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X </div></td><td class="Element67" valign="top" width="4%">
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X </div></td><td class="Element67" valign="top" width="21%">
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p_clk </div></td><td class="Element67" valign="top" width="67%">
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p_clk, clk1 and clk2 must be identical </div></td></tr><tr>
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p_clk </div></td><td class="Element67" valign="top" width="67%">
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p_clk and clk2 must be identical </div></td></tr><tr>
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unlocked or multi-clock </div></td><td class="Element67" valign="top" width="67%">
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clk1 and clk2 must be identical. If clk1 and clk2 are different for the case of operator |=>, then it is considered a multi-clock implication </div></td></tr><tr>
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unlocked </div></td><td class="Element67" valign="top" width="67%">
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<p class="Element10">
Resolution of clock for an assert statement is based on the following assumptions:
<ul class="Element632">
<li class="Element602">assert can appear in an always block, initial block or outside procedural context</li>
<li class="Element602">clock is inferred from an always or initial block</li>
<li class="Element602">default clock can be specified using default clocking block</li>
</ul>Table 17-5 specifies the rules for clock resolution when assert appears in an always or initial block, where i_clk is the inferred clock from an always or initial block, d_clk is the default clock, and p_clk is the property clock. </p>
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</p><p class="Element10" style="text-align: center">
<strong>Table 17-5: Resolution of clock in an always or initial block</strong> </p><div class="Element63">
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i_clk </div></td><td class="Element65" valign="top" width="9%">
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d_clk </div></td><td class="Element65" valign="top" width="8%">
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p_clk </div></td><td class="Element65" valign="top" width="28%">
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Resolved clock </div></td><td class="Element65" valign="top" width="47%">
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Semantic restriction </div></td></tr><tr>
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- </div></td><td class="Element67" valign="top" width="9%">
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- </div></td><td class="Element67" valign="top" width="28%">
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unclocked </div></td><td class="Element67" valign="top" width="47%">
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Error. An assertion must have a clock </div></td></tr><tr>
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X </div></td><td class="Element67" valign="top" width="9%">
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- </div></td><td class="Element67" valign="top" width="8%">
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- </div></td><td class="Element67" valign="top" width="28%">
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i_clk </div></td><td class="Element67" valign="top" width="47%">
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- </div></td></tr><tr>
<td class="Element67" valign="top" width="9%">
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X </div></td><td class="Element67" valign="top" width="8%">
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- </div></td><td class="Element67" valign="top" width="28%">
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d_clk </div></td><td class="Element67" valign="top" width="47%">
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</div></td></tr><tr>
<td class="Element67" valign="top" width="9%">
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- </div></td><td class="Element67" valign="top" width="9%">
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- </div></td><td class="Element67" valign="top" width="8%">
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X </div></td><td class="Element67" valign="top" width="28%">
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p_clk </div></td><td class="Element67" valign="top" width="47%">
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</div></td></tr><tr>
<td class="Element67" valign="top" width="9%">
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X </div></td><td class="Element67" valign="top" width="9%">
<div class="Element68">
- </div></td><td class="Element67" valign="top" width="8%">
<div class="Element68">
X </div></td><td class="Element67" valign="top" width="28%">
<div class="Element68">
i_clk </div></td><td class="Element67" valign="top" width="47%">
<div class="Element68">
i_clk and p_clk must be identical </div></td></tr><tr>
<td class="Element67" valign="top" width="9%">
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X </div></td><td class="Element67" valign="top" width="9%">
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X </div></td><td class="Element67" valign="top" width="8%">
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- </div></td><td class="Element67" valign="top" width="28%">
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i_clk </div></td><td class="Element67" valign="top" width="47%">
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- </div></td></tr><tr>
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- </div></td><td class="Element67" valign="top" width="9%">
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X </div></td><td class="Element67" valign="top" width="8%">
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X </div></td><td class="Element67" valign="top" width="28%">
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p_clk </div></td><td class="Element67" valign="top" width="47%">
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- </div></td><td class="Element67" valign="top" width="9%">
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X </div></td><td class="Element67" valign="top" width="28%">
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p_clk </div></td><td class="Element67" valign="top" width="47%">
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- </div></td></tr></table></div></div>
<p class="Element10">
When the assert statement is outside any procedural block, there is no inferred clock. The rules for clock resolution are specified in Table 17-6. </p><p class="Element10" style="text-align: center">
<strong>Table 17-6: Resolution of clock outside a procedural block</strong></p><div class="Element63">
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d_clk </div></td><td class="Element65" valign="top" width="9%">
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p_clk </div></td><td class="Element65" valign="top" width="32%">
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Resolved clock </div></td><td class="Element65" valign="top" width="50%">
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Semantic restriction </div></td></tr><tr>
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- </div></td><td class="Element67" valign="top" width="9%">
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unlocked </div></td><td class="Element67" valign="top" width="50%">
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Error. An assertion must have a clock </div></td></tr><tr>
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X </div></td><td class="Element67" valign="top" width="9%">
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- </div></td><td class="Element67" valign="top" width="32%">
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d_clk </div></td><td class="Element67" valign="top" width="50%">
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X </div></td><td class="Element67" valign="top" width="32%">
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p_clk </div></td><td class="Element67" valign="top" width="50%">
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X </div></td><td class="Element67" valign="top" width="9%">
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X </div></td><td class="Element67" valign="top" width="32%">
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p_clk </div></td><td class="Element67" valign="top" width="50%">
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</div></td></tr></table></div></div>
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<a href="00868.html" target="topic">第十七章 断言</a></p></div>
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<a href="00164.html" target="topic">17.14.1 在多时钟控制特性中的时钟解析</a> </div></td><td class="Element206" valign="top" width="50%">
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Throughout this subsection, s, s1, s2 denote sequences without clocking events; p, p1, p2 denote properties without clocking events; m, m1, m2 denote multiply-clocked sequences, q, q1, q2 denote multiply-clocked properties; and c, c1, c2 denote non-identical clocking event expressions.<br><br>Due to clock flow, juxtaposition of two clocks nullifies the first. This and the nesting of clocking events within other property building operators mean that there are subtleties in the general interpretation of the restrictions about where the clock can change in multiply-clocked properties. For example, </div></td></tr></table></div></div>
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