ovm mentograf

7/28/2019 Ovm Mentograf

1/24

[email protected]

www.verificationacademy.com

Advanced OVM (& UVM)Understanding the Factory

Tom FitzpatrickVerification Technologist


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Create() vs. New()

Objects must beconstructed

new() hard-codes thetype

create() returns a

constructed instancefrom the factory

The factory lets youchange the type of thecreated component Without modifying the

instantiating code

comp1

comp2

comp2


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Registering with the Factory

Objects are registeredwith the factory

via macro

`ovm_object_utils

ovm_component_utils

comp1

No ;


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via macro

`ovm_object_utils

ovm_component_utils

Macro createstype_id wrapper

Static methodsin wrapper

create(): returns an instance of the type (no $cast needed) get_type(): returns the type handle

comp1

No ;

Desired type

Wrapper


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via macro

`ovm_object_utils

ovm_component_utils

Macro createstype_id wrapper

Static methodsin wrapper

create(): returns an instance of the type (no $cast needed) get_type(): returns the type handle

set_type_override() set_inst_override()

comp1

No ;

Desired type

Wrapper

Factory type overrides


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Overriding a Type


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Overriding a Type

New Desired type

All Instances

Overridden


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Overriding an Instance

New Desired typeInstance Name

Instance Changed


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Using Parameterized Types

Parameterized type


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Using Parameterized Types


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Environments are Components


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Tests are Components, too!

run_test() creates the test from the factory

modul e t op;. . .

i ni t i albegi n: bl k

. . .run_test( ) ;

end

endmodul e: t op

vsim +OVM_TESTNAME=testCommand line:

Register the testwith the factory


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Tests are Components, too!

Always call run_test() with null argument

modul e t op;. . .

i ni t i albegi n: bl k

. . .run_test( ) ;

end

endmodul e: t op

vsim +OVM_TESTNAME=test2Command line:


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Use Factory on Sequence Items

Sequence Items may also be overriddencl ass my_seq extends

ovm_sequence #( my_t r ) ;

t ask body( ) ;my_t r t x;tx = my_tr: : t ype_i d: : create(tx

endt askendcl ass

Register with Factory


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t ask body( ) ;my_t r t x;tx = my_tr: : t ype_i d: : create( t x, , get _f ul l name( ) ) ;

endt ask

endcl ass


Empty parent for objects

Allow factory to find this sequence


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t ask body( ) ;my_t r t x;tx = my_tr: : t ype_i d: : create( t x, , get _f ul l name( ) ) ;st ar t _i t em( tx) ;asser t ( t x. r andomi ze( ) wi t h { cmd == 0; } ) ;f i ni sh_i t em( t x) ;

endt askendcl ass



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Override items by type

cl ass er r _t est ext ends my_t est ;task run();my_tr: : t ype_i d: : set_type_override( err_tr: : get _t ype( ) ) ;

endt ask

endcl ass


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Override items by type or instance

cl ass er r _t est ext ends my_t est ;task run();my_tr: : t ype_i d: : set_inst_override( err_tr: : get _t ype( ) ,

e. agent . sqr . s1. t x) ;

endt ask

endcl ass


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endt ask

endcl ass

Path to sequencer


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endt ask

endcl ass

Path to sequencer

Sequence name


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endt ask

endcl ass

Path to sequencer

Sequence name

Item name


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Instance overrides let you change the typeof item generated by a particular sequence on a sequencer

a specific item name created by a sequence



endt ask

endcl ass

Path to sequencer

Sequence name

Item name


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Summary

Use `ovm_object/component_utilsmacro to register with the factory

Always call ::type_id::create()

Register tests with the factory

Call run_test() with null argument Specify which test via the command line


24/24

[email protected]

www.verificationacademy.com

Advanced OVM (& UVM)Understanding the Factory

Tom FitzpatrickVerification Technologist

ovm mentograf

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