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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, 'popup00131');"><img src="seealsolink.png" border="0" alt="" title=""></a> SystemVerilog 3.1a语言参考手册</div>
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7.12 串联</div>
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与Verilog一样，花括号（<span style="color: #800080">{ }</span>）被用来表示串联。串联被当作一个压缩的位向量来看待。它可以使用在一条赋值语句或一个表达式的左侧。 </p><div class="Element170">
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<div class="Element13"><div class="Element12" id="code00220"><pre class="Element12"><span style="color: #0000FF">logic</span> log1<span style="color: #800080">,</span> log2<span style="color: #800080">,</span> log3<span style="color: #800080">;</span>
<span style="color: #800080">{</span>log1<span style="color: #800080">,</span> log2<span style="color: #800080">,</span> log3<span style="color: #800080">}</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">111</span><span style="color: #800080">;</span>
<span style="color: #800080">{</span>log1<span style="color: #800080">,</span> log2<span style="color: #800080">,</span> log3<span style="color: #800080">}</span> <span style="color: #800080">=</span> <span style="color: #800080">{</span><span style="color: #FF0000">1</span><span style="color: #800080">'</span><span style="color: #0000FF">b</span><span style="color: #FF0000">1</span><span style="color: #800080">,</span> <span style="color: #FF0000">1</span><span style="color: #800080">'</span><span style="color: #0000FF">b</span><span style="color: #FF0000">1</span><span style="color: #800080">,</span> <span style="color: #FF0000">1</span><span style="color: #800080">'</span><span style="color: #0000FF">b</span><span style="color: #FF0000">1</span><span style="color: #800080">};</span> <span style="color: #008000">// 与3'b111具有相同的效果</span></pre></div></div>
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如果一条赋值语句一侧的串联宽度与另外一侧的表达式的宽度不同，那么软件工具可以产生一个警告信息。对于下面的例子，软件工具可以给出尺寸不匹配的警告信息。 </p><div class="Element170">
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<div class="Element13"><div class="Element12" id="code00221"><pre class="Element12"><span style="color: #0000FF">bit</span> <span style="color: #800080">[</span><span style="color: #FF0000">1</span><span style="color: #800080">:</span><span style="color: #FF0000">0</span><span style="color: #800080">]</span> packedbits <span style="color: #800080">=</span> <span style="color: #800080">{</span><span style="color: #FF0000">32</span><span style="color: #800080">'</span><span style="color: #0000FF">b</span><span style="color: #FF0000">1</span><span style="color: #800080">,</span><span style="color: #FF0000">32</span><span style="color: #800080">'</span><span style="color: #0000FF">b</span><span style="color: #FF0000">1</span><span style="color: #800080">};</span> <span style="color: #008000">// 右侧是64位</span>
<span style="color: #0000FF">int</span> i <span style="color: #800080">=</span> <span style="color: #800080">{</span><span style="color: #FF0000">1</span><span style="color: #800080">'</span><span style="color: #0000FF">b</span><span style="color: #FF0000">1</span><span style="color: #800080">,</span> <span style="color: #FF0000">1</span><span style="color: #800080">'</span><span style="color: #0000FF">b</span><span style="color: #FF0000">1</span><span style="color: #800080">};</span>                 <span style="color: #008000">// 右侧是2位</span></pre></div></div>
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参见<a href="00242.html" target="topic">2.7 数组文本</a>和<a href="00243.html" target="topic">2.8 结构体文本</a>节中有关数组和结构体初始化的信息。&nbsp;</p>
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SystemVerilog增强了串联操作，它允许字符串类型变量的串联。一般情况下，如果一个串联操作的任何一个操作数是字符串类型，那么串联就被当作是字符串，并且所有其它自变量都被隐式转换成字符串类型（参见<a href="00396.html" target="topic">3.7 string数据类型</a>中的描述）。字符串串联只能作为表达式使用，不能使用在赋值语句的左侧。 </p><div class="Element170">
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<div class="Element13"><div class="Element12" id="code00222"><pre class="Element12"><span style="color: #0000FF">string</span> hello <span style="color: #800080">=</span> <span style="color: #575D94">&quot;hello&quot;</span><span style="color: #800080">;</span>
<span style="color: #0000FF">string</span> s<span style="color: #800080">;</span>
s <span style="color: #800080">=</span> <span style="color: #800080">{</span>hello<span style="color: #800080">,</span> <span style="color: #575D94">&quot; &quot;</span><span style="color: #800080">,</span> <span style="color: #575D94">&quot;world&quot;</span><span style="color: #800080">};</span>
<span style="color: #0000FF">$display</span>( <span style="color: #575D94">&quot;%s\n&quot;</span>, s )<span style="color: #800080">;</span>     <span style="color: #008000">// 显示成'hello world'</span>

s <span style="color: #800080">=</span> <span style="color: #800080">{</span>s<span style="color: #800080">,</span> <span style="color: #575D94">&quot; and goodbye&quot;</span><span style="color: #800080">};</span>
<span style="color: #0000FF">$display</span><span style="color: #800080">(</span><span style="color: #575D94">&quot;%s\n&quot;</span><span style="color: #800080">,</span> s<span style="color: #800080">);</span>       <span style="color: #008000">// 显示成'hello world and goodbye'</span></pre></div></div>
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复制操作符（也被称为乘串联）中的花括号还可以与字符串类型的变量一起使用。在字符串复制的情况下，可以使用非常量的乘数。 </p><div class="Element170">
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<div class="Element13"><div class="Element12" id="code00223"><pre class="Element12"><span style="color: #0000FF">int</span> n <span style="color: #800080">=</span> <span style="color: #FF0000">3</span><span style="color: #800080">;</span>
<span style="color: #0000FF">string</span> s <span style="color: #800080">=</span> <span style="color: #800080">{</span>n<span style="color: #800080">{</span><span style="color: #575D94">&quot;boo &quot;</span><span style="color: #800080">}};</span>
<span style="color: #0000FF">$display</span><span style="color: #800080">(</span><span style="color: #575D94">&quot;%s\n&quot;</span><span style="color: #800080">,</span> s<span style="color: #800080">);</span>       <span style="color: #008000">// 显示成'boo boo boo '</span></pre></div></div>
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注意：与位串联不同，字符串串联或复制的结果不会被缩减。相反，目的变量（具有字符串类型）会调整尺寸以便容纳结果字符串。</p></div>
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