00548.html

这是一本关于verilog编程语言的教程,对学习verilog语言有帮助

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<li value="8" class="Element600">应用于在一个包中声明的枚举、非压缩结构体、非压缩联合体或一个类类型的<span style="color: #0000FF">typedef</span>总是等价于其本身，而不管类型导入的范围如何。</li>
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一个类型标识符的作用范围包括层次化的实例范围。这也就意味着内部声明了用户定义类型的每一个实例都产生了一个唯一的类型。为了在相同模块、接口、或程序的多个实例间具有类型等价性，一个类型必须在比模块、接口、或程序声明更高层次的编译单元范围内声明，或者从一个包中导入。&nbsp;</p>
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虽然包声明不需要在相同的编译单元内，然而下面的例子假设它们都处于一个编译单元。 </p><div class="Element170">
<a href="#" onclick="CopyElementToClipboard('code00208');">Copy Code</a></div>
<div class="Element13"><div class="Element12" id="code00208"><pre class="Element12"><span style="color: #0000FF">package</span> p1<span style="color: #800080">;</span>
    <span style="color: #0000FF">typedef struct</span> <span style="color: #800080">{</span>
<span style="color: #0000FF">        int</span> A<span style="color: #800080">;</span>
    <span style="color: #800080">}</span> t_1<span style="color: #800080">;</span>
<span style="color: #0000FF">endpackage</span>

<span style="color: #0000FF">typedef struct</span> <span style="color: #800080">{</span>
<span style="color: #0000FF">    int</span> A<span style="color: #800080">;</span>
<span style="color: #800080">}</span> t_2<span style="color: #800080">;</span>

<span style="color: #0000FF">module</span> sub<span style="color: #800080">();</span>
<span style="color: #0000FF">    import</span> p1<span style="color: #800080">:</span>t_1<span style="color: #800080">;</span>
<span style="color: #0000FF">    parameter type</span> t_3 <span style="color: #800080">=</span> <span style="color: #0000FF">int</span><span style="color: #800080">;</span>
<span style="color: #0000FF">    parameter type</span> t_4 <span style="color: #800080">=</span> <span style="color: #0000FF">int</span><span style="color: #800080">;</span>
<span style="color: #0000FF">    typedef struct</span> <span style="color: #800080">{</span><span style="color: #0000FF">int</span> A<span style="color: #800080">;}</span> t_5<span style="color: #800080">;</span>
    t_1 v1<span style="color: #800080">;</span> t_2 v2<span style="color: #800080">;</span> t_3 v3<span style="color: #800080">;</span> t_4 v4<span style="color: #800080">;</span> t_5 v5<span style="color: #800080">;</span>
<span style="color: #0000FF">endmodule</span>

<span style="color: #0000FF">module</span> top<span style="color: #800080">();</span>
<span style="color: #0000FF">    typedef struct</span> <span style="color: #800080">{</span><span style="color: #0000FF">int</span> A<span style="color: #800080">;}</span> t_6<span style="color: #800080">;</span>
    sub <span style="color: #800080">#(.</span>t_3<span style="color: #800080">(</span>t_6<span style="color: #800080">))</span> s1<span style="color: #800080">();</span>
    sub <span style="color: #800080">#(.</span>t_3<span style="color: #800080">(</span>t_6<span style="color: #800080">))</span> s2<span style="color: #800080">();</span>

<span style="color: #0000FF">    initial begin</span>
        s1.v1 <span style="color: #800080">=</span> s2<span style="color: #800080">.</span>v1<span style="color: #800080">;</span> <span style="color: #008000">// 合法的 - 两个类型均来自于包p1（规则8）</span>
        s1.v2 <span style="color: #800080">=</span> s2<span style="color: #800080">.</span>v2<span style="color: #800080">;</span> <span style="color: #008000">// 合法的 - 两个类型均来自于$unit（规则4）</span>
        s1.v3 <span style="color: #800080">=</span> s2<span style="color: #800080">.</span>v3<span style="color: #800080">;</span> <span style="color: #008000">// 合法的 - 两个类型均来自于top（规则2）</span>
        s1.v4 <span style="color: #800080">=</span> s2<span style="color: #800080">.</span>v4<span style="color: #800080">;</span> <span style="color: #008000">// 合法的 - 两个类型均为int（规则1）</span>
        s1.v5 <span style="color: #800080">=</span> s2<span style="color: #800080">.</span>v5<span style="color: #800080">;</span> <span style="color: #008000">// 非法的 - 类型来自于s1和s2（规则4）</span>
<span style="color: #0000FF">    end</span>
<span style="color: #0000FF">endmodule</span></pre></div></div>
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