); 
    end 
endtask 

// NOTE: each 'command-signal' has bit for each tid (transaction ID) 
task my_if_driver::drive_my_if(my_if_transaction txn); 
    // Wait for delay 
    repeat (txn.cycle_delay) @(posedge vif.clk); 
    // Then drive appropriate signal 
    if (txn.my_if_cmd == my_if_transaction::CMDA) begin 
    set_then_clear(vif.my_if_cmd_a[txn.tid]); 
    end 
    else if (txn.my_if_cmd == my_if_transaction::CMDB) begin 
    set_then_clear(vif.my_if_cmd_b[txn.tid]); 
    end 
    else if (txn.my_if_cmd == my_if_transaction::CMDC) begin 
    set_then_clear(vif.my_if_cmd_c[txn.tid]); 
    end 
endtask 

task my_if_driver::set_then_clear(ref logic signal); 
    signal <= 1'b1; 
    @(posedge vif.clk); 
    signal <= 1'b0; 
endtask 

我收到以下錯誤（奎斯塔10.6）：

** Error: path_to_driver.svh(53): LHS in non-blocking assignment may not be an automatic variable

** Error: path_to_driver.svh(55): LHS in non-blocking assignment may not be an automatic variable

這些點到非阻塞賦值在set_then_clear任務「信號」。有沒有辦法通過ref參數指向虛擬接口的位圖？

Answer 1

的LRM說

Because a variable passed by reference may be an automatic variable, a ref argument shall not be used in any context forbidden for automatic variables.

而且你不能按引用傳遞一個位選擇一個擁擠的變量，只有全局變量。

有沒有簡單的方法來做到這一點，而無需編寫單獨的任務，每個CMD，或者選擇您要分配的接口變量的信號任務中一個大case語句。