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📁 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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<a href="00860.html" target="topic">第七章 操作符与表达式</a></div>
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<a href="#" onmousedown="showPopup(this, 'popup00140');"><img src="seealsolink.png" border="0" alt="" title=""></a> SystemVerilog 3.1a语言参考手册</div>
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7.20 集合成员资格</div>
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SystemVerilog支持单一值集合以及集合成员资格操作符。&nbsp;</p>
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集合成员资格操作符的语法如下： </p><div class="Element170">
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<div class="Element13"><div class="Element12" id="code00254"><pre class="Element12">inside_expression ::= expression <strong><span style="color: #FF0000">inside {</span></strong>open_range_list<strong><span style="color: #FF0000">}</span></strong> <span style="color: #008000">// 引用自附录A.8.3</span></pre></div></div>
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<strong>语法7-7 — inside表达式语法（摘录自附录A）</strong></p><p class="Element10">
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<span style="color: #0000FF">inside</span>操作符左侧的表达式是任意单一表达式。<span style="color: #0000FF">inside</span>操作符右侧的集合成员资格<i>open_range_list</i>是逗号分割的表达式或范围列表。如果列表中的表达式是一个集合数组，那么它的元素会被遍历，沿着数组深入直到到达一个单一值。集合的成员会被扫描直到找到一个匹配并返回<span style="color: #FF0000">1</span><span style="color: #800080">'</span><span style="color: #0000FF">b</span><span style="color: #FF0000">1</span>。值可以是重复的，所以值与值的范围可以重叠。表达式和范围的计算顺序是不确定的。 </p><div class="Element170">
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<div class="Element13"><div class="Element12" id="code00255"><pre class="Element12"><span style="color: #0000FF">int</span> a<span style="color: #800080">,</span> b<span style="color: #800080">,</span> c<span style="color: #800080">;</span>

<span style="color: #0000FF">if</span> <span style="color: #800080">(</span>a <span style="color: #0000FF">inside</span> <span style="color: #800080">{</span>b<span style="color: #800080">,</span> c<span style="color: #800080">})</span> ...

<span style="color: #0000FF">int</span> array<span style="color: #800080">[</span><span style="color: #FF0000">$</span><span style="color: #800080">] = {</span>3<span style="color: #800080">,</span>4<span style="color: #800080">,</span>5<span style="color: #800080">};</span>
<span style="color: #0000FF">if</span> <span style="color: #800080">(</span>ex <span style="color: #0000FF">inside</span> <span style="color: #800080">{</span>1<span style="color: #800080">,</span> 2<span style="color: #800080">,</span> array<span style="color: #800080">})</span> ... <span style="color: #008000">// 与{1, 2, 3, 4, 5}相同</span></pre></div></div>
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对于非integral类型的表达式，<span style="color: #0000FF">inside</span>操作符使用相等操作符（<span style="color: #800080">==</span>）来执行比较。如果没有找到匹配的值，inside操作符返回<span style="color: #FF0000">1</span><span style="color: #800080">'</span><span style="color: #0000FF">b</span><span style="color: #FF0000">0</span>。integral表达式也使用相等操作符，除了集合中各个值中的<span style="color: #FF0000">z</span>会被当作是不予考虑的位，并且不会考虑这个位的位置。注意：与<span style="color: #0000FF">casez</span>语句所执行的比较不同，位于左侧的表达式中的<span style="color: #FF0000">z</span>值会被考虑在内；不予考虑是单向的。 </p><div class="Element170">
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<div class="Element13"><div class="Element12" id="code00256"><pre class="Element12"><span style="color: #0000FF">logic</span> <span style="color: #800080">[</span><span style="color: #FF0000">2</span><span style="color: #800080">:</span><span style="color: #FF0000">0</span><span style="color: #800080">]</span> val<span style="color: #800080">;</span>
<span style="color: #0000FF">while</span> <span style="color: #800080">(</span>val <span style="color: #0000FF">inside</span> <span style="color: #800080">{</span><span style="color: #FF0000">3</span><span style="color: #800080">'</span><span style="color: #0000FF">b</span><span style="color: #FF0000">1?1</span><span style="color: #800080">})</span> ... <span style="color: #008000">// 匹配于3'b101, 3'b111, 3'b1x1, 3'b1z1</span></pre></div></div>
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如果没有找到匹配，但某些比较结果是<span style="color: #FF0000">x</span>，那么<span style="color: #0000FF">inside</span>操作符应该返回<span style="color: #FF0000">1</span><span style="color: #800080">'</span><span style="color: #0000FF">b</span><span style="color: #FF0000">x</span>。返回值实际是集合中所有与左侧表达式比较结果的或缩减。 </p><div class="Element170">
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<div class="Element13"><div class="Element12" id="code00257"><pre class="Element12"><span style="color: #0000FF">wire</span> r<span style="color: #800080">;</span>
<span style="color: #0000FF">assign</span> r <span style="color: #800080">=</span> <span style="color: #FF0000">3</span><span style="color: #800080">'</span><span style="color: #0000FF">b</span><span style="color: #FF0000">z11</span> <span style="color: #0000FF">inside</span> <span style="color: #800080">{</span><span style="color: #FF0000">3</span><span style="color: #800080">'</span><span style="color: #0000FF">b</span><span style="color: #FF0000">1?1</span><span style="color: #800080">,</span> <span style="color: #FF0000">3</span><span style="color: #800080">'</span><span style="color: #0000FF">b</span><span style="color: #FF0000">011</span><span style="color: #800080">};</span> <span style="color: #008000">// r = 1'bx</span></pre></div></div>
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SystemVerilog可以使用方括号（<span style="color: #800080">[]</span>）来指定一个范围，方括号中包含了一个低边界和高边界，这两个边界值之间用冒号（<span style="color: #800080">:</span>）隔开，例如<span style="color: #800080">[<i></span>low_bound<span style="color: #800080"></i>:<i></span>high_bound<span style="color: #800080"></i>]</span>这样的形式。使用<span style="color: #FF0000">$</span>指定的范围应代表左侧表达式类型的最高或最低值。如果左侧的表达式包含在范围之内，那么会找到一个匹配。当指定了一个范围的时候，表达式必须是定义了关系操作符（<span style="color: #800080">&lt;=</span>，<span style="color: #800080">&gt;=</span>）的单一值。如果冒号左侧的边界大于冒号右侧的边界，那么这个范围是空的并且不包含任何值。&nbsp;</p>
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例如： </p><div class="Element170">
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<div class="Element13"><div class="Element12" id="code00258"><pre class="Element12"><span style="color: #0000FF">bit</span> ba <span style="color: #800080">=</span> a <span style="color: #0000FF">inside</span> <span style="color: #800080">{[</span><span style="color: #FF0000">16</span><span style="color: #800080">:</span><span style="color: #FF0000">23</span><span style="color: #800080">], [</span><span style="color: #FF0000">32</span><span style="color: #800080">:</span><span style="color: #FF0000">47</span><span style="color: #800080">]};</span>

<span style="color: #0000FF">string</span> I<span style="color: #800080">;</span>
<span style="color: #0000FF">if</span> <span style="color: #800080">(</span>I <span style="color: #0000FF">inside</span> <span style="color: #800080">{[</span><span style="color: #575D94">&quot;a rock&quot;</span><span style="color: #800080">:</span><span style="color: #575D94">&quot;hard place&quot;</span><span style="color: #800080">]})</span> ...
    <span style="color: #008000">// I在&quot;a rock&quot;和&quot;hard place&quot;之间</span></pre></div></div>
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