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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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The coverage group cov3 crosses variable b_var with coverage point A (labeled CC). Variable b_var automatically creates 16 bins (auto[0]...auto[15]). Coverage point A explicitly creates 10 bins yy[0]...yy[9]. The cross of two coverage points creates 16 * 10 = 160 cross product bins, namely the pairs shown below: </p><div class="Element170">
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<div class="Element13"><div class="Element12" id="code00901"><pre class="Element12">&lt;auto[0], yy[0]&gt;
&lt;auto[0], yy[1]&gt;
...
&lt;auto[0], yy[9]&gt;
&lt;auto[1], yy[0]&gt;
...
&lt;auto[15], yy[9]&gt;</pre></div></div>
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Cross coverage is allowed only between coverage points defined within the same coverage group. Coverage points defined in a coverage group other than the one enclosing the cross cannot participate in a cross. Attempts to cross items from different coverage groups shall result in a compiler error.&nbsp;</p>
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In addition to specifying the coverage points that are crossed, SystemVerilog includes a powerful set of operators that allow defining cross coverage bins. Cross coverage bins can be specified in order to group together a set of cross products. A cross-coverage bin associates a name and a count with a set of cross products. The count of the bin is incremented every time any of the cross products match, i.e., every coverage point in the cross matches its corresponding bin in the cross product.&nbsp;</p>
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User-defined bins for cross coverage are defined using bins select-expressions. The syntax for defining these bin selection expressions is given in Syntax 20-4.&nbsp;</p>
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The binsof construct yields the bins of its expression, which can be either a coverage point (explicitly defined or implicitly defined for a single variable) or a coverage-point bin. The resulting bins can be further selected by including (or excluding) only the bins whose associated values intersect a desired set of values. The desired set of values can be specified using a comma-separated list of open_value_range as shown in Syntax 20-4. For example, the following select expression: </p><div class="Element170">
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<div class="Element13"><div class="Element12" id="code00902"><pre class="Element12">binsof( x ) intersect { y }</pre></div></div>
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denotes the bins of coverage point x whose values intersect the range given by y. Its negated form: </p><div class="Element170">
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<div class="Element13"><div class="Element12" id="code00903"><pre class="Element12">! binsof( x ) intersect { y }</pre></div></div>
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denotes the bins of coverage point x whose values do not intersect the range given by y.&nbsp;</p>
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The open_value_range syntax can specify a single value, a range of values, or an open range, which denotes the following: </p><div class="Element170">
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<div class="Element13"><div class="Element12" id="code00904"><pre class="Element12">[ $ : value ] =&gt; The set of values less than or equal to value
[ value : $ ] =&gt; The set of values greater or equal to value</pre></div></div>
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The bins selected can be combined with other selected bins using the logical operators &amp;&amp; and || .</p></div>
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<a href="00856.html" target="topic">第二十章 覆盖</a></p></div>
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主题&nbsp;</div></td><td class="Element204" valign="top" width="50%">
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描述&nbsp;</div></td></tr><tr>
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<a href="00254.html" target="topic">20.5.1 Example of user-defined cross coverage and select expressions</a>&nbsp;</div></td><td class="Element206" valign="top" width="50%">
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<a href="00255.html" target="topic">20.5.2 Excluding cross products</a>&nbsp;</div></td><td class="Element206" valign="top" width="50%">
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A group of bins can be excluded from coverage by specifying a select expression using ignore_bins. For example: &nbsp;</div></td></tr><tr>
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<a href="00256.html" target="topic">20.5.3 Specifying Illegal cross products</a>&nbsp;</div></td><td class="Element206" valign="top" width="50%">
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A group of bins can be marked as illegal by specifying a select expression using illegal_bins. For example: &nbsp;</div></td></tr></table></div></div>
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<a href="00856.html" target="topic">第二十章 覆盖</a>, <a href="00964.html" target="topic">主题</a></div>
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