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17.6 声明序列</div>
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一个序列可以在下列单元中声明：
<ul class="Element631">
<li class="Element601">一个模块</li>
<li class="Element601">一个接口</li>
<li class="Element601">一个程序</li>
<li class="Element601">一个时钟控制块</li>
<li class="Element601">一个包</li>
<li class="Element601">一个编译单元的作用范围</li>
</ul>序列使用下列的语法进行声明： </p><div class="Element170">
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<div class="Element13"><div class="Element12" id="code00587"><pre class="Element12">concurrent_assertion_item_declaration ::= <span style="color: #008000">// 引用自附录A.2.10</span>
...
| sequence_declaration
sequence_declaration ::=
<strong><span style="color: #FF0000">sequence</span></strong> sequence_identifier[<strong><span style="color: #FF0000">(</span></strong>[list_of_formals]<strong><span style="color: #FF0000">)</span></strong>]<strong><span style="color: #FF0000">;</span></strong>
{assertion_variable_declaration}
sequence_expr<strong><span style="color: #FF0000">;</span></strong>
<strong><span style="color: #FF0000">endsequence</span></strong> [<strong><span style="color: #FF0000">:</span></strong> sequence_identifier]
sequence_instance ::=
ps_sequence_identifier [<strong><span style="color: #FF0000">(</span></strong>[actual_arg_list]<strong><span style="color: #FF0000">)</span></strong>]
actual_arg_list ::=
actual_arg_expr {<strong><span style="color: #FF0000">,</span></strong> actual_arg_expr}
| <strong><span style="color: #FF0000">.</span></strong>formal_identifier<strong><span style="color: #FF0000">(</span></strong>actual_arg_expr<strong><span style="color: #FF0000">)</span></strong>{<strong><span style="color: #FF0000">, .</span></strong>formal_identifier<strong><span style="color: #FF0000">(</span></strong>actual_arg_expr<strong><span style="color: #FF0000">)</span></strong>}
actual_arg_expr ::=
event_expression
| <strong><span style="color: #FF0000">$</span></strong>
assertion_variable_declaration ::=
data_type list_of_variable_identifiers<strong><span style="color: #FF0000">;</span></strong></pre></div></div>
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<strong>语法17-4 — 序列声明语法（摘录自附录A）</strong></p><p class="Element10">
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<i><span class="Element146">clocking_event</span></i>为序列指定了时钟。 </p>
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一个序列声明可以带有可选的形式参数。当一个序列被实例化的时候，可以将实型参数传递到序列。通过使用实型参数替代形式参数，序列被展开。SystemVerilog会执行语义检查以确保使用真实参数展开的序列是合法的。 </p>
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一个实型参数可以替代一个：
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<li class="Element601">标识符</li>
<li class="Element601">表达式</li>
<li class="Element601">事件控制表达式</li>
<li class="Element601">标记成<span style="color: #FF0000">$</span>的上限范围</li>
</ul>注意，在一个序列中使用，但不是序列形式参数的变量从序列被声明的作用域中根据作用域规则被求解。 </p><div class="Element170">
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<div class="Element13"><div class="Element12" id="code00588"><pre class="Element12"><span style="color: #0000FF">sequence</span> s1<span style="color: #800080">;</span>
<span style="color: #800080">@(</span><span style="color: #0000FF">posedge</span> clk<span style="color: #800080">)</span> a <span style="color: #800080">##</span><span style="color: #FF0000">1</span> b <span style="color: #800080">##</span><span style="color: #FF0000">1</span> c<span style="color: #800080">;</span>
<span style="color: #0000FF">endsequence</span>
<span style="color: #0000FF">sequence</span> s2<span style="color: #800080">;</span>
<span style="color: #800080">@(</span><span style="color: #0000FF">posedge</span> clk<span style="color: #800080">)</span> d <span style="color: #800080">##</span><span style="color: #FF0000">1</span> e <span style="color: #800080">##</span><span style="color: #FF0000">1</span> f<span style="color: #800080">;</span>
<span style="color: #0000FF">endsequence</span>
<span style="color: #0000FF">sequence</span> s3<span style="color: #800080">;</span>
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