📄 00295.html
字号:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN">
<html>
<head>
<title>26.3 过程赋值与解赋值语句</title>
<meta http-equiv="Content-Type" content="text/html; charset=GB2312" />
<meta name="generator" content="Doc-O-Matic" />
<meta http-equiv="Content-Style-Type" content="text/css" />
<link rel="STYLESHEET" href="default.css" type="text/css" />
<script type="text/javascript" src="scripts.js"></script>
</head>
<body class="Element700" onload="onBodyLoadEx('systemverilog31a.html', 'topic', '00295.html');" onmousedown="onBodyMouseDown();">
<!-- Begin Popups -->
<div class="Element801" id="popup00478">
<div class="Element800">
<div class="Element14">
链接</div>
<div class="Element11">
<div class="Element10">
<a href="00850.html" target="topic">第二十六章 考虑从SystemVerilog中删除的功能</a></div>
</div>
</div>
</div>
<!-- End Popups -->
<!-- Begin Page Header -->
<div class="Element710" id="areafixed">
<div class="Element92">
<table width="100%" cellspacing="0" cellpadding="0">
<tr><td width="33%">
<div class="Element1">
<a href="#" onmousedown="showPopup(this, 'popup00478');"><img src="seealsolink.png" border="0" alt="" title=""></a> SystemVerilog 3.1a语言参考手册</div>
</td><td width="34%">
<div class="Element2">
</div>
</td><td width="33%">
<div class="Element90">
<a href="00294.html" target="topic"><img src="btn_prev_lightblue.gif" border="0" alt="Previous" title="Previous" onmouseover="switchImage(this, 'btn_prev_lightblue_hover.gif');" onmouseout="switchImage(this, 'btn_prev_lightblue.gif');"></a><a href="00850.html" target="topic"><img src="btn_up_lightblue.gif" border="0" alt="Up" title="Up" onmouseover="switchImage(this, 'btn_up_lightblue_hover.gif');" onmouseout="switchImage(this, 'btn_up_lightblue.gif');"></a><a href="00851.html" target="topic"><img src="btn_next_lightblue.gif" border="0" alt="Next" title="Next" onmouseover="switchImage(this, 'btn_next_lightblue_hover.gif');" onmouseout="switchImage(this, 'btn_next_lightblue.gif');"></a></div>
</td></tr></table><div class="Element5">
26.3 过程赋值与解赋值语句</div>
</div>
</div>
<!-- End Page Header -->
<!-- Begin Client Area -->
<div class="Element720" id="areascroll">
<div class="Element721">
<!-- Begin Page Content -->
<div class="Element58">
<a name="描述"></a><div class="Element11">
<div class="Element10">
<p class="Element10">
The SystemVerilog committee has determined, based on the solicitation of input from tool implementers and tools users, that the procedural assign and deassign statements can be a source of design errors, and can be an impediment to tool implementation. The procedural assign/deassign statements do not provide a capability that cannot be done by another method, which avoids these problems. Therefore, the committee has placed the procedural assign/deassign statements on a deprecation list. This means that a future revision of the Verilog standard might not require support for theses statements. This current standard still requires tools to support the procedural assign/deassign statements. However, users are strongly encouraged to migrate their code to use one of the alternate methods of procedural or continuous assignments. </p>
<p class="Element10">
</p>
<p class="Element10">
Verilog has two forms of the assign statement:
<ul class="Element639">
<li class="Element609">Continuous assignments, placed outside of any procedures</li>
<li class="Element609">Procedural continuous assignments, placed within a procedure</li>
</ul>Continuous assignment statements are a separate process that are active throughout simulation. The continuous assignment statement accurately represents combinational logic at an RTL level of modeling, and is frequently used. </p>
<p class="Element10">
</p>
<p class="Element10">
Procedural continuous assignment statements become active when the assign statement is executed in the procedure. The process can be de-activated using a deassign statement. The procedural assign/deassign statements are seldom needed to model hardware behavior. In the unusual circumstances where the behavior of procedural continuous assignments are required, the same behavior can be modeled using the procedural force and release statements. </p>
<p class="Element10">
</p>
<p class="Element10">
The fact that the assign statement to be used both outside and inside a procedure can cause confusion and errors in Verilog models. The practice of using the assign and deassign statements inside of procedural blocks is highly discouraged.</p></div>
</div>
<a name="Group"></a><div class="Element14">
<a onclick="toggleVisibilityStored('Group');" class="a_Element14"><img src="sectionminus.png" border="0" alt="" title="" id="imgGroup">Group</a></div>
<div id="divGroup">
<div class="Element11">
<div class="Element10">
<p class="Element10">
<a href="00850.html" target="topic">第二十六章 考虑从SystemVerilog中删除的功能</a></p></div>
</div>
</div>
<a name="Links"></a><div class="Element14">
<a onclick="toggleVisibilityStored('链接');" class="a_Element14"><img src="sectionminus.png" border="0" alt="" title="" id="img链接">链接</a></div>
<div id="div链接">
<div class="Element11">
<div class="Element10">
<a href="00850.html" target="topic">第二十六章 考虑从SystemVerilog中删除的功能</a></div>
</div>
</div>
</div>
<!-- End Page Content -->
<!-- Begin Page Footer -->
<hr width="98%" align="center" size="1" color="#CCCCCC" />
<table align="center" cellpadding="0" cellspacing="0" border="0">
<tbody>
<tr height="10">
<td></td>
</tr>
<tr align="center">
<td>
<script type="text/javascript"><!--
google_ad_client = "pub-5266859600380184";
google_ad_width = 468;
google_ad_height = 60;
google_ad_format = "468x60_as";
google_ad_type = "text_image";
google_ad_channel ="";
google_page_url = document.location;
//--></script>
<script type="text/javascript"
src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
</script>
</td>
</tr>
<tr height="15">
<td></td>
</tr>
<tr align="center">
<td>
<font size=2>除非特别声明，原文版权归作者所有，如有转摘请注明原作者以及译者（<a href="http://www.fpgatech.net/" target="_blank">FPGA技术网</a>）信息。<br />
如果您对本主题有何建议或意见，请登陆<a href="http://www.fpgatech.net/forum/forumdisplay.php?fid=18" target="_blank">FPGA开发者家园</a>提交，您的参与是我们前进的动力。</font>
<script language="javascript" type="text/javascript" src="http://js.users.51.la/195685.js"></script>
<noscript><a href="http://www.51.la/?195685" target="_blank"><img alt="我要啦免费统计" src="http://img.users.51.la/195685.asp" style="border:none" /></a></noscript>
</td>
</tr>
</tbody>
</table>
<!-- End Page Footer -->
</div>
</div>
<!-- End Client Area -->
</body></html>⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -