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<div class="CSection"><div class=CTopic id=MainTopic><h1 class=CTitle><a name="OVM_Class_Reference" href="../../ovm_ref/intro.txt">OVM Class Reference</a></h1><div class=CBody><p>The OVM Class Library provides the building blocks needed to quickly develop well-constructed and reusable verification components and test environments in SystemVerilog.</p><p>This OVM Class Reference Guide provides detailed reference information for each user-visible class in the OVM library.&nbsp; For additional information on using OVM, see the OVM User Guide located in the top level directory within the OVM kit.</p><p>We divide the OVM classes and utilities into categories pertaining to their role or function.&nbsp; A more detailed overview of each category-- and the classes comprising them-- can be found in the menu at left.</p><table border=0 cellspacing=0 cellpadding=0 class=CDescriptionList><tr><td class=CDLEntry>Base</td><td class=CDLDescription>This basic building blocks for all environments are components, which do the actual work, transactions, which convey information between components, and ports, which provide the interfaces used to convey transactions.&nbsp;  The OVM&rsquo;s core <i>base</i> classes provide these building blocks.&nbsp; See <a href="base-txt.html#Core_Base_Classes" class=LSection id=link1 onMouseOver="ShowTip(event, 'tt1', 'link1')" onMouseOut="HideTip('tt1')">Core Base Classes</a> for more information.</td></tr><tr><td class=CDLEntry>Reporting</td><td class=CDLDescription>The <i>reporting</i> classes provide a facility for issuing reports (messages) with consistent formatting and configurable side effects, such as logging to a file or exiting simulation.&nbsp;  Users can also filter out reports based on their verbosity , unique ID, or severity.&nbsp; See <a href="reporting-txt.html#Reporting_Classes" class=LGroup id=link2 onMouseOver="ShowTip(event, 'tt2', 'link2')" onMouseOut="HideTip('tt2')">Reporting Classes</a> for more information.</td></tr><tr><td class=CDLEntry>Factory</td><td class=CDLDescription>As the name implies, the OVM factory is used to manufacture (create) OVM objects and components.&nbsp;  Users can configure the factory to produce an object of a given type on a global or instance basis.&nbsp; Use of the factory allows dynamically configurable component hierarchies and object substitutions without having to modify their code and without breaking encapsulation.&nbsp; See <a href="factory-txt.html#Factory_Classes" class=LSection id=link3 onMouseOver="ShowTip(event, 'tt3', 'link3')" onMouseOut="HideTip('tt3')">Factory Classes</a> for details.</td></tr><tr><td class=CDLEntry>Sychronization</td><td class=CDLDescription>The OVM provides event and barrier synchronization classes for process synchronization.&nbsp; See <a href="synchro-txt.html#Synchronization_Classes" class=LSection >Synchronization Classes</a> for more information.</td></tr><tr><td class=CDLEntry>Policies</td><td class=CDLDescription>Each of OVM&rsquo;s policy classes perform a specific task for ovm_object-based objects: printing, comparing, recording, packing, and unpacking.&nbsp; They are implemented separately from ovm_object so that users can plug in different ways to print, compare, etc. without modifying the object class being operated on.&nbsp; The user can simply apply a different printer or compare &ldquo;policy&rdquo; to change how an object is printed or compared.&nbsp;  See <a href="../files/methodology/ovm_policies-svh.html#Policy_Classes" class=LGroup id=link4 onMouseOver="ShowTip(event, 'tt4', 'link4')" onMouseOut="HideTip('tt4')">Policy Classes</a> for more information.</td></tr><tr><td class=CDLEntry>TLM</td><td class=CDLDescription>The OVM TLM library defines several abstract, transaction-level interfaces and the ports and exports that facilitate their use.&nbsp;  Each TLM interface consists of one or more methods used to transport data, typically whole transactions (objects) at a time.&nbsp;  Component designs that use TLM ports and exports to communicate are inherently more reusable, interoperable, and modular.&nbsp; See <a href="tlm_ifs_and_ports-txt.html#TLM_Interfaces,Ports,and_Exports" class=LSection id=link5 onMouseOver="ShowTip(event, 'tt5', 'link5')" onMouseOut="HideTip('tt5')">TLM Interfaces, Ports, and Exports</a> for details.</td></tr><tr><td class=CDLEntry>Components</td><td class=CDLDescription>Components form the foundation of the OVM.&nbsp; They encapsulate behavior of drivers, scoreboards, and other objects in a testbench.&nbsp; The OVM library provides a set of predefined component types, all derived directly or indirectly from <a href="../files/base/ovm_component-svh.html#ovm_component" class=LClass id=link6 onMouseOver="ShowTip(event, 'tt6', 'link6')" onMouseOut="HideTip('tt6')">ovm_component</a>.&nbsp;  See <a href="components-txt.html#Predefined_Component_Classes" class=LGroup id=link7 onMouseOver="ShowTip(event, 'tt7', 'link7')" onMouseOut="HideTip('tt7')">Predefined Component Classes</a> for more information.</td></tr><tr><td class=CDLEntry>Sequencers</td><td class=CDLDescription>The sequencer serves as an arbiter for controlling transaction flow from multiple stimulus generators.&nbsp; More specifically, the sequencer controls the flow of <a href="../files/methodology/sequences/ovm_sequence_item-svh.html#ovm_sequence_item" class=LClass id=link8 onMouseOver="ShowTip(event, 'tt8', 'link8')" onMouseOut="HideTip('tt8')">ovm_sequence_item</a>-based transactions generated by one or more <a href="../files/methodology/sequences/ovm_sequence-svh.html#ovm_sequence#(REQ,RSP)" class=LClass id=link9 onMouseOver="ShowTip(event, 'tt9', 'link9')" onMouseOut="HideTip('tt9')">ovm_sequence #(REQ,RSP)</a>-based sequences.&nbsp; See <a href="sequencers-txt.html#Sequencer_Classes" class=LSection id=link10 onMouseOver="ShowTip(event, 'tt10', 'link10')" onMouseOut="HideTip('tt10')">Sequencer Classes</a> for more information.</td></tr><tr><td class=CDLEntry>Sequences</td><td class=CDLDescription>Sequences encapsulate user-defined procedures that generate multiple <a href="../files/methodology/sequences/ovm_sequence_item-svh.html#ovm_sequence_item" class=LClass id=link11 onMouseOver="ShowTip(event, 'tt8', 'link11')" onMouseOut="HideTip('tt8')">ovm_sequence_item</a>-based transactions.&nbsp; Such sequences can be reused, extended, randomized, and combined sequentially and hierarchically in interesting ways to produce realistic stimulus to your DUT.&nbsp; See <a href="sequences-txt.html#Sequence_Classes" class=LSection id=link12 onMouseOver="ShowTip(event, 'tt11', 'link12')" onMouseOut="HideTip('tt11')">Sequence Classes</a> for more information.</td></tr><tr><td class=CDLEntry>Macros</td><td class=CDLDescription>The OVM provides several macros to help increase user productivity.&nbsp; See &lt;Utility and Field Macros&gt; and <a href="../files/macros/ovm_sequence_defines-svh.html#Sequence_and_Do_Action_Macros" class=LSection >Sequence and Do Action Macros</a> for a complete list.</td></tr><tr><td class=CDLEntry>Globals</td><td class=CDLDescription>This category defines a small list of types, variables, functions, and tasks defined in <i>ovm_pkg</i> scope.&nbsp;  These items are accessible from any scope that imports the <i>ovm_pkg</i>.&nbsp; See <a href="../files/base/ovm_object_globals-svh.html#Types_and_Enumerations" class=LSection >Types and Enumerations</a> and <a href="../files/base/ovm_globals-svh.html#Globals" class=LSection >Globals</a> for details.</td></tr></table></div></div></div>

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<div class=CToolTip id="tt1"><div class=CSection>The OVM library defines a set of base classes and utilities that facilitate the design of modular, scalable, reusable verification environments.</div></div><div class=CToolTip id="tt2"><div class=CGroup>The reporting classes provide a facility for issuing reports with consistent formatting. </div></div><div class=CToolTip id="tt3"><div class=CSection>As the name implies, the ovm_factory is used to manufacture (create) OVM objects and components. </div></div><div class=CToolTip id="tt4"><div class=CGroup>Policy classes are used to implement polymorphic operations that differ between built-in types and class-based types. </div></div><div class=CToolTip id="tt5"><div class=CSection>The OVM TLM library defines several abstract, transaction-level interfaces and the ports and exports that facilitate their use. </div></div><div class=CToolTip id="tt6"><div class=CClass><blockquote><table border=0 cellspacing=0 cellpadding=0 class=Prototype><tr><td>virtual class ovm_component extends ovm_report_object</td></tr></table></blockquote>The ovm_component class is the root base class for OVM components. </div></div><div class=CToolTip id="tt7"><div class=CGroup>Components form the foundation of the OVM. </div></div><div class=CToolTip id="tt8"><div class=CClass><blockquote><table border=0 cellspacing=0 cellpadding=0 class=Prototype><tr><td>class ovm_sequence_item extends ovm_transaction</td></tr></table></blockquote>The base class for user-defined sequence items and also the base class for the ovm_sequence class. </div></div><div class=CToolTip id="tt9"><div class=CClass><blockquote><table border=0 cellspacing=0 cellpadding=0 class=Prototype><tr><td><table border=0 cellspacing=0 cellpadding=0><tr><td class=PBeforeParameters colspan=5>virtual class ovm_sequence #(</td></tr><tr><td>&nbsp;&nbsp;&nbsp;</td><td class=PType nowrap>type&nbsp;</td><td class=PParameter nowrap>REQ</td><td class=PDefaultValuePrefix>&nbsp;=&nbsp;</td><td class=PDefaultValue width=100%> ovm_sequence_item,</td></tr><tr><td>&nbsp;&nbsp;&nbsp;</td><td class=PType nowrap>type&nbsp;</td><td class=PParameter nowrap>RSP</td><td class=PDefaultValuePrefix>&nbsp;=&nbsp;</td><td class=PDefaultValue width=100%> REQ</td></tr><tr><td class=PAfterParameters colspan=5>) extends ovm_sequence_base</td></tr></table></td></tr></table></blockquote>The ovm_sequence class provides the interfaces necessary in order to create streams of sequence items and/or other sequences.</div></div><div class=CToolTip id="tt10"><div class=CSection>The sequencer serves as an arbiter for controlling transaction flow from multiple stimulus generators. </div></div><div class=CToolTip id="tt11"><div class=CSection>Sequences encapsulate user-defined procedures that generate multiple ovm_sequence_item-based transactions. </div></div><!--END_ND_TOOLTIPS-->

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