Specman - Error: Cannot access null port expression

Specman - Error: Cannot access null port expression

我有一个具有以下功能的监视器 fields/events: uart_env.e:

unit uart_monitor_u like uvm_monitor{
   smp : uart_signal_map_u; //ptr to smp
   keep smp  == get_enclosing_unit(uart_env_u).smp;
   kind : uart_monitor_u_kind_t; 

};

uart_monitor.e:

extend uart_monitor_u{
   !port_data_b : inout simple_port of bit; -- pointer to the data-bit port
   event clk_e is rise (smp.port_uart_clk$) @sim;
   event data_deassert is fall (port_data_b$) @uart_clk_e;
   .......
   .......
};

uart_rx_monitor.e:

extend RX uart_monitor_u{
   keep soft port_data_b == smp.port_rxdi;
   .....
   .....
};

uart_types.e:

type uart_monitor_u_kind_t: [ RX, TX ];

uart_signal_map.e:

extend uart_signal_map_u {

    p_def port_uart_clk           bit;
    p_def port_uart_clk_period    real;
    p_def port_resetn             bit;

    p_def port_br_clk_period      real;
    p_def port_uart_int           bit;  
    p_def port_txdo               bit;   

    p_def port_rxdi               bit;
    ......
    ...... 
};

相关文件的编译顺序:

import uart_types;
import uart_env;
import uart_monitor;
import uart_rx_monitor;

由于某种原因,我在尝试编译时遇到了以下错误: *** 错误:无法访问空端口表达式。 @uart_monitor 中的第 22 行 事件 data_deassert 是秋天 (port_data_b$) @uart_clk_e;

port_data_b 指针标记为 do-not-generate。所以它仍然是 NULL。 尝试删除“!”来自它