shallow copy只能復(fù)制類中的對(duì)象句柄，如果我們還想為這個(gè)對(duì)象句柄實(shí)例化，并復(fù)制其中的內(nèi)容呢？

那就是deep copy的概念了。

deep copy是通過(guò)聲明自定義的copy函數(shù)來(lái)實(shí)現(xiàn)的，這個(gè)自定義的復(fù)制函數(shù)會(huì)復(fù)制類中所有對(duì)象實(shí)例中內(nèi)容。

下面的實(shí)例就實(shí)現(xiàn)了一個(gè)deep copy函數(shù)。

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module class_TOP( );
 class PCIChild;
 logic [7:0] burstC;
 function new (logic [7:0] burst);
 burstC = burst;
 endfunction
 endclass : PCIChild
 class PCITop;
 logic [31:0] addrTop;
 logic [31:0] dataTop;
 PCIChild PCIc;
 function new(logic [31:0] addr, logic [31:0] data, logic 
[7:0] burst);
 PCIc = new(burst); //instantiate PCIc
 addrTop = addr;
 dataTop = data;
 endfunction
 function void copy (PCITop p);
 addrTop = p.addrTop;
 dataTop = p.dataTop;
 PCIc.burstC = p.PCIc.burstC;
 endfunction
 function void disp (string instName);
 $display("[%s] addr = %h data = %h burst=%h", instName, addrTop, dataTop, PCIc.burstC);
 endfunction
 endclass : PCITop
 PCITop PCI1, PCI2;
 initial begin;
 PCI1 = new (32'h 0000_00f, 32'h f0f0_f0f0, 8'h12);
 PCI1.disp("PCI1");
 PCI2 = new (1,2,3);
 PCI2.copy(PCI1); //deep copy PCI1 into PCI2
 PCI2.disp("PCI2"); //copied content displayed
 PCI2.addrTop = 32'h1234_5678;
 PCI2.dataTop = 32'h5678_abcd;
 PCI2.PCIc.burstC = 8'h 9a;
 PCI2.disp("PCI2");
 PCI1.disp("PCI1");
 end
 endmodule

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仿真log:

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[PCI1] addr = 000000ff data = f0f0f0f0 burst=12
[PCI2] addr = 000000ff data = f0f0f0f0 burst=12
[PCI2] addr = 12345678 data = 5678abcd burst=9a
[PCI1] addr = 000000ff data = f0f0f0f0 burst=12
 V C S S i m u l a t i o n R e p o r t

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上面的例子中，我們實(shí)現(xiàn)了一個(gè)自定義的“copy”函數(shù)
:

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function void copy (PCITop p);
 addrTop = p.addrTop;
 dataTop = p.dataTop;
 PCIc.burstC = p.PCIc.burstC;
 endfunction

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通過(guò)一個(gè)copy函數(shù)我們不僅會(huì)復(fù)制類中的屬性，還復(fù)制了類中其他對(duì)象句柄指向的內(nèi)容。

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PCI2.copy(PCI1); //deep copy PCI1 into PCI2

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結(jié)果就是PCI1中的對(duì)象PCIc和PCI2中的對(duì)象PCIc，最終指向不同的內(nèi)存空間。

所以當(dāng)我修改PCI2.PCIc.burstC，不會(huì)反映到PCI1.PCIc.burstC。

　審核編輯：湯梓紅