如何使用DPI访问C语言的存储空间

`timescale 1ns/1ps
module testbench;

bit clk;
always #10 clk=~clk;

test _test(clk);

endmodule

program automatic test(input bit clk);

import "DPI" context task _main();
import "DPI" function WriteMem(input int unsigned addr,input int unsigned data);
import "DPI" function int unsigned ReadMem(input int unsigned addr);
export "DPI" task _DMA;

initial
    _main();

task _DMA(input int unsigned Baseaddr,input int Length);
begin
    for(int i=0;i<Length;i++)
    begin
        @(posedge clk);
        //$display("%0d",ReadMem(Baseaddr+4));
        WriteMem(Baseaddr+4*i,ReadMem(Baseaddr+4*i)+1);
    end
end
endtask